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The difference between seamless pipe and erw pipe

Date : 2022-01-07

1. Different concepts
Seamless steel pipes are perforated from a whole piece of round steel, and the steel pipes without welds on the surface are called seamless steel pipes; ERW is a hot-rolled coil that is formed by a forming machine and uses the skin effect of high-frequency current. The proximity effect causes the edge of the tube blank to be heated and melted, and pressure welding is carried out under the action of the squeeze roller to realize the produced product.

2. Outer diameter tolerance
ERW steel pipe: It is cold formed and the size is determined by reducing the diameter by 0.6%; the process temperature is basically constant at room temperature. Therefore, the outer diameter can be accurately controlled, and the fluctuation range is small, which helps to eliminate the black leather buckle.
Seamless steel pipe: adopts hot-rolling forming process and is shaped at about 8000℃. The raw material composition, cooling conditions and cooling conditions of the steel pipe roll have a great influence on its outer diameter, so it is difficult to accurately control the outer diameter and fluctuate in a large range.

4. Ovality
ERW steel pipe: cold-formed, accurate outer diameter control, small fluctuation range; seamless steel pipe: hot-rolled forming process, the raw material composition of the steel pipe, cooling conditions and the cooling state of the roll have a great influence on its outer diameter, so external It is difficult to control the diameter accurately, and the fluctuation range is relatively large.

5. Appearance
The outer surface defects of the blanks used in seamless steel pipes cannot be eliminated by the hot rolling process. The defects can only be polished after the finished product is completed; the spiral path left after piercing can only be partially eliminated in the process of reducing the wall.
ERW steel pipe uses hot-rolled coils as raw materials. The surface quality of the coils is the surface quality of ERW steel pipes. The surface quality of hot-rolled coils is easy to control and high in quality. Therefore, the surface quality of ERW steel pipes is far better than seamless steel pipes. .

6. Straightness
Seamless steel pipes are formed in a plastic state, and it is relatively difficult to control the straightness of the pipe end with a single ruler (continuous rolling is 3 to 4 times ruler); ERW steel pipes are cold processed and have online straightening in the reduced diameter state. In addition, it is infinite times the ruler, so the straightness is better.

3. Wall thickness tolerance
Seamless steel pipe: It is produced by round steel perforation method, and the wall thickness deviation is large. The subsequent hot rolling can partially eliminate the unevenness of the wall thickness, but the most advanced unit can only be controlled within ±5~10%t; ERW steel pipe :Using hot-rolled coils as raw materials, the thickness tolerance of modern hot-rolling can be controlled within 0.05mm.

7. Tensile test
The tensile properties of the seamless steel pipe and the ERW steel pipe are in line with the API standard, but the strength of the seamless steel pipe is generally at the upper limit and the plasticity is at the lower limit. In comparison, the strength index of the ERW steel pipe is in the best state, and the plasticity index is 33.3% higher than the standard. The reason is that the performance of the hot-rolled coil, the raw material of ERW steel pipe, is guaranteed by means of microalloying smelting, out-of-furnace refining, and controlled cooling and rolling; a reasonable match.

8. Hardness
The raw material of ERW steel pipe, the hot-rolled coil, has extremely high precision of controlled cooling and rolling during the rolling process, which can ensure the uniform performance of each part of the coil.

9. Grain size
The raw material of ERW steel pipe, the hot-rolled coil, is a wide and thick continuous casting billet, with a thick fine-grained surface solidification layer, no columnar crystal region, shrinkage cavity and looseness, small composition deviation and dense structure; in the subsequent rolling process Among them, the application of controlled cooling and controlled rolling technology further ensures the grain size of raw materials.

10. Anti-collapse test
ERW steel pipes are characterized by their raw materials and pipe-making processes. Its wall thickness uniformity and ovality are far superior to those of seamless steel pipes, which are the main reasons why the collapse resistance is higher than that of seamless steel pipes.

11. Impact test
Since the impact toughness of the base material of ERW steel pipe is several times that of seamless steel pipe, the impact toughness of the weld seam is the key of ERW steel pipe. By controlling the impurity content of raw materials, the height and direction of slitting burrs, the shape of the forming edge, the welding angle, and the welding speed , Heating power and frequency, welding extrusion volume, intermediate frequency withdrawal temperature and depth, air-cooling section length and other process parameters ensure that the impact energy of the weld reaches more than 60% of the base material. If further optimized, the weld impact energy can be close to the base material. Material to achieve seamless performance.

12. Blasting test
The blasting test performance of ERW steel pipe is much higher than the standard requirement, mainly due to the high uniformity of wall thickness and uniform outer diameter of ERW steel pipe.

13.Consumption of steel for 10,000-meter footage casing
The wall thickness of ERW steel pipe is uniform, and its wall thickness tolerance can be neglected. The control accuracy limit of seamless steel pipe wall thickness difference is ±5%t, and it is generally controlled at ±5-10%t. In order to ensure that the minimum wall thickness can meet the standard requirements and performance, the solution can only be solved by appropriately increasing the wall thickness. Therefore, in the casing of the same specification and the same weight, the ERW steel pipe is 5-10% longer than the seamless steel pipe, or even more, which reduces the steel consumption of the casing for 10,000 meters by 5-10%. Even at the same price, ERW casing virtually saves users 5-10% of the purchase cost.
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Straightening processing technology and operation steps of thick-walled seamless pipe

Date : 2022-01-11

Thick-walled seamless pipes are widely used in vehicles, airlines, crude oil, chemical plants, engineering construction, heating furnaces, military and other units, and have a major influence in the social economy, so they are called industrial production capillaries. With the development trend of my country\'s economy, the application field of thick-walled seamless steel pipes has continued to develop, the production scale and specifications have been greatly improved, and the demand for product quality has become higher and higher. Therefore, thick-walled seamless steel pipes need to pass strict inspections before leaving the factory to meet application regulations.

The manufacturing level of thick-walled seamless steel pipes must consider the sales market and must be matched with corresponding machinery and equipment. In the whole process of forging and cold rolling of seamless spliced ​​thick-walled seamless steel pipes of stainless steel plates, one of the main performance indicators to consider the quality of seamless spliced ​​thick-walled seamless steel pipes produced and processed is parallelism. Most of the thick-walled seamless steel pipes must be straightened, and the oblique roller straightening has high performance and is the primary influence. However, for the deformation and deformation of the top of the thick-walled seamless steel pipe and the large-diameter thick-walled seamless steel pipe, the working pressure straightening method is often used.

The structure of the working pressure leveler is simple and flexible. Due to the lack of theoretical basis research on the technicality of work pressure correction, all the time, the old masters of the workers have been constantly experimenting and correcting them based on their work experience. The work pressure correction precision is poor, high efficiency is low, and labor efficiency is high. Therefore, analyzing the deformation behavior of the thick-walled seamless steel pipe in the whole process of straightening, and accurately measuring the straightening stroke arrangement is to ensure the straightening quality of the thick-walled seamless steel pipe and improve the high efficiency of straightening, and design a plan to produce a fully automatic straightening machine. prerequisites.

Calculating the straightening stroke arrangement for thick-walled seamless steel pipes is the core technology of the automatic straightening machine for thick-walled seamless steel pipes. For the current working pressure correction of thick-walled seamless steel pipe, the precision of the schedule is low, it must be continuously corrected, and the high efficiency is low. According to the basic theory of ductility, the work The mathematical analysis model of the load deflection value in the process can be used to simply calculate the corrective stroke arrangement of the thick-walled seamless steel pipe. The flattening deformation of the cross section is a common problem in the whole process of working pressure straightening of thick-walled seamless steel pipes, which seriously affects the production quality of thick-walled seamless steel pipes. Creating an accurate cross-sectional flattening mathematical analysis model can reasonably refer to the practical activities of engineering projects and complete production and processing, which is of key practical significance for improving yield.
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ASTM Standard Seamless Tube Impact Test

Date : 2022-01-18

The impact toughness of ASTM standard seamless tube reflects the resistance of the metal to the external impact load. It is generally expressed by the impact toughness value (ak) and the impact energy (Ak), whose units are J/cm2 and J (joules) respectively. 

Impact toughness or impact energy test (referred to as \"impact test\") is divided into three types: normal temperature, low temperature and high temperature impact test due to different test temperatures; according to the shape of the sample notch, it can be divided into \"V\"-shaped notch and \"U\" There are two types of notch impact tests.

Impact test: use a sample of a certain size and shape (10×10×55mm) (with a \"U\" or \"V\"-shaped notch in the middle of the length direction, the notch depth is 2mm) under the impact load on the specified testing machine. Experiment with broken at the notch.

A. Shock absorption work Akv(u) The work absorbed when a metal pattern with a certain size and shape is broken under the action of shock load. The unit is Joule (J) or Kgf.m.

B. The quotient of the impact toughness value akv(u) divided by the cross-sectional area of the bottom of the sample at the notch. The unit is Joule/cm2 (J/cm2) or kilogram force.m/cm2 (Kgf.m/cm2).

The normal temperature impact test temperature is 20±50C; the low temperature impact test temperature range is <15~-1920C; the high temperature impact test temperature range is 35~10000C.

The cooling medium used in the low temperature impact test is generally non-toxic, safe, non-corroding metal and non-solidifying liquid or gas at the test temperature. Such as absolute ethanol (alcohol), solid carbon dioxide (dry ice) or liquid nitrogen atomizing gas (liquid nitrogen).
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API casing hydrotest pressure test

Date : 2022-08-24

API oil casing is a steel pipe used to support the wall of oil and gas wells to ensure the normal operation of the entire oil well during the drilling process and after completion.

The hydrostatic pressure test of casing pipe is an indispensable part of the production process of the steel pipe. Its role is to test the anti-leakage performance of the steel pipe under standard test pressure and regulation time. Like radiographs, ultrasonics, and other flaw detection techniques, it is an important means of testing the overall quality of steel tubes.

The popular description is to fill the pipe with water and test its ability to maintain the specified pressure without leaking or breaking under pressure. Its operations include three steps: flushing, pressure testing and water control.

API 5CT standard for hydrostatic pressure test:

1. The hydrostatic pressure test value of coupling and threaded pipe is the lowest value of the hydrostatic test pressure of the flat end pipe, the maximum hydrostatic pressure test pressure of the coupling, and the internal pressure leakage resistance, but the standard maximum pressure is 69MPa and the pressure is calculated. The value is generally rounded to the nearest 0.5 MPa.
2. According to API requirements, the hydrostatic test pressure measuring device should be calibrated within 4 months before each use.
3. If the customer has special requirements, a higher pressure test pressure can be selected.
4. Hydrostatic pressure test Leakage is the basis for rejection.
5. Except where otherwise agreed between the purchaser and the manufacturer, hydrostatic pressure testing is not required for coupling blanks, coupling materials, nearby materials, or Q125 steel pup joints.
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Steel pipe dimensions & sizes chart

Date : 2022-08-29

Steel Pipe Dimension 3 Characters:
A completely description for steel pipe dimension includes outer diameter (OD), wall thickness (WT), pipe length (Normally 20 ft 6 meter, or 40 ft 12 meters).

