What is a Welded Steel Pipe?
Welded steel pipe is referred to as welded pipe. It is a steel pipe made by welding steel or steel strip after curling and forming by a unit and a die. The production process of welded steel pipe is simple, the production efficiency is high, the varieties and specifications are many, and the equipment investment is low, but the general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip steel continuous rolling production and the progress of welding and inspection technology, the quality of welds has been continuously improved, the varieties and specifications of welded steel pipes have increased day by day, and they have replaced seamless steel pipes in more and more fields, especially in heat exchange spare pipes, decorative pipes, medium and low pressure fluid pipes, etc.
Straight seam welded pipe has a simple production process, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It can produce welded pipes with larger diameters with narrower billets, and can also produce welded pipes with different diameters with billets of the same width. However, compared with straight seam pipes of the same length, the weld length increases by 30~100%, and the production speed is lower.
Generally speaking, the diameter of the pipe can be divided into outer diameter, inner diameter and nominal diameter. The outer diameter of the spiral steel pipe is represented by the letter D, followed by the outer diameter size and wall thickness, such as a seamless steel pipe with an outer diameter of 108.
National standards for welded steel pipes
1. GB/T3091-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam and other generally low-pressure fluids and other pipes. Its representative material is Q235A grade steel.
2. GB/T3092-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam and other generally low-pressure fluids and other pipes. Its representative material is: Q235A grade steel.
3. GB/T14291-1992 (welded steel pipe for fluid transportation in mines). It is mainly used for straight seam welded steel pipes for mine compressed air, drainage, and axial gas discharge. Its representative material is Q235A and B grade steel. GB/T14980-1994 (Large diameter electric welded steel pipe for low-pressure fluid transportation). Mainly used for conveying low-pressure fluids such as water, sewage, gas, air, heating steam and other purposes. Its representative material is Q235A grade steel.
4. GB/T12770-1991 (Stainless steel welded steel pipe for mechanical structure). Mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.
Welded steel pipe is a kind of pipe product widely used in the modern construction industry. However, the quality standards it needs to meet are different according to the environment and geographical location in which it is used. What are the standards for welded steel pipes used in the construction industry? The implementation standards of welded steel pipes in the market:
GB/T3091-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam and other general low-pressure fluids and other pipes. Its representative material is Q235A grade steel.
GB/T3092-1993 (galvanized welded steel pipe for low-pressure fluid transportation). It is mainly used for conveying water, gas, air, oil, heating hot water or steam and other general low-pressure fluids and other pipes. Its representative material is: Q235A grade steel.
GB/T14291-1992 (welded steel pipe for fluid transportation in mines). It is mainly used for straight seam welded steel pipes for mine air compression, drainage, and axial gas discharge. Its representative materials are Q235A and B grade steel.
GB/T14980-1994 (Large diameter electric welded steel pipe for low pressure fluid transportation). Mainly used for conveying low pressure fluids such as water, sewage, gas, air, heating steam and other purposes. Its representative material is Q235A grade steel.
GB/T12770-1991 (Stainless steel welded steel pipe for mechanical structure). Mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.
GB/T12771-1991 (Stainless steel welded steel pipe for fluid transportation). Mainly used for conveying low pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.
Manufacturing Standards for Welded Steel Pipes
Various international and national standards regulate the production of welded steel pipes to ensure quality and safety. Some key standards include:
1. API 5L (American Petroleum Institute)
Used for oil and gas transportation pipelines.
Covers both seamless and welded pipes.
2. ASTM Standards (American Society for Testing and Materials)
ASTM A53: Standard for welded and seamless black and galvanized steel pipes.
ASTM A252: Standard for piling pipes.
ASTM A500: Standard for structural steel tubing.
3. EN & ISO Standards (European and International)
EN 10219: Structural hollow sections of non-alloy and fine grain steels.
ISO 3183: International standard for petroleum and natural gas industries.
By following these standards, manufacturers ensure that welded steel pipes meet safety, durability, and performance requirements.
What are the implementation standards for stainless steel welded pipes?
1. GB/T 12771-2024
This is the latest implementation standard for stainless steel welded pipes, which specifies the classification, specifications, material requirements, manufacturing process and quality control requirements of stainless steel welded pipes. Stainless steel welded pipes are divided into four types: austenitic stainless steel welded pipes, ferritic stainless steel welded pipes, austenitic-ferritic stainless steel welded pipes, and high-alloy stainless steel welded pipes. The standard also specifies in detail the test methods for stainless steel welded pipes, including surface quality, mechanical properties, chemical composition, non-destructive testing, pressure testing, etc.
2. GB/T 12771-2008
Although GB/T 12771-2024 has replaced this standard, GB/T 12771-2008 was widely used before to guide the production and quality control of stainless steel welded pipes for fluid transportation. This standard mainly stipulates the technical requirements, test methods, inspection rules, packaging, marking and quality certificates of stainless steel welded pipes for fluid transportation. It is mainly used to transport low-pressure corrosive media. Representative materials include 06Cr19Ni10, 022Cr19Ni10, 06Cr19Ni110Ti, 00Cr17, 0Cr18Ni11Nb, 06Cr17Ni12Mo2, etc.
3. GB/T 12770-2012
This standard applies to stainless steel welded steel pipes for mechanical structures, mainly used for mechanical parts and structural parts such as machinery, automobiles, bicycles, furniture, and hotel decoration. Its representative materials include 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.
In addition, there are other implementation standards related to stainless steel welded pipes, such as GB/T 14976-2012 "Stainless steel seamless pipes for fluid transportation" and GB/T 20833-2008 "Austenite-ferrite duplex stainless steel seamless pipes". These standards put forward different technical requirements and quality control measures for different types of steel pipes to ensure the performance and safety and reliability of steel pipes in various use environments.
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