Welded Pipe Executive Standard Classification
In the Chinese GB/T system, welded steel pipe is classified by its executive standard, and each standard defines the service scope, representative materials, and test requirements. Understanding this classification prevents the common mistake of substituting one welded pipe family for another in service that demands a different standard.
1. Low-Pressure Fluid Standards
GB/T 3091 (Galvanized welded steel pipe for low-pressure fluid transportation): mainly transports water, gas, air, oil, heating hot water, and steam at general lower pressures. Representative material: Q235A grade steel.
GB/T 3092 (Galvanized welded steel pipe for low-pressure fluid transportation): covers the same low-pressure fluid duties with Q235A as the representative material.
GB/T 14980 (Large-diameter electric welded steel pipe for low-pressure fluid transportation): for water, sewage, gas, air, and heating steam at low pressure, also with Q235A grade steel.
2. Mining and Special Duty Standards
GB/T 14291 (Welded steel pipe for mining fluid transportation): straight seam welded steel pipe for mine air pressure, drainage, and shaft gas discharge. Representative materials: Q235A and Q235B grade steel.
3. Stainless Welded Pipe Standards
GB/T 12770 (Stainless steel welded pipes for mechanical structures): used in machinery, automobiles, bicycles, furniture, and hotel and restaurant decoration as mechanical and structural parts. Representative materials include 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, and 0Cr18Ni11Nb.
GB/T 12771 (Stainless steel welded pipes for fluid transportation): for low-pressure corrosive media. Representative materials: 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, and 00Cr17Ni14Mo2.
| Executive Standard | Service Scope | Representative Material |
|---|---|---|
| GB/T 3091 | Low-pressure fluid (galvanized) | Q235A |
| GB/T 3092 | Low-pressure fluid (galvanized) | Q235A |
| GB/T 14291 | Mining fluid transport | Q235A / Q235B |
| GB/T 14980 | Large-diameter low-pressure fluid | Q235A |
| GB/T 12770 | Stainless mechanical structures | 0Cr13, 1Cr18Ni9, 0Cr18Ni11Nb |
| GB/T 12771 | Stainless fluid transport | 0Cr19Ni9, 00Cr19Ni11, 00Cr17Ni14Mo2 |
FAQs
What does an executive standard mean for welded pipe?
It is the governing specification that fixes the service scope, material grades, dimensions, and tests the pipe must meet - the legal basis for acceptance.
Which standard covers galvanized water pipe?
GB/T 3091 (and its predecessor GB/T 3092) covers galvanized welded pipe for low-pressure water, gas, and heating service.
What is the difference between GB/T 12770 and GB/T 12771?
GB/T 12770 is for stainless welded pipe used in mechanical structures; GB/T 12771 is for stainless welded pipe transporting low-pressure corrosive fluids.
Can mining welded pipe be used for general water service?
Mechanically it often can, but the executive standard, tests, and documentation differ; always select the standard that matches the actual service.
Are these GB/T standards still current?
Several of these editions have been superseded - for example, GB/T 3091 was updated (2015 edition is current) - so verify the latest edition before ordering.
What tests apply to low-pressure welded pipe?
Typically hydrostatic testing, flattening and bending tests, dimensional checks, and surface quality inspection as defined by the applicable GB/T standard.