Through these characters we could calculate the pipe weight, how much pressure pipe could bear, and the cost per foot or per meter.
Therefore, that’s why we always need to know a right pipe size.

Steel Pipe Dimensions Chart

Pipe Schedule Chart unit in mm as below, view here for Pipe Schedule Chart in inch.

\"Steel


Dimension standards for steel pipe
There are different standards to describe the steel pipe size, OD and wall thickness. Mainly are ASME B 36.10, ASME B 36.19.

Relevant standard specification ASME B 36.10M and B 36.19M
Both ASME B36.10 and B36.19 are the standard specification for the dimensions of the steel pipe and accessories.

ASME B36.10M
The standard covers the standardization of steel pipe dimensions and sizes. These pipes includes seamless or welded types, and applied in high or low temperature and pressures.
The pipe distinguished from tube (Pipe vs Tube), here the pipe is specially for pipeline systems, fluids (Oil and gas, water, slurry) transmissions. Use the standard of ASME B 36.10M.
In this standard, the pipe Outer Diameter smaller than 12.75 in (NPS 12, DN 300), pipe actual diameters is larger than NPS (Nominal Pipe Size)or DN (Nominal Diameter).

On the hand, for steel tube dimensions, the actual outside diameter same with pipe number for all sizes.

What is Steel Pipe Dimensions Schedule?
Steel pipe schedule is a indicating method represented by ASME B 36.10, and also used in many other standards, marked with “Sch”. Sch is the abbreviation of schedule, generally appearing in the American steel pipe standard, which is a prefix of a series number. For example, Sch 80, 80 is a pipe number from chart/table ASME B 36.10.

“Since the steel pipe main application is to transport the fluids under pressure, so their internal diameter is their critical size. This critical size is taken as nominal bore (NB). Therefore, if steel pipe carry the fluids with pressure, it is very important that pipe shall have enough strength and enough wall thickness. So wall thickness is specified in Schedules, which means the pipe schedule, abbreviated as SCH. Here ASME is the given standard and definition for the pipe schedule.”

The pipe schedule formula:
Sch.=P/[ó]t×1000
P is the Designed pressure, units in MPa;
[ó]t is Allowable stress of materials under design temperature, Units in MPa.

What does SCH mean for the steel pipe dimensions?
As describing the steel pipe parameter, we usually use the pipe schedule, It is a method that represent pipe wall thickness with number. Pipe schedule ( sch. ) is not a wall thickness, but a wall thickness series. Different pipe schedule means different wall thickness for the steel pipe in the same diameter. The most frequently indications of schedule are SCH 5, 5S, 10, 10S, 20, 20S, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160. The larger the table number, the thicker the surface pipe wall, the higher the pressure resistance.

Schedule 40, 80 steel pipe dimension means
If you are new in pipe industry, why you always see a schedule 40 or 80 steel pipe everywhere? What kind of material for these pipes?
As you have read above articles you know that Schedule 40 or 80 represent a pipe wall thickness, but why it always been searched by buyers?

Here is the reason:
Schedule 40 and 80 steel pipe as the common sizes that required in different industries, because of the generally pressure these pipes bear, they are always been asked for a large quantity.

The material standard for such thickness pipes has no limitations, you could ask sch 40 stainless steel pipe, like ASTM A312 Grade 316L; Or sch 40 carbon steel pipe, such as API 5L, ASTM A53, ASTM A106B, A 179, A252, A333 etc.

What is the Nominal Pipe Size (NPS)?
Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. Pipe size is specified with two non-dimensional numbers: a nominal pipe size (NPS) based on inches, and a schedule (Sched. or Sch.).

What is DN (Nominal Diameter)?

Nominal diameter also mean outside diameter. Because as the pipe wall is very thin, the outside and inside diameter of the steel pipe is almost same, so the average value of the both parameters is used as the name of the pipe diameter. DN (nominal diameter) is the general diameter of various pipe and pipeline accessories. The same nominal diameter of the pipe and pipe fittings can be interconnected, it has interchangeability. Although the value is close or equal to inside diameter of pipe, It is not the actual sense of the pipe diameter. The nominal size is represented by a digital symbol followed by the letter “DN”, and mark the unit in millimeters after the symbol. For example, DN50, a pipe with a nominal diameter of 50 mm.


Pipe Weight Class Schedule
WGT class (weight class) is an indication of the pipe wall thickness in early, but still used. It has only three grades, namely STD ( standard ), XS ( extra strong ), and XXS ( double extra strong ).
For the earlier production pipe, each caliber has only one specification, called standard tube (STD). In order to deal with high pressure fluid, the thickening pipe (XS) appeared. XXS ( double extra strong ) pipe appeared to handle the higher pressure fluid. People began to require the use of more economical thin-walled pipe until the emergence of new materials processing technology, then gradually appeared the above pipe number. The corresponding relation between pipe schedule and weight class, refer to ASME B36.10 and ASME B36.19 specification.

How to describe steel pipe dimensions and size correctly?
For example: a. Expressed as “pipe outside diameter × wall thickness”, such as Φ 88.9mm x 5.49mm (3 1/2” x 0.216” ).  114.3mm x 6.02mm (4 1/2” x 0.237”), length 6m (20ft) or 12m (40ft), Single Random Length (SRL 18-25ft), or Double Random Length (DRL 38-40ft).

b. Expressed as “NPS x Schedule”, NPS 3 inch x Sch 40, NPS 4 inch x Sch 40. Same size as above specification.
c. Expressed as “NPS x WGT Class”, NPS 3 inch x SCH STD, NPS 4 inch x SCH STD. Same size above.
d. There is another way, in North America and South America, usually use “Pipe Outer Diameter x lb/ft” to describe pipe size. As OD 3 1/2”,  16.8 lb/ft. lb/ft is pound per feet.

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Seamless steel pipe for fluid transportation

Date : 2022-09-08

Fluid seamless steel pipe is a kind of steel pipe used for fluid transportation.
A seamless steel pipe for fluid (fluid pipe) is a steel pipe with a hollow section and no welds from the beginning to the end. It is mainly used for conveying fluid pipelines in engineering and large-scale equipment.

Fluid seamless pipe production process:

Round tube billet→heating→piercing→three-roll skew rolling, continuous rolling or extrusion→tube removal→sizing (or reducing)→cooling→billet tube→straightening→hydraulic test (or flaw detection)→marking→warehousing .

Due to its low cost and high strength, fluid seamless pipes are widely used in fluid transportation in modern society. The fluid seamless pipe can also carry out anti-corrosion and thermal insulation treatment on the surface according to the needs of use conditions and actual construction conditions.
The length of the fluid seamless pipe can be made according to the needs of customers, the general length is between 6 and 12 meters, and the export steel pipe is within 6 meters. The fluid seamless pipe at the outlet also needs to be grooved, painted and capped.

The difference between structural seamless steel pipe and fluid seamless steel pipe:

Structural seamless steel pipe, this standard is applicable to seamless steel pipe for general structure and mechanical structure, and fluid seamless steel pipe standard is applicable to general seamless steel pipe for conveying fluid. The main difference between it and the structural seamless steel pipe is that the fluid seamless steel pipe is subjected to hydraulic test one by one or ultrasonic, eddy current and magnetic flux leakage inspection. Therefore, in the standard selection of pressure pipeline steel pipes, fluid seamless steel pipes should be used.

Manufacturing method:
① Generally, the temperature of boiler tubes is below 450 °C, and domestic tubes are mainly made of No. 10 and No. 20 carbon steel hot-rolled tubes or cold-drawn tubes.
② High-pressure boiler tubes are often used in high temperature and high pressure conditions, and the tubes will be oxidized and corroded under the action of high-temperature flue gas and water vapor. The steel pipe is required to have high lasting strength, high oxidation corrosion resistance, and good organizational stability.

Application:
①General boiler tubes are mainly used to manufacture water wall tubes, boiling water tubes, superheated steam tubes, superheated steam tubes for locomotive boilers, large and small smoke tubes and arch brick tubes, etc.
②High-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, gas guide tubes, main steam tubes, etc. of high-pressure and ultra-high-pressure boilers.
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Pickling, annealing and low temperature tempering of seamless steel tubes

Date : 2022-09-16

Pickling of seamless steel tubes is a very widely used method for removing grease. It uses the principle of emulsification, wetting and penetration of surfactants, and uses the mechanical peeling effect of acid to corrode metals to generate hydrogen to achieve the purpose of removing grease. Acidic cleaners can be used at low and medium temperatures. Generally, only liquid oil can be removed at low temperature, and oil and grease can be removed at medium temperature. Generally only suitable for soaking treatment.

Seamless steel tube before pickling

The purpose of annealing seamless steel tube is to eliminate structural defects, improve the structure, make the composition uniform and refine the grain, improve the mechanical properties of the steel, reduce the residual stress; at the same time, it can reduce the hardness, improve the plasticity and toughness, and improve the machinability. machinability. Therefore, annealing is not only to eliminate and improve the structural defects and internal stress left by the previous process, but also to prepare for the subsequent process. Therefore, annealing belongs to the heat treatment of semi-finished products, also known as preheat treatment. After a certain degree of cold deformation processing, the mechanical properties of the chilled seamless steel tube are improved. The deformation degree of the semi-cold state is smaller than that of the cold-processed carbon steel tube, and the mechanical properties are between the soft state and the cold state, which is suitable for light processing.

Unannealed seamless steel tube, annealed or not depends on the delivery status required by the customer

The structure obtained by low temperature tempering is tempered martensite. The purpose is to reduce the internal stress and brittleness of the quenched seamless steel tube under the premise of maintaining the high hardness and high wear resistance of the quenched seamless steel tube, so as to avoid cracking or premature damage during use. Mainly used for various high carbon cutting tools, measuring tools, cold stamping dies, rolling bearings and carburized parts, etc. The hardness after tempering is generally HRC58-6 medium temperature tempering (250-500 degrees). Fire trotter. Its purpose is to obtain high yield strength, elastic limit and high toughness of seamless steel tubes. Therefore, it is mainly used for the treatment of various springs and hot work dies. The hardness after tempering is generally HRC35-50.
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Surface treatment of the spiral pipe

Date : 2022-09-30

Spiral pipe derusting and anti-corrosion process:

Derusting is an important part of the anti-corrosion process of spiral welded pipe pipelines. At present, there are many derusting methods, such as manual derusting, sand blasting and pickling and so on. Among them, manual rust removal, mechanical rust removal and painting rust removal (anti-corrosion brushing oil) are relatively common rust removal methods. The following is a brief introduction to the specific operation requirements of these three rust removal processes by welded pipe manufacturers.

