What are the acceptance standards for stainless steel seamless pipes at construction sites

The acceptance standards for stainless steel seamless pipes at construction sites mainly include the following aspects:

Quality certificates

Stainless steel seamless pipes should have quality certificates, which should include information such as the name of the manufacturing factory, product specifications, quantity, production date, applicable standards, mechanical properties, chemical composition, etc., and should be consistent with the actual goods.

The product should also have a certificate of conformity, proving that this batch of stainless steel seamless pipes has passed the internal quality inspection and meets the requirements of relevant standards.

Appearance quality

The surface of the stainless steel seamless pipe should be smooth, and there should be no cracks, folds, bends, delamination, scars, etc. If there are minor defects, their depth should not exceed the negative deviation of the pipe wall thickness and should not exceed 0.5mm.

The cut end of the pipe should be flat, without burrs, flying edges, etc., and the end face of the cut should be perpendicular to the axis of the pipe, with an inclination angle not exceeding the specified value.

Dimensional deviation

Outer diameter deviation: According to GB/T 14976-2012 "Fluid Transport Stainless Steel Seamless Pipes", when the outer diameter is less than or equal to 50mm, the allowable deviation is ±0.3mm; when the outer diameter is greater than 50mm, the allowable deviation is ±0.6%.

Wall thickness deviation: When the wall thickness is less than or equal to 3mm, the allowable deviation is ±0.15mm; when the wall thickness is greater than 3mm, the allowable deviation is ±5%.

Length deviation: The allowable deviation of the fixed-length length of the pipe is ±5mm. If there are special requirements in the contract, they shall be executed in accordance with the contract provisions. Mechanical properties

The mechanical properties of stainless steel seamless pipes should comply with the provisions of relevant standards such as GB/T 14976, mainly including yield strength, tensile strength, elongation after fracture, etc. For example, the yield strength of 304 stainless steel seamless pipes should be no less than 205 MPa, the tensile strength should be no less than 520 MPa, and the elongation after fracture should be no less than 40%.

If necessary, hardness tests, impact tests, etc. can be conducted according to engineering requirements to further verify the mechanical properties of the pipes. Chemical composition

The chemical composition of stainless steel seamless pipes should comply with the requirements of corresponding national standards. For example, the main chemical composition requirements for 304 stainless steel are: carbon content not exceeding 0.08%, chromium content ranging from 18.00% to 20.00%, nickel content ranging from 8.00% to 11.00%, etc.

The chemical composition of the pipes can generally be verified through chemical analysis reports. If necessary, on-site sampling inspections can be conducted using methods such as spectroscopy analysis.

Corrosion resistance test

For construction sites with special corrosion resistance requirements, intergranular corrosion tests, pitting corrosion tests, etc. can be carried out according to engineering needs to test the corrosion resistance of stainless steel seamless pipes.

The test methods for intergranular corrosion are carried out in accordance with relevant standards such as GB/T 4334. After the test, the pipes should have no tendency for intergranular corrosion and meet the corresponding quality requirements.

These are the main acceptance standards for stainless steel seamless pipes in construction sites. During actual acceptance, it should be carried out in accordance with engineering design requirements and relevant standard specifications to ensure that the quality of the pipes meets the requirements for engineering use.