Quality Inspection of Thick-Walled Steel Pipe Coils

The quality inspection of steel coil pipes shall comply with the following requirements in addition to executing Clause 4.2.1.

When the diameter of the coil pipe is greater than 600mm, two longitudinal seams are permitted, with a spacing between the seams greater than 300mm.

(2) The spacing between the two longitudinal seams should be greater than 100mm. The distance from the outer wall of the branch pipe to the longitudinal and circumferential seams should not be less than 50mm.

(3) The circumference deviation and ellipticity of the rolled tube shall comply with the specifications of the design documents or manufacturing standards.

(4) The end face of the coiled pipe should not deviate more than 1% of the outer diameter of the pipe from the centerline, and not more than 3mm. The flatness deviation should not exceed 1mm/m.

(5) During the rolling process, the surface of the sheet material should be protected from mechanical damage. Areas with severe scratches should be smoothed and transitioned smoothly. The depth of the smoothing should not exceed 10% of the board's thickness.

All seams on the coiled pipes must pass the penetration test. The appearance inspection of the seams should be conducted in accordance with the welding inspection regulations. After the steel pipe processing is complete, a leakage test should be carried out as per the specifications.

Inspection of Welding Materials for Thick-Walled Seamless Tubes

(1) The project team is to inspect the quality certificates of the welding materials used by the construction contractor, ensuring that the quality of welding rods and wires meets or exceeds the current national standards. They must also comply with the specifications of the welding process evaluation approved by the project team or the design. The project team inspectors must maintain accurate records.

(2) The design unit shall provide welding performance data for the new materials selected for the design.

(3) The flux coating of welding rods must not have any detachment or obvious cracks. Welding rods with a shelf life exceeding