1) Manual rust removal
Use scrapers and files to remove the oxide skin and casting sand on the surface of the pipes, equipment and containers, and then use a wire brush to remove the rust on the surfaces of the spiral pipes, equipment and containers, then polish them with sandpaper, and then use cotton silk to remove them. Wipe clean.

2) Mechanical descaling
First remove the oxide skin and casting sand on the surface of the pipe with a scraper and a file; then one person is in front of the rust remover, and one person is behind the rust remover, and the pipe is placed in the rust remover repeatedly to remove rust until the metal color is exposed; brush Before oiling, wipe it again with cotton silk to remove the floating ash on its surface.

3) Anti-corrosion brush oil
Pipes, equipment and container valves are generally subjected to anti-corrosion and oil brushing according to the design requirements. When there are no design requirements, the following regulations shall be followed:

1. Exposed pipes, equipment and containers must be painted with an anti-rust paint first, and then painted with two top paints before handover. If there are requirements for thermal insulation and anti-condensation, two anti-rust paints should be painted;

2. Two coats of anti-rust paint should be applied to concealed pipelines, equipment and containers. The second coat of anti-rust paint must be painted after the first coat of paint is completely dry, and the consistency of the anti-rust paint should be appropriate;


3. When the buried pipeline is used as the anti-corrosion layer, if the construction is carried out in winter, it is advisable to use rubber solvent oil or aviation gasoline to dissolve 30 A or 30 ethyl petroleum asphalt. Two kinds:
① Manual brushing: Manual brushing should be applied in layers, each layer should be reciprocated, criss-crossed, and the coating should be kept uniform without missing or falling;
②Mechanical spraying: When spraying, the sprayed paint flow should be perpendicular to the spraying surface. When the spraying surface is flat, the distance between the nozzle and the spraying surface should be 250-350mm. If the spraying surface is an arc surface, the distance between the nozzle and the spraying surface should be about 400mm. , When spraying, the movement of the nozzle should be uniform, the speed should be maintained at 10 ~ 18m/min, and the compressed air pressure used for spray painting should be 0.2 ~ 0.4MPa.
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The Development Direction of Spiral Welded Pipe

Date : 2022-09-30

Due to the increasing bearing pressure of the pipeline, the use conditions are becoming more and more severe, and the service life of the pipeline should be extended as much as possible. In order to improve competitiveness, carbon steel tube manufacturers should research and innovate in what aspects, and what are the main development directions of spiral welded pipes?

(1) Production of large diameter thick-walled pipes to improve pressure resistance;
(2) Design and produce steel pipes with new structures, such as double-layer spiral welded pipes, that is, double-layer pipes are welded with strip steel with half the thickness of the pipe wall, which not only has higher strength than single-layer pipes of the same thickness, but also does not appear brittle failure;
(3) Develop new steel grades, improve the technical level of smelting technology, and widely use controlled rolling and post-rolling residual heat treatment technology to continuously improve the strength, toughness and welding performance of the pipe body;

(4) Vigorously develop coated pipes, such as coating the inner wall of the pipe with an anti-corrosion layer, which can not only prolong the service life, but also improve the smoothness of the inner wall, reduce fluid friction resistance, reduce wax accumulation and dirt, reduce pigging times, and reduce maintenance cost.


The spiral welded pipe plays a great role in conveying gas and transportation. With the planning and construction of a number of major pipeline projects at home and abroad, high value-added products such as large-deformation pipeline steel, high-strength hot-simmering elbows, and thick-specification low-temperature pipe fittings have shown good market competitiveness and large market demand. However, domestic enterprises are relatively slow in developing this series of products. They should develop high-value-added large-deformation pipeline steel, steel for hot simmering and bending, steel for low-temperature pipe fittings for pipeline stations, and X100 straight seam suitable for industrial applications as soon as possible. Submerged arc welded pipe, spiral seam submerged arc welded pipe and hot simmered spiral welded pipe.

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How to remove rust from welded steel pipes?

How to remove rust from welded steel pipes?

Date : 2024-03-08

How to remove rust from welded steel pipes?

1. Mechanical grinding method
Mechanical grinding is one of the more common rust removal methods for welded steel pipes and is suitable for large-area rust removal. The specific operation steps are to first use a copper wire brush to remove the surface rust, and then use mechanical equipment such as an electric polisher to polish the steel pipe. What needs to be noted is that the grinding must be even and detailed, especially the joints, to achieve the rust removal effect while ensuring the surface quality.

2. Chemical rust removal method

Chemical rust removal method refers to the use of chemicals to reduce iron oxide into easily soluble amorphous matter to achieve the purpose of rust removal. This method is a comprehensive and thorough rust removal method. It is suitable for local rust spots on the pipe wall and a small amount of rust spots on the surface. However, the selection of chemical agents and soaking time need to be strictly controlled. Common rust removal agents include acids, alkalis, chelating agents, etc., which need to be selected according to actual conditions.


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3. Electrochemical rust removal method
The electrochemical rust removal method uses electrochemical reactions to react surface oxides with positively charged electrodes to achieve the purpose of rust removal. This method is simple to operate, has good rust removal effect, and does not damage the metal matrix of the steel pipe, but it requires special equipment and power supply. In addition, this method needs to control the current density and time to ensure the rust removal effect.

The above three methods all have their own advantages, disadvantages and scope of application, and the specific use should be selected according to the actual situation. In addition, you should also pay attention to the following points:

1. When using the mechanical grinding method, be sure to ensure that tools such as steel pipe copper wire brushes and polishers are clean to prevent secondary pollution caused by contact with rust.
2. When using chemical rust removal and electrochemical rust removal, you must master the relationship between the agent and the current time, and strictly abide by the process requirements to avoid accidents.
3. For steel pipes with deep rust spots on the surface, they need to be pre-treated by sandblasting, water cutting, etc., and then choose an appropriate rust removal method.
4. After rust removal, the steel pipe needs to be cleaned promptly and thoroughly to ensure that the inner surface of the pipe is uniform, smooth, clean and pollution-free.

In short, the choice of steel pipe rust removal method should be selected according to the specific environment and usage requirements. At the same time, we must also pay attention to personal safety and environmental protection, and contribute to ensuring our own health and the sustainability of the ecological environment.


Go here to learn more about \" Matters needing attention when purchasing welded steel pipes\"

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What is seamless square and rectangular tube?

What is seamless square and rectangular tube?

Date : 2024-03-08

What is seamless square and rectangular tube?

Seamless square and rectangular tube is a square tube with four corners. It is a square tube or rectangular tube formed by cold drawing or extrusion of seamless steel tube. Seamless square rectangular tube is a rectangular parallelepiped with a hollow cross-section and no seams around it. Tube.

What material are square tubes generally made of?
The material of square tubes is generally carbon steel square tubes and low alloy square tubes. Common carbon steel is divided into: Q195, Q215, Q235, SS400, 20# steel, 45# steel, etc.; low alloy steel is divided into Q345, 16Mn, Q390, ST52-3, etc. Common American standards include EN 10210, EN 10219, ASTM A500.

Forming process: Most square and rectangular steel pipes are unpacked, flattened, curled, and welded to form round pipes, which are then rolled into square pipes and then cut to the required length.


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Square tube sizes:

Square or rectangular tubes are steel pipes characterized by square or rectangular cross-sections. The measurement method of their external dimensions usually refers to the outer diameter of the pipe. The specific square tube size range is as follows:
1. Square tube outer diameter size range: 10×10mm-600×600mm;
2. Rectangular tube outer diameter size range: 10×20mm-600×400mm.
These size ranges are clearly specified in national standards, and special specifications of square and rectangular tubes can also be produced according to customer requirements.


Classification of square and rectangular tubes:

a. According to the production process, square and rectangular tubes are divided into: hot-rolled seamless square tubes, cold-drawn seamless square tubes, extruded seamless square tubes, and welded square and rectangular tubes.

b. Among them, welded square pipes are divided into:
1. According to the process - arc welding square tube, resistance welding square tube (high frequency, low frequency), gas welding square tube, furnace welding square tube
2. According to the welding seam - straight seam welded square pipe, spiral welded square pipe

c. Square tubes are classified according to cross-sectional shape:
1. Simple cross-section square tube - square square tube, rectangular square tube
2. Complex cross-section square tubes - flower-shaped square tubes, open-shaped square tubes, corrugated square tubes, special-shaped square tubes

What is the difference between seamless square tube and welded square tube?

Seamless square tubes are formed by cold drawing of seamless round tubes, while welded square tubes are formed by strip welding. This is a difference in process.
Secondly, the price of seamless square tubes is much higher. Due to the quantity limit of many non-standard specifications of welded square pipes, seamless delivery is faster.

Performance characteristics of square tube:

1. Seamless square tube is made by extruding seamless round tube. The plasticity of square tubes refers to the ability of metal materials to produce plastic deformation (persistent deformation) without destruction under load. The fatigue of square tubes means that many machine parts work under cyclic loads, and under such conditions the parts will fatigue.

2. The hardness of square tube is a measure of the softness and hardness of metal materials. At present, the commonly used method for measuring hardness in production is the indentation hardness method, which uses an indenter with a certain geometric shape to press into the surface of the metal material being tested under a certain load, and the hardness value is measured based on the degree of indentation. Commonly used methods for square tube hardness include Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and Vickers hardness (HV).

3. The impact toughness of square tubes refers to the load acting on the machine parts at a very high speed, which is called impact load. The metal\'s ability to resist damage under the impact load. Strength refers to the ability of a metal material to resist damage (excessive plastic deformation or fracture) under static load. Since the load acts in the form of tension, compression, bending, shearing, etc., the strength is also divided into tensile strength, compressive strength, flexural strength, shear strength, etc.

