What are the inspection standards for anti-corrosion steel pipes

First, what are the inspection procedures for anti-corrosion steel pipes?

Anti-corrosion steel pipes are inspected in batches of 20.

1. Thickness inspection of anti-corrosion steel pipes: The thickness of the anti-corrosion layer is measured according to the specified thickness for the anti-corrosion grade, using an anti-corrosion layer thickness gauge. One pipe is randomly selected from every 20 pipes, and three cross-sections at certain intervals are measured on each pipe. Four points are measured at the top, bottom, left, and right of each cross-section. If the thinnest point is below the specified thickness, it is considered unqualified. Two more pipes are randomly selected; if one of them is still unqualified, all are considered unqualified.

2. Pinhole inspection of anti-corrosion steel pipes: A spark leak detector must be used for testing. The detection voltage is 2000V for ordinary grade, 3000V for reinforced grade, and 5000V for extra-reinforced grade. No sparks are considered acceptable. One pipe is randomly selected from every 20 pipes, and the measurement is taken from one end of the pipe to the other. If any pipe fails the test, two more pipes will be randomly selected for inspection. If one of these pipes also fails, all pipes are considered unqualified.

3. Adhesion test of anti-corrosion steel pipes: After the anti-corrosion layer of the steel pipe has cured (generally requiring 7 days), make a tongue-shaped incision with a knife and forcefully tear off the anti-corrosion layer at the cut. If it is difficult to tear off, and the steel pipe surface at the damaged area is still covered by the paint film without exposing the iron, then it is considered qualified. Following the above method, randomly select one pipe out of every 20 pipes and apply one spot of paint to each pipe. If any pipe fails the test, two more pipes will be randomly selected for inspection. If one of these pipes also fails, all pipes are considered unqualified. Unqualified pipes should be removed and re-coated.

Second, what are the anti-corrosion standards for steel pipes?

1. FBE epoxy powder coating follows SY/T0315—2005 "Technical Specification for Single-Layer Fusion-Bonded Epoxy Powder External Coating of Steel Pipelines".

2. 2PE/3PE anti-corrosion follows GB/T23257-2009 "Technical Standard for Polyethylene External Coating of Buried Steel Pipelines".

3. Rust removal standards for the anti-corrosion surface of anti-corrosion steel pipes: The outer surface of the anti-corrosion steel pipe shall be sandblasted to achieve Sa2 1/2 grade according to GB/T8923-2008, and the anchor pattern depth on the surface of the anti-corrosion steel pipe shall be 40-100μm.