Uses of square and rectangular tubes:


Square and rectangular pipe is a widely used steel pipe material with many uses. The following are the main uses of square and rectangular tubes:

1.Construction industry
Square rectangular tube is a steel product commonly used in the construction industry. In building structures, square rectangular tubes can be used to manufacture components such as frames, supports, beams and columns. It has high strength and durability and can withstand a lot of heavy pressure and crushing. In addition, in construction, square and rectangular pipes are easy to process and weld, and are very suitable for on-site manufacturing and installation.
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Material selection and precautions for spiral welded pipes for bridge piling

Material selection and precautions for spiral welded pipes for bridge piling

Date : 2024-03-15

Bridge construction is an important part of infrastructure construction, and its engineering quality is directly related to traffic safety and the durability of the entire project. In bridge piling projects, the use of spiral welded pipes has received more and more attention. This article will delve into the advantages, material selection considerations and production processes of spiral welded steel pipes for bridge piling to help potential customers better understand and choose suitable spiral welded pipes.

Advantages of spiral welded pipes for bridge piling:

High strength: The spiral welded pipe has high compressive strength and tensile strength, and can withstand large pile foundation loads to ensure the stability of the bridge project.
Good load-bearing capacity: Spiral welded pipe has strong load-bearing capacity and can maintain good load-bearing performance under different geological conditions.
Simple structure: Compared with other piling methods, the bridge project using spiral welded pipe piling has a simple structure and is less difficult to construct.

High cost-effectiveness: Compared with other piling materials, spiral welded pipes are reasonably priced and have a short construction period, which can reduce the cost of the entire bridge project.


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Things to note when selecting spiral welded pipes for bridge piling:

Material: When purchasing, you should choose steel with high strength, good toughness and corrosion resistance, such as Q235B, Q345B, etc.
Specifications: Select the appropriate pipe diameter, wall thickness and length according to the actual needs of the bridge project to meet the piling needs.
Production process: High-quality spiral welded pipes should be made using advanced production processes, such as double-sided submerged arc welding technology, to ensure the uniformity of the steel pipe and the quality of the weld.
Testing and certification: When purchasing, you should pay attention to the product’s test report and related certifications to ensure the quality and performance of spiral welded pipes.

Production process of spiral welded pipe for bridge piling:

Material selection: Select the appropriate steel plate material and thickness according to project requirements.
Forming: The steel plate is formed into a spiral shape through an advanced forming machine to ensure that the steel pipe has a regular shape and precise dimensions.
Welding: Double-sided submerged arc welding technology is used to weld the spiral seams of the steel pipes to ensure good strength and sealing of the welds and ensure the overall performance of the spiral steel pipes.
Cutting: Cut the welded spiral welded pipe to the required length according to customer needs and actual project conditions.
Inspection: Strict quality inspection is conducted on the cut spiral welded pipes, including inspection of size, shape, weld quality, etc.
Anti-corrosion treatment: For bridge projects in special environments, spiral welded pipes can be treated with anti-corrosion, such as zinc spraying, paint, etc., to extend their service life.
Packaging and transportation: According to customer requirements, the finished spiral welded pipes are properly packaged to ensure that they are not damaged during transportation.

Summary: 

Spiral welded pipes for bridge piling have many advantages in bridge construction, such as high strength, good load-bearing capacity, and simple structure. In order to ensure the quality and performance of spiral welded pipes, you should pay attention to materials, specifications, production processes, testing and certification when purchasing. We hope this article can provide valuable reference for potential customers and help your bridge project proceed smoothly.


Click here to learn more: Spiral welded pipe manufacturing process
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Seamless carbon steel pipe materials and characteristics

Seamless carbon steel pipe materials and characteristics

Date : 2024-03-15

What is the material of seamless carbon steel pipe? What are the characteristics?

Seamless carbon steel pipe is a well-made pipe with excellent material and has a wide range of applications in the industrial field. Its material is mainly composed of carbon and iron, and is characterized by its high strength, excellent corrosion resistance and good weldability.


Seamless carbon steel pipe material:

The material of seamless carbon steel pipe is mainly composed of carbon and iron. Carbon is a basic element that has the characteristics of high hardness, high strength and good thermal conductivity, which allows seamless carbon steel pipes to withstand greater pressure and impact during use. Iron is the main component of steel. It has high ductility and good plasticity, allowing seamless carbon steel pipes to be easily processed and formed.


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Seamless carbon steel pipe characteristics:

1. One of the characteristics of seamless carbon steel pipes is their high strength. Because its material contains carbon, the hardness and strength of the steel pipe are greatly increased. The high strength of seamless carbon steel pipes allows them to withstand greater pressure and weight, so they are widely used in applications requiring higher strength.

2. Seamless carbon steel pipes also have excellent corrosion resistance. Since the material of carbon steel pipes contains a certain amount of chromium, the steel pipes have a self-healing oxide film layer that can effectively resist external oxidation, corrosion and other damage. This enables the seamless carbon steel pipe to work stably for a long time in harsh environments, extending the service life of the steel pipe.

3. Seamless carbon steel pipes also have good weldability. The composition and structure of carbon steel pipes enable them to be well connected and welded to other metal materials. This allows seamless carbon steel pipes to be easily connected to other pipes and equipment, improving work efficiency and convenience.

To sum up, the material of seamless carbon steel pipe is mainly composed of carbon and iron, which is characterized by high strength, excellent corrosion resistance and good weldability. This makes seamless carbon steel pipes widely used in industrial fields and has become an indispensable pipe material in many industries. Seamless carbon steel pipes, with their excellent material quality and stable performance, provide reliable solutions for various industries and have become an indispensable part of modern industrial fields.


Go here to learn more about \" welded steel pipe vs seamless steel pipe\"

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How to choose the right hollow square tube?

Date : 2024-03-19

When deciding which hollow square tube to choose for your project, here are seven factors you must consider before purchasing. We hope that our tips and advice will help you make an informed decision and ensure you buy the best hollow square tube for your needs.

1. Clarify usage requirements
First of all, it is necessary to clarify the use requirements of hollow square and rectangular tubes. For example, there are different requirements in construction, machinery, furniture and other fields.

2. Determine the required materials

First, determine the materials needed to meet the usage environment and performance requirements. Pipes can be made from different materials, including steel, stainless steel, aluminum, copper and brass. Each material has its properties and benefits. For example, steel pipes are strong and durable and suitable for structural applications. Aluminum pipe, on the other hand, is lightweight and corrosion-resistant, making it ideal for outdoor projects.


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3. Determine the required size specifications
After determining the required materials, the next step is to determine the appropriate specifications of the required hollow square tube, including size, wall thickness and other parameters. The size of the pipe depends on the specific application. For example, if you are using pipe for structural purposes, you will need to choose a size that can support the weight of the structure. On the other hand, if you are using pipes to make furniture, you need to choose sizes that are compatible with the design of the furniture.

4. Consider shape
Hollow square tubes come in different shapes, including round tube, square tube and rectangular tubes. The shape you choose depends on the specific application. For example, if you are using pipes for decoration, choose a more aesthetically pleasing shape, such as round pipes. On the other hand, if you are using pipe for structural purposes, choose a more angular shape, such as hollow square pipe.

5. Check quality
Choosing high-quality hollow square tube for your project is important to ensure durability and longevity. Check the quality of pipes by inspecting welds, seams and surface treatments. High-quality pipe should have clean, even welds, no bubbles, smooth seams, and a consistent finish. If you need more clarification on pipe quality, ask your pipe supplier for more information or look online for reviews and testimonials.

6. Consider the cost
Finally, consider the cost of hollow square pipe. The price of hollow square pipe may vary depending on the material, size, shape and quality of the pipe. It’s best to shop around and compare prices from different suppliers to get the best value for money. However, it is important not to compromise on quality just to save money.


Go here to learn more \" Square tube size\"

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Heat treatment methods of carbon steel pipes

Date : 2024-03-26

The heat treatment methods of carbon steel pipes (cs pipe) include annealing, normalizing, quenching, tempering, etc. Different heat treatment methods can change the mechanical properties such as hardness and toughness of steel and change its chemical properties to meet the needs of different fields.

1. Annealing treatment

Annealing treatment refers to a heat treatment method in which carbon steel pipes are heated to a certain temperature and slowly cooled. This method can uniformize the internal structure of the steel, relieve the internal stress of the steel, reduce the hardness, and improve the toughness and plasticity. At the same time, it can also improve the processing performance and corrosion resistance of steel. For some carbon steel pipes that require deep drawing, cold shearing, cold drawing and other cold processing, annealing is an essential step. The annealing temperature and time of different carbon steel pipes are also different and need to be adjusted according to the specific material.


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2. Normalizing treatment
Normalizing treatment refers to a heat treatment method in which carbon steel pipes are heated to a certain temperature and quenched in air. This method can improve the hardness and wear resistance of the steel, while also improving the tensile strength and load-bearing capacity of the steel. Generally speaking, high alloy steel needs to be normalized to meet some high strength and high hardness requirements. However, due to the high stresses in normalized steel, tempering is often required to relieve the stresses.

3. Quenching treatment
Quenching treatment refers to a heat treatment method in which carbon steel pipes are heated to a certain temperature and quenched in water, oil or other quenching media. This method can improve the hardness, wear resistance and toughness of the steel, but it easily produces large stresses, and tempering is often required to relieve these stresses. The quenching method and temperature also need to be selected according to different steel materials and needs.

4. Tempering treatment
Tempering treatment refers to a heat treatment method in which the quenched carbon steel pipe is heated to a certain temperature again and slowly cooled. This method can relieve the stress of the steel and adjust the hardness and toughness of the steel to optimize the performance of the steel. Generally speaking, the temperature and time of tempering treatment need to be selected according to different steel materials and needs.

Conclusion:

The above are several common carbon steel pipe heat treatment methods and their functions. Different treatment methods can optimize the performance of steel and meet the needs of different fields. When performing heat treatment, different treatment methods and parameters need to be selected according to specific conditions.


Go here to learn more about \"Carbon steel tube material\" or \" Carbon steel vs Stainless steel \"

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Is the welded pipe hot rolled or cold rolled?

Date : 2024-03-26

Welded pipe production process:
Welded pipe, also known as welded steel pipe, is a steel pipe made by applying welding technology to roll steel plate or strip into a tube shape, and then flattening, crimping, welding and leveling. Generally, the production processes of welded pipes are divided into two types, namely cold rolling and hot rolling.

Composition and characteristics of welded pipe:
The raw materials of welded pipes are mostly black steel plates, whose main components are carbon and manganese. During the welding process, the composition of the welded joint changes, and carbon and other elements undergo chemical reactions. Therefore, the welded area is usually more susceptible to corrosion than the non-welded area.

Welded pipes are widely used because of their light weight, low price, high strength, and easy processing. However, due to changes in the welding process and the influence of the pipe composition, the physical properties of welded pipes sometimes have certain deficiencies.


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The difference between hot rolling and cold rolling of welded pipes:
1. Hot rolling
Hot rolling is a process processed at high temperatures. At high temperatures, steel has good plasticity and plasticity and can quickly adapt to millisecond-level deformations. Therefore, hot rolling can produce thick-walled welded pipes with a smooth surface. However, processing at high temperatures will cause changes in the crystal structure of the material, resulting in a decrease in fracture toughness and limited processing accuracy.

2. Cold rolling
Cold rolling is a process that takes place at room temperature. Because it is processed at room temperature, its processing accuracy is high and the toughness and stretchability of the material will not be reduced due to processing, so the cold-rolled welded pipe also has good strength and toughness. However, the production process of cold-rolled welded pipes is slow and the cost is relatively high.

Application differences between hot rolling and cold rolling:
Due to its fast production speed and smooth surface, hot rolling has a wide range of applications. Hot-rolled welded pipes are commonly used in construction, machinery, petroleum and chemical industries. Due to its good strength and deviation, cold-rolled welded pipe is usually used to manufacture high-precision parts, such as automobiles, electrical appliances, precision instruments and other fields.

Summarize:

This article introduces the production process and ingredients of welded pipes, and explains its characteristics and the differences between cold rolling and hot rolling, so that readers can have a deeper understanding of welded pipes. In the actual selection, it needs to be considered according to the specific situation in order to achieve the best application effect.


Go here to learn more about \" seamless vs welded pipe\"

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Square Tube vs. Round Tube: Which One is Better? How to Choose?

Date : 2024-03-26

There are two types of steel pipes: square tubes and round tubes. With different shapes and specifications, their performance parameters will also be different. So, which one is better, square tube or round tube? How to choose? Let’s take a look at the carbon steel tube manufacturers.

What is a square tube?
Square tube is a square polygonal tube with regular shape and structure, which is easy to cut and convenient to transport and connect. The advantages of square tubes are not only their appearance, but also their long service life, corrosion resistance, high strength, and good weldability. They can also be processed and processed according to different requirements. Therefore, square tubes have wide application value in installing urban sculptures, building structures, road guardrails, etc.

What is a round tube?

Round tube is a steel pipe with a circular cross-section. It has a regular structure and is more suitable for bending, folding and other processing methods. It is also relatively strong and not easily damaged. The round pipe has high pressure resistance, long service life, good corrosion resistance and waterproof performance, and is also more beautiful in appearance. Therefore, round pipes are also widely used in fields such as building structures, mechanical processing, and oil field development.


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Which one has greater bending strength, square tube or round tube?

Square tubes are larger. Because the calculation formula of the pipe resistance moment is to divide the moment of inertia value (the cross-sectional area times the pipe height), so in the case of the same cross-sectional area, thickness and pipe height, it is only necessary to compare the moment of inertia values of the square tube and the round tube, that is Yes, the moment of inertia of the square tube is 86.68 cm to the fourth power, and that of the round tube is 51.05 cm to the fourth power. In comparison, the moment of inertia of the square tube is larger, so the bending strength of the square tube will also be bigger.

How to choose between square tube and round tube:

1. Determine according to the purpose

There are many uses for square tubes and round tubes. When choosing, construction workers need to determine based on the actual purpose. For example, when installing guardrails, it is usually recommended to use round tubes. First, because the shape of round tubes is more rounded and has better aesthetic performance. Secondly, the guardrail does not require high load-bearing capacity, so round pipes can also meet the requirements and the price is economical.

2. Determine according to project requirements

If it is a relatively large project, it needs to be installed in strict accordance with the engineering design requirements, including the shape, size and thickness of the steel pipe, which must meet the requirements, so as to ensure that the project quality meets the standard. If it is a small project at home, it is generally recommended to choose slightly thicker materials.

3. Determine according to load-bearing requirements

If pipes are used as support materials, the load-bearing requirements for the pipes will be relatively high. When choosing, it is generally recommended to choose square pipes, which will have better load-bearing effects, especially the surrounding support points, so that the manufacturing effect will be better. 

Advantages and disadvantages of square tubes and round tubes:

1. Advantages and disadvantages of square tubes
Advantages: The square tube has high strength and good rigidity, and can withstand large pressure and weight and is not easily deformed, making it more suitable for some occasions that require load-bearing. Moreover, square tubes are generally square or rectangular, which is conducive to overlapping and connection during installation, and is more convenient to install.

Disadvantages: Compared with round tubes, the stress-bearing surface of square tubes is relatively small, and the bearing capacity has certain limitations. In addition, its performance in bending and torsion is poor, and it is prone to problems such as deformation and cracking.

2. Advantages and disadvantages of round tubes
Advantages: The stress-bearing area of the round tube is relatively large, and it can evenly distribute the load and make bends. When subjected to large pressure and weight, round pipes have better resistance to deformation and are more suitable for bending processing.

Disadvantages: Due to the small connection area of round tubes, the bearing capacity will attenuate and deform after being used for a period of time, and the connection points of the pipes need to be strengthened. In addition, due to the influence of the edge angle during installation, the connection is prone to cracks and is difficult to connect, and non-destructive testing is required to ensure the connection quality.

Application scenarios of square tubes and round tubes:
From the above advantages and disadvantages, it can be seen that the advantages and disadvantages of square tubes and round tubes are offset, and the scenarios in which they are used are also different. Generally speaking, square tubes are more suitable for use in building structures and vehicle manufacturing that require vertical load-bearing; round tubes are more suitable for bending and bending, such as furniture manufacturing, machinery manufacturing, etc.

Conclusion:

Square tubes and round tubes are two different types of tubes. When selecting tube materials, you should comprehensively consider square tubes and round tubes based on specific usage scenarios and design requirements, and choose the tube material that is more suitable for your own use requirements. In addition, we also need to pay attention to the standards and specifications for material selection and ensure that the selected pipes meet the relevant standards and specifications to ensure the use effect.


Read more: How to Choose the Right Hollow Square Tube for your Project?

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The key to improving structural strength of square and rectangular tubes

Date : 2024-04-12

Analyze the key to improving the structural strength of square tubes and rectangular tubes. This is because square rectangular tubes have good bending resistance and stability.

With the development of the economy of the times, various small and medium-sized enterprises have begun to spring up like mushrooms after a rain. However, for the construction of factories of small and medium-sized enterprises, if the general building structure is used, it will bring a lot of economic expenditure to the enterprise. Therefore, The emergence of square and rectangular tubes eliminates these disadvantages. Its various characteristics meet the needs of small businesses for factory construction, and it is a good choice for large simple factories.


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Square and rectangular tube is a common engineering material, usually made of steel or aluminum alloy. Its main feature is that it has four right-angled sides and is shaped like a square. This special geometric shape enables the square rectangular tube to effectively disperse these forces when subjected to bending, torsion or compression, thereby improving the stability of the structure and its ability to resist damage. The price of this kind of steel is relatively cheap, and it is suitable for large-scale purchases by general enterprises. At the same time, it is the most common material for square and rectangular pipes. Its structure is simple, so the price of square and rectangular pipes made from it is also higher than that of ordinary pipes. The materials are more favorable and are more suitable for large-scale purchases during the construction process. They are very suitable for the requirements of small and medium-sized enterprises for factory buildings and basic construction materials.

Compared with other shapes of pipes, such as circular (seamless pipe) or oval, square and rectangular tubes can withstand greater stress under the same cross-sectional area. This is because when a force acts on a rectangular section, the force will be evenly distributed across all four corners rather than concentrated in the center, which helps prevent deformation and cracking.

In addition, square and rectangular tubes are rolled from strip steel. The manufacturing process is relatively simple and the cost is low. They are very suitable for mass production and procurement. They also have great advantages in terms of price and can support objects well during use. , so it has been widely used in many engineering applications. For example, square and rectangular tubes can be seen in building structures, bridges, vehicles, and mechanical components.

In short, due to its unique geometric shape and excellent mechanical properties, square and rectangular tubes have become one of the keys to improving structural strength. Through reasonable design and use, its advantages can be fully utilized and the safety and reliability of the project can be improved.
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Seamless tube application scope

Date : 2024-04-12

Seamless tube & tubing is a steel pipe with a variety of excellent properties and is widely used in various fields. The following will introduce the scope of application of seamless steel tubes and their applications in different fields.

1. Petrochemical industry

Seamless tubes are widely used in the petrochemical industry and are mainly used to transport high temperature, high pressure, flammable, explosive or corrosive media. For example, petroleum cracking pipes, fertilizer pipes, hydraulic support pipes, etc. These seamless steel pipes have the characteristics of high strength, high toughness and corrosion resistance, and can meet the high material requirements of the petrochemical industry.

2. Machinery manufacturing industry

Seamless tubes are also widely used in the machinery manufacturing industry, such as automobiles, ships, aviation, nuclear industry and other fields. These industries have very high requirements on the strength, toughness, corrosion resistance and precision of materials. Seamless steel pipes can meet these requirements and have good processing performance and connection performance.


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3. Electric power industry

Seamless tubes are mainly used in the power industry to manufacture key equipment such as boilers and steam turbines. The manufacture of these equipment requires high temperature, high pressure, high strength materials, and requires the materials to have good corrosion resistance and stability. Seamless steel pipes have these characteristics and are widely used in the power industry.

4. Construction industry

Seamless tubes are also widely used in the construction industry, mainly used in the construction of high-rise buildings, bridges, tunnels and other infrastructure. These buildings need to withstand greater pressure and gravity, and require materials with good toughness and durability. Seamless steel pipes have these characteristics and can meet the needs of the construction industry.

5. Transportation industry

Seamless tubes are also widely used in the transportation industry, such as railways, highways, waterways and other fields. These fields have very high requirements for material strength, toughness, corrosion resistance and lightweight. Seamless steel pipes can meet these requirements and have good processing performance and connection performance.

In summary, seamless tubes are widely used in various fields, and their excellent performance and high cost performance enable them to perform well in various situations. With the continuous advancement of technology and changing market demands, the application prospects of seamless steel tubes will be broader.


Go here to learn more: The use and scope of application of seamless carbon steel pipe

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Manufacturing process and application of large diameter spiral welded pipe

Date : 2024-04-19

Large-diameter spiral welded pipe is an important industrial pipe, widely used in petroleum, natural gas, chemical industry, construction and other fields. It has the characteristics of high strength, corrosion resistance and good pressure resistance, and has become an important part of modern engineering construction. This article will reveal to you the manufacturing process and application areas of large-diameter spiral welded pipes.

Manufacturing process of large diameter spiral welded pipe:

The manufacturing process of large-diameter spiral welded pipes requires multiple stages. First of all, high-quality steel plates are selected as raw materials, and through processes such as cutting, bending and pre-bending, a plate with a certain arc is formed. Then, the plates are welded, using a spiral welding process to roll the plates into a tube shape through the action of high temperature and pressure. Next, the pipe body is shaped and straightened to ensure that the geometry and size of the pipe meet the standard requirements. Finally, surface treatments such as rust removal and painting are carried out to improve the corrosion resistance of the pipe.


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Application fields of large diameter spiral welded pipe:

In the oil and gas industry, it is used to transport oil, gas and liquids and undertakes important pipeline transportation tasks.
In the chemical industry, large-diameter spiral welded pipes are widely used in chemical equipment and pipeline systems to transport various chemical media.
In addition, large-diameter spiral welded pipes are also used in urban construction and infrastructure construction, such as bridges, tunnels, drainage systems, etc. Its high strength and durability make it an indispensable material in these engineering projects.

In addition to the above application fields, large-diameter spiral welded pipes are also widely used in marine engineering, mining engineering, environmental protection engineering and other fields. In marine engineering, it is used in submarine oil and gas pipelines, offshore drilling platforms, etc. In mining engineering, large-diameter spiral welded pipes are used to transport ores and tailings. In environmental protection projects, it is used in wastewater treatment and exhaust gas emission pipelines.

To sum up, large-diameter spiral welded pipe is an important industrial pipe with a wide range of applications. Its manufacturing process goes through multiple links to ensure the quality and performance of the pipe. In the fields of petroleum, natural gas, chemical industry, construction and other fields, large-diameter spiral welded pipes play an important role, providing reliable support for the smooth progress of various engineering projects.


Go here to learn more: Matters needing attention when purchasing welded steel pipes

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Reasons for cracking of cold drawn seamless tubing

Date : 2024-04-19

The reasons for cracking of cold drawn seamless tubing may include the following aspects:

1. Material problem.
The quality of the raw materials is not up to standard. For example, the hardness, strength, toughness and other properties of the material do not meet the usage requirements, or there are defects such as inclusions and bubbles in the material. These will affect the performance of the material and cause the steel pipe to crack.

a. Inclusion problem: Inclusions are a form of impurities in cold-drawn seamless tubes. When the volume of inclusions is too large, it will affect the strength and plasticity of the steel pipe, leading to cracks.

b. Bubble problem: Bubbles are formed during the manufacturing process. The presence of bubbles will reduce the strength and stiffness of the material, leading to cracks.


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2. Manufacturing process problems.
a. Problem of excessive cold drawing: When cold drawing is excessive, it will cause the steel pipe to crack. This is because excessive cold drawing causes excessive stress inside the steel pipe, which leads to cracking.
b. Improper control of the steel pipe stretching process: Improper control during the steel pipe stretching process will lead to stress concentration, which may lead to cracks.
c. Production process problems: There are unreasonable aspects in the production process, such as traditional methods such as mold aging, which can also cause steel pipes to crack.

3. Processing issues.
Such as uneven stretching, processing speed, pressure, improper use of coolant, etc., these may cause uneven stress inside the steel pipe, thereby forming cracks.

4. Equipment problems. 

Wear and design defects of processing equipment may also cause steel pipes to be unevenly stretched or squeezed during processing, causing stress concentration and leading to cracks.


5. External factors.
If the processing environment conditions are harsh (such as excessive temperature, humidity) or wear and tear, these may cause the cold-drawn steel pipe to crack.

To sum up, there are many reasons for the cracking of cold-drawn seamless tubes, including materials, manufacturing processes, processes, equipment, and external factors. These factors need to be strictly controlled during the processing process to reduce or avoid the occurrence of such defects. 


Tips: ASTM A106 seamless pressure pipe (also known as ASME SA106 pipe) is commonly used in the construction of oil and gas refineries, power plants, petrochemical plants, boilers, and ships where the piping must transport fluids and gases that exhibit higher temperatures and pressure levels.

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Seamless pipe maintenance and storage methods

Date : 2024-04-26

Seamless pipe & tube (SMLS) maintenance and storage methods:

1. Anti-rust treatment
Seamless steel pipes are susceptible to oxidation, corrosion and other factors during the production, transportation and storage processes, so they must be rust-proofed. Commonly used anti-rust methods include spraying anti-rust paint, coating with anti-rust oil, surface galvanizing, etc. When choosing an anti-rust method, the choice should be based on the application environment and service life of the seamless steel pipe.

2. Regular inspection

In order to ensure the quality and service life of seamless pipes, they need to be inspected regularly. The inspection content includes appearance, size, physical performance, etc. If problems such as deformation, cracking, corrosion, cracks, etc. are found in seamless steel pipes, they should be repaired or replaced in time.


seamless pipe maintenance and storage


3. Storage environment
During the storage process of seamless pipes, it is necessary to pay attention to environmental hygiene, ventilation, drying and other factors. First, the storage environment should be kept dry to prevent seamless steel pipes from being exposed to moisture for a long time; secondly, attention should be paid to ventilation to prevent seamless steel pipes from being stacked together and unable to ventilate; finally, the storage area should be kept sanitary to avoid debris and dust. etc. will cause pollution to seamless pipes.

4. Avoid collision and friction
Seamless pipes are susceptible to collision and friction during transportation, loading and unloading, so collision and friction need to be avoided. During transportation, loading and unloading, attention should be paid to the use of appropriate equipment and tools to prevent friction and collision between seamless steel pipes and other items.

5. Regular cleaning and lubrication
Seamless pipes are easily affected by dirt during use, so they need to be cleaned regularly. At the same time, attention should be paid to lubrication of seamless steel pipes to avoid affecting the service life due to friction.

6. Precautions for storage and use

During the storage and use of seamless pipes, you also need to pay attention to the following matters: first, do not expose seamless pipes to sunlight for a long time; secondly, do not let seamless pipes be affected by deformation forces such as extrusion and bending; finally, Do not expose seamless steel pipes to oil, acid, alkali and other corrosive substances to avoid affecting the performance and life of seamless steel pipes.


Go here to learn more: Schedule 40 pipe

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Seamless pipe pickling passivation

Date : 2024-05-07

Introduction to pickling and passivation:
It is suitable for pickling and passivation treatment of carbon steel, stainless steel (seamless pipes), ferrous metals (castings, forgings, sheet metal parts, etc.) to remove rust and remove the black oxide layer to improve the anti-rust and anti-corrosion performance of the pipe surface. It is widely used in machinery manufacturing, petrochemical industry, transportation industry, metallurgy, electric power, textile printing and dyeing industry, mining, power plant, shipbuilding industry, machinery and other industries.

Seamless pipe (SMLS) pickling process: degreasing---washing---pickling---washing---sealing agent

Generally, there are two pickling methods for seamless steel pipes (carbon steel), as follows:
1. Sulfuric acid: dilute to a concentration of about 20%, heat to 60-65 degrees, and generally wash for 20-30 minutes

2. Hydrochloric acid: also dilute to a concentration of about 20%, and pickle directly at room temperature, usually for 20-30 minutes


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Features and advantages of pickling and passivation products:

1. Carbon steel pickling and passivating solution combines pickling and passivation into one. It does not require water washing to remove rust and black oxide layer, which greatly improves labor productivity.
2. The use and operation of the pickling passivation solution is very convenient. Tank washing and soaking are performed using small and medium-sized carbon steel pipe fittings. After treatment, the pipe surface has better corrosion resistance and rust prevention.
3. The use temperature is 5-30 degrees Celsius, and the pickling and passivation takes about 5-15 minutes to achieve the pickling effect.

The result after processing:

1. The treated carbon steel workpiece improves the corrosion resistance of carbon steel. The anti-rust effect is affected by many factors such as the workpiece material, surface condition, climate, air pollution conditions, dilution water quality, construction methods, workpiece stacking methods, etc.
2. The pickling passivation solution does not contain harmful substances, and the wastewater can be discharged directly after neutralization and has no impact on the environment.

Things to note when pickling and passivating seamless pipes:

1. Pickling and passivation operations must be carried out outdoors or in a well-ventilated room.
2. Operators should wear labor protection equipment before operating, and it is strictly forbidden to contact the skin with the pickling passivation solution. If accidentally touched, rinse immediately with clean water.
3. The containers and tools used for pickling and passivation treatment should be acid-resistant plastic tanks.
4. The treated residues and wastewater must be neutralized with lime milk or sodium hydroxide in time to prevent environmental pollution.
5. Do not operate under strong sunlight to prevent the stainless steel pickling passivation solution from drying out and affecting the passivation effect.
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Introduction to commonly used electrodes for welding steel pipes

Date : 2024-05-07

Commonly used electrodes for welding steel pipes (welded pipe):


1. Alkaline welding rod
Alkaline welding rod is currently the most commonly used welding rod for welding steel pipes. Its welding effect is good and the weld is strong, but it is prone to hydrogen embrittlement, so the welded steel pipe needs heat treatment. Alkaline welding rods are suitable for gas pipelines, oil pipelines, heat exchangers and other fields.

2. Coated welding rod

Coated welding rod is a commonly used anti-corrosion welding rod. It has good resistance to chemical attack and corrosion, and is widely used in welding stainless steel, acid-resistant steel, chemical equipment, oil refining equipment and other fields.


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3. Stainless steel welding rod
Stainless steel welding rods are suitable for welding stainless steel pipes and can ensure the performance and quality of the weld. It has the characteristics of high temperature resistance, corrosion resistance, and strong welds, and is widely used in shipbuilding, chemical industry, food and other fields.


How to choose the appropriate welding rod diameter specification?

When selecting welding rods for pipeline welding, you need to pay attention to the diameter specifications of the welding materials to ensure welding quality. Specifically, the selection of the diameter specification of the welding rod should be based on the following aspects:

1. Thickness of welding material
Generally speaking, the thicker the welding material, the thicker the welding wire diameter needs to be to ensure sufficient welding strength.

2. Welding stress
The greater the welding stress, the thicker the welding wire diameter needs to be selected to enhance the load-bearing capacity and stability of the weld.

3. Working location and welding conditions
Different operating positions and welding conditions require different electrode types and diameter specifications, so comprehensive considerations need to be made based on specific conditions during actual operation.


Things to note when purchasing welding rods:


1. Select the appropriate welding rod according to the material of the steel pipe.
Different steel pipes require different types of welding rods. Choosing the appropriate welding rod can ensure the quality and stability of the weld.

2. Determine the welding rod model according to the welding process.
Welding processes have different requirements for welding rods, and the appropriate welding rod model needs to be selected according to the specific situation.

3. Check the quality of the welding rod.
When purchasing welding rods, you should pay attention to check their quality to ensure the stability and reliability of welding quality.

Conclusion:

Welding steel pipes requires the correct selection of appropriate welding rods to ensure welding quality and stability. Select the appropriate welding rod model according to the specific conditions such as steel pipe material and welding process, and pay attention to checking the quality of the welding rod to ensure reliable welding quality.


Go here to learn more: Welded steel pipe production process

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What are the common pipe fittings and pipe connection methods?

Date : 2024-05-14

Common pipe fittings and pipe (welded pipe) connection methods include the following:

1. Threaded connection
This is a common connection method in which internal and external threads on pipes and fittings are screwed together to create a tight connection. It is simple and easy to operate and suitable for low pressure and small diameter piping systems.

2. Welding connection

Pipes and fittings are welded together to create a permanent connection. Common welding connection methods include butt welding, fillet welding and socket welding. Welded connections are commonly used in piping systems with high pressures and temperatures.


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3. Pressure connection
This is a common connection method that uses special pressure tools to compress sleeves or sleeves on pipes and fittings to form a sealed connection. Common pressure connection methods include ferrule connection, pressure sleeve connection and link connection. Pressure connections are suitable for piping systems made of many different materials.

4. Tension connection
Connections are made by clamping pipes and fittings together using bolts and nuts. This connection method is suitable for large pipelines and high-pressure pipeline systems.

5. Flange connection
Pipes and fittings are held together by pipe flanges and flange gaskets. Flange connections can be divided into flat welding flanges and butt welding flanges, which are usually used in large and high-pressure pipeline systems.

6. Clamp connection
Use clamps to clamp pipes and fittings together to create a connection. This type of connection is suitable for smaller diameter pipe systems such as water pipes and irrigation systems.

7. Quick connection
Quickly connect pipes and fittings to create a connection using quick connectors or quick connectors. This connection method is suitable for occasions that require frequent disassembly and replacement, such as liquid transmission and gas transmission.

The above are common ways of connecting pipe fittings and pipes. Choosing the appropriate connection method should be determined based on the specific pipeline system requirements and application scenarios. Before proceeding with installation, be sure to refer to relevant design and specification requirements and follow the installation guidelines provided by the manufacturer.


Go here to learn more: How are pipes and flanges connected?

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Quality inspection and quality control of square and rectangular tubes

Date : 2024-05-14

As an efficient, environmentally friendly and energy-saving building material, square and rectangular tubes are widely used in various construction projects. However, as the demand for square and rectangular tubes continues to increase in the market, quality problems have become increasingly prominent. In order to ensure the quality and reliability of square tubes and rectangular tubes, it is crucial to conduct strict quality inspection and quality control.

1. Specifications and parameters of square and rectangular tubes

Square rectangular tube is a steel tube with a square cross-section, which is processed from strip steel through multiple processes. Its main parameters include side length, wall thickness, length, etc. According to different uses, the specifications and parameters of square and rectangular tubes will also be different. Square and rectangular tubes have the characteristics of high strength, light weight, corrosion resistance and easy processing, and are widely used in bridges, buildings, automobiles, ships and other fields.


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2. Inspection standards for square and rectangular tubes

In order to ensure the quality of square and rectangular pipes, strict inspection standards need to be formulated. These standards mainly include the following aspects:

1) Appearance inspection: The appearance of square and rectangular pipes is required to have no obvious defects, such as scratches, cracks, rust, etc.
2) Dimensional inspection: Accurately measure the side length, wall thickness, length, etc. of the square rectangular tube to ensure that its dimensional accuracy meets the requirements.
3) Mechanical property inspection: Test the tensile strength, yield strength, elongation and other mechanical properties of the square rectangular tube to ensure that it meets relevant standards.
4) Chemical performance inspection: As needed, the chemical composition of the square tube is tested to ensure that it meets specific requirements.

3. Detection method of square and rectangular tubes

In order to achieve quality control of square rectangular pipes, effective detection methods need to be adopted. The following are several common square and rectangular pipe inspection methods:

1) Appearance inspection: Use visual inspection method to visually inspect the square and rectangular tubes in hand. If defects are found, they should be recorded and classified.
2) Dimensional inspection: Use accurate measuring equipment to inspect the dimensions of the square tube, such as micrometers, calipers, etc.
3) Mechanical property testing: Test the mechanical properties of the square tube through tensile testing, impact testing and other methods.

4) Chemical performance inspection: Collect samples of square and rectangular tubes and send them to the laboratory for analysis to obtain chemical composition and other relevant information.
5) Non-destructive testing: Use advanced non-destructive testing technology, such as ultrasonic testing, radiographic testing, magnetic particle testing, etc., to detect the inherent quality of square tubes.

4. Quality control of square and rectangular tubes

In order to ensure the quality of square and rectangular pipes, quality control needs to be carried out from the following aspects:

Design stage control: Design reasonable square and rectangular tube specifications, structures and manufacturing processes based on actual application requirements. Fully consider factors such as materials, manufacturing, transportation and use during the design stage to reduce possible quality problems.

Manufacturing process control: Develop a scientific manufacturing process and strictly control the raw materials, processing, welding, heat treatment and other aspects of the square tube. Strengthen the quality monitoring of key processes to ensure that the processing quality of each link meets the requirements.

Equipment control: Use advanced production equipment and testing equipment to ensure the accuracy and stability of the equipment to meet the processing and testing needs of square and rectangular tubes. Perform regular maintenance and calibration of equipment to ensure normal operation of the equipment.

Personnel quality control: Strengthen the training and management of square tube manufacturing and testing personnel, and improve the personnel\'s skill level and quality awareness. Implement a job responsibility system to allow each employee to clarify his or her own quality responsibilities and mission to ensure that the quality of the square and rectangular tubes produced is stable and reliable.

Quality management system control: Establish a complete quality management system, such as ISO 9001 quality management system certification, etc. Through the establishment and implementation of the system, the entire production process of square rectangular pipes is supervised and managed to ensure the consistency and traceability of product quality.

Supplier management: Strengthen the management of suppliers and select qualified and reputable raw material suppliers. Conduct regular evaluations and audits on suppliers to ensure that the quality and delivery time of raw materials meet requirements, and to ensure the quality of square and rectangular pipes from the source. Hunan Standard Steel Co., Ltd is a professional supplier of square and rectangular tubes.

Logistics and warehousing control: Reasonably arrange and manage the transportation and warehousing of square tube products to avoid product quality problems during transportation and warehousing. Monitor and maintain the storage and use environment of products to ensure stable product quality before use.

After-sales service control: Establish a sound after-sales service system to promptly handle and resolve quality issues reported by users. By collecting user feedback, we continuously improve product quality and service levels to enhance customer satisfaction.


Go here to learn more: Manufacturing process and application fields of square tubes

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Welding process of spiral welded steel pipe

Date : 2024-05-21

Basic concepts of spiral welded steel pipe:


Spiral welded steel pipe (SSAW) is a steel pipe made from steel plate or strip steel, rolled into a tube shape, and then continuously welded. It is widely used in petroleum, natural gas, chemical industry, heating, water transportation and other industries. It is characterized by high production efficiency, stable quality and low cost, so it is very popular.

Preparation work before welding of spiral welded steel pipe:

To ensure welding quality, we must first make preparations before welding, which mainly include the following:
1. Steel pipe cutting

Before cutting the steel pipe, it is necessary to ensure that its surface is clean and free of oil stains to avoid problems such as pores and inclusions. In addition, the cut must be straight and consistent in width to avoid deviations in subsequent welding.


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2. Bevel processing
Grooving is a very critical step in welding. The geometric size and shape of the welded groove will directly affect the quality and overall strength of the weld. Therefore, it must be processed according to the requirements to ensure that the groove size and shape meet the requirements.

3. Surface cleaning treatment

Before welding, the surface of the steel pipe must be cleaned to remove oil, rust and other impurities to ensure welding quality and subsequent quality inspection.


Welding parameter selection of spiral welded steel pipe:


The selection of welding parameters for spiral welded steel pipes is the key to determining the quality and output of the weld, mainly involving current, voltage, speed, etc. The best welding parameters should be selected according to the material type, thickness, cross-sectional shape, welding environment and other conditions.

Precautions for welding of spiral welded steel pipes:


In the actual operation of spiral welded steel pipes, the following matters should also be paid attention to:

1. Bevel distance
The groove distance should be kept as close as possible to the weld, which can minimize the heat-affected zone and reduce welding distortion.

2. Bevel position
Try to place the groove as low as possible to avoid sparks from splashing onto the groove during the welding process, causing quality problems.

3. Welding speed
The welding speed of spiral welded steel pipes should be moderate. If welding is too fast, the weld will be weak, and if welding is too slow, the weld will be insufficiently fused and of poor quality.

4. Welding form
There are two welding forms of spiral welded steel pipes, one is internal welding and the other is external welding. Internal welding is mainly used in water pipes, air pipes, hot water pipes and other fields; external welding is used in large-diameter gas pipelines, with the advantages of high production efficiency and stable quality.

Summarize:

The welding process of spiral welded steel pipes is a multi-faceted technology that requires operators to have sensitivity and expertise in every detail. Through the introduction of this article, readers can better understand the welding technology and precautions of spiral welded steel pipes, and improve the quality and efficiency of steel pipe welding.


Go here to learn more: Seamless vs Welded pipe

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Characteristics and uses of precision seamless tubes

Date : 2024-05-21

What is precision seamless tube?


Precision seamless tubes refer to seamless tubes & tubing with relatively high precision requirements, good surface finish, uniform pipe wall thickness, and precise dimensions. Its manufacturing process is complex and requires high precision processing technology and production equipment. It usually requires the use of cold drawing, cold crushing and other processing technologies, and the production cost is high.

Features and advantages of precision seamless tubes:

1. High precision: The precision of precision seamless tubes is very high. Its dimensional accuracy and shape accuracy can reach a very high level, and can meet various high-precision machining and assembly requirements.

2. High finish: The surface finish of precision seamless tubes is very high, and the surface roughness can reach Ra0.2~0.4, which can achieve a mirror polishing effect, making the surface quality of the product even better.


 precision seamless tubes


3. High strength: Precision seamless tubes have very high strength, with high tensile strength, yield strength, elongation and area shrinkage, and can withstand various high-intensity working loads.

4. Long life: Precision seamless tubes have good corrosion resistance and wear resistance, and can be used for a long time in harsh working environments, thereby increasing the service life of the entire product.

5. Good interchangeability: The precision seamless tube has very high dimensional accuracy and shape accuracy, and can be interchanged with other parts, thereby reducing the time and cost of repair and replacement.

Applications and uses of precision seamless tubes:

Precision seamless tubes are widely used in various fields. The following are several main uses:

1. Machinery manufacturing: Precision seamless tubes are widely used in the field of machinery manufacturing, such as the manufacturing of machine tools, hydraulic cylinders, bearings, gears and other mechanical components. Due to its high precision and high finish, it can improve the performance and accuracy of mechanical equipment.

2. Automobile manufacturing: In automobile manufacturing, precision seamless tubes are widely used in key parts of automobiles such as engines, chassis, and suspension systems. Due to its high strength and corrosion resistance, it can improve the reliability and safety of automobiles.

3. Petrochemical industry: In the petrochemical industry, due to the harsh working environment, materials with good corrosion resistance and high temperature resistance need to be used. Precision seamless tubes are widely used in key parts such as petrochemical pipelines, storage tanks and reactors due to their high strength, high corrosion resistance and high temperature performance.

4. Electric power industry: In the electric power industry, precision seamless tubes are widely used in the manufacturing of large equipment such as boilers, steam turbines, hydraulic turbines and generators. Due to its high strength and high precision, it can ensure the stability and reliability of power equipment.

5. Aerospace: In the field of aerospace, precision seamless tubes are widely used in key parts such as fuselages, wings, and landing gears. Due to its high strength, high corrosion resistance and high precision, it can ensure the safety and reliability of aerospace vehicles.

In short, precision seamless tubes, as a high-quality material, are widely used because of their characteristics such as high precision, high smoothness, high strength and long life. In fields such as machinery manufacturing, automobile manufacturing, petrochemical industry, electric power industry, and aerospace, precision seamless tubes play an irreplaceable role and provide important guarantees for the development of all walks of life.

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Comparison between Seamless pipe and ERW pipe

Date : 2024-06-07

The main differences between seamless pipes (SMLS) and ERW pipes are as follows:


1. Appearance
The outer surface defects of the blanks used in seamless steel pipes cannot be eliminated by the hot rolling process. The defects can only be polished after the finished product is completed; the spiral path left after piercing can only be partially eliminated in the process of reducing the wall. 

ERW steel pipe uses hot-rolled coils as raw materials. The surface quality of the coils is the surface quality of ERW steel pipes. The surface quality of hot-rolled coils is easy to control and high in quality. Therefore, the surface quality of ERW steel pipes is much better than that of seamless steel pipes. 

2. Outer diameter tolerance
ERW steel pipe: It is cold-formed, and the sizing is completed by 0.6% reduction. The process temperature is basically constant at room temperature, so the outer diameter control is accurate and the fluctuation range is small, which is helpful to eliminate black leather buckles;

Seamless steel pipe: hot-rolled forming process is adopted, and its sizing is completed at about 8000C. The raw material composition, cooling condition and cooling state of the roll of the steel pipe have a great influence on its outer diameter, so it is difficult to accurately control the outer diameter and fluctuate The range is larger.


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3. Wall thickness tolerance
ERW steel pipe: using hot-rolled coil as raw material, modern hot-rolling thickness tolerance can be controlled within 0.05mm, while seamless steel pipe is produced by round steel perforation method, the wall thickness deviation is large, and the subsequent hot rolling can partially eliminate the wall Thickness unevenness, but the most advanced unit can only be controlled within +5~10%t, which corresponds to 8.94mm thick steel pipe.

Seamless steel pipe: The limit of wall thickness control accuracy is 0.9mm.

4. Ovality
ERW steel pipe: adopts cold bending forming, so the outer diameter control is accurate and the fluctuation range is small.
Seamless steel pipe: Hot-rolled forming process is adopted. The raw material composition of the steel pipe, the cooling condition and the cooling state of the roll have a great influence on its outer diameter, so it is difficult to accurately control the outer diameter and has a large fluctuation range.

5. Tensile test
The tensile properties of seamless steel pipes and ERW steel pipes conform to API standards, but the strength of seamless steel pipes is generally at the upper limit and the plasticity is at the lower limit. In comparison, the strength index of ERW steel pipes is in the best state, and the plasticity index is 33.3% higher than the standard. The reason is that the performance of hot-rolled coils, the raw material of ERW steel pipes, is guaranteed by means of microalloying smelting, out-of-furnace refining, and controlled cold and controlled rolling; seamless steel pipes mainly rely on means to increase carbon content, and it is difficult to ensure strength and plasticity. Reasonable match.

6. Hardness
The raw material of ERW steel pipe, a hot-rolled coil, has a very high precision of controlled cold and controlled rolling during the rolling process, which can ensure the uniform performance of all parts of the coil.

7. Grain body
The hot-rolled strip, the raw material of ERW steel pipe, uses a wide and thick continuous casting billet, with a thicker fine-grained surface solidification layer, no columnar crystal regions, shrinkage holes and looseness, small composition deviation, and compact structure; in the subsequent rolling process In the middle, the application of controlled cold and controlled rolling technology further ensures the grain size of raw materials.

8. Anti-collapse test
ERW steel pipe is due to the characteristics of its raw materials and pipe-making process. Its wall thickness uniformity and ellipticity are far better than seamless steel pipes, which is the main reason why the collapse resistance performance is higher than that of seamless steel pipes.

9. Impact test
Since the impact toughness of the base material of ERW steel pipe is several times that of seamless steel pipe, the impact toughness of the weld is the key of ERW steel pipe. By controlling the impurity content of raw materials, the height and direction of slitting burrs, the shape of the forming edge, the welding angle, and the welding speed , Heating power and frequency, welding extrusion volume, intermediate frequency withdrawal temperature and depth, air-cooling section length and other process parameters ensure that the impact energy of the weld reaches more than 60% of the base metal. If further optimized, the weld impact energy can be close to that of the base metal. Material, so as to achieve seamless performance.

10. Blasting test
The blasting test performance of ERW steel pipe is much higher than the standard requirement, mainly due to the high uniformity of wall thickness and uniform outer diameter of ERW steel pipe.

11. Straightness

The ERW steel pipe is cold-worked, and it has online straightening in the reduced diameter state, and the infinite multiple ruler is added, so the straightness is better; the seamless steel pipe is formed in the plastic state, plus the single ruler (continuous rolling is 3 ~4 times the ruler) The straightness of the pipe end is relatively difficult to control.


12. Amount of steel used for casing per 10,000 meters of footage
The wall thickness of ERW steel pipes is uniform and its wall thickness tolerance is negligible, while the control accuracy limit of the wall thickness difference of seamless steel pipes is ±5%t, which is generally controlled at ±5~10%t. To ensure that the minimum wall thickness can meet the standard requirements and performance, the only solution is to increase the wall thickness appropriately. Therefore, for casing of the same specifications and weight, ERW steel pipes are 5 to 10% longer than seamless steel pipes, or even more, which reduces the steel consumption of casing per 10,000 meters of footage by 5 to 10%. Even at the same price, ERW steel pipes virtually save users 5 to 10% of purchasing costs.


Tips: ASTM A53 covers seamless and welded steel pipe with nominal wall thickness. The surface condition is usually black and hot-dipped galvanized. ASTM A53 is produced mainly for pressure and mechanical applications, and is also used for transport of steam, water, gas line pipes.


Go here to learn more: Classification and application of welded steel pipe

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How to prevent gas leakage in gas pipeline connections?

Date : 2024-06-07

How to prevent gas leakage in gas pipeline connections?

Common pipe connection methods:
Gas pipeline connection methods generally include wire connection, flange connection and socket connection. Among them, wire connection is the most common and the most prone to air leakage.

Reasons for gas pipe joint leakage:

Reasons for gas pipe joint leakage may include loose pipe joints, aging seals, poor pipe quality, etc. If joint leakage is not dealt with in time, it will pose a threat to people\'s lives and property.


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Common types of gas pipe joints:

In the installation and use of gas pipelines, it is crucial to ensure that there are no air leaks. Choosing the right connector and the correct connection method are key steps in achieving this goal. Here are some common types of gas line fittings:
1. Flange type interface: This type of joint uses flanges and bolts to connect pipelines. Because of its excellent sealing performance, it is usually used in large pipelines and high-pressure systems.

2. Threaded interface: The threaded interface tightly connects the joint to the pipe through matching threads to achieve a sealing effect. Unlike flange-type interfaces, it is more suitable for applications in small pipelines and low-pressure systems.

3. Compression-type joint: This type of joint uses compression sleeves and washers to fix the pipe on the joint, and is compressed by nuts to achieve a sealing effect. It is mainly suitable for small and medium-sized pipelines and medium and low pressure systems (boiler tube).

4. Welded interface: The welded interface directly connects the pipes together through welding technology to form a strong and leak-proof connection. This kind of joint is usually used in pipeline systems that require long-term stable operation and high sealing.

No matter which joint is used, it is necessary to choose high-quality joints and sealing materials, and strictly follow safe operating procedures for installation. In addition, sealants or gaskets can be added appropriately at pipe connections to enhance their sealing performance.

Commonly used leakage prevention measures for gas pipeline joints:

1. Leak-proof wire connection: Before installing the pipeline, you can use high-temperature and corrosion-resistant sealing materials to ensure that the sealing links will not be damaged or aged. At the same time, when making wire connections, strengthen the strength to ensure fastening. .

2. Flange connection is leak-proof: Flange connection is suitable for pipe brackets, elbows, joints and other parts. This connection method requires the selection of high-quality flanges and sealing gaskets to ensure a tight and leak-free connection.

3. Socket-type connection is leak-proof: Socket-type connection is to insert a pipe into a section of pipe, and use sealing materials to ensure sealing. It is suitable for pressure maintenance, pressure reduction, etc., and needs to be installed in strict accordance with the installation requirements.

Routine maintenance of gas pipelines:
In addition to choosing appropriate pipe connection methods and taking leakage prevention measures, you also need to pay attention to the following points in daily use:
1. Ensure compliance with pipeline usage regulations and operating specifications.
2. Regularly check the pipe connections for leaks and looseness, and repair and tighten them in time.
3. Environmentally friendly pipelines must be installed and tested using professional equipment.
4. Pipeline inspection and repairs are best done by professionals.
5. It is forbidden to modify the pipelines at will, and strictly control the gas usage.

Summarize:

Gas pipe joint leakage accidents often bring great safety risks to our production and life. Choosing the appropriate gas pipeline connection method and taking leakage prevention measures are key. At the same time, we also need to pay attention to pipeline maintenance and safe use in daily use. Hope this article can be helpful to you.


Go here to learn more: What are the common pipe fittings and pipe connection methods?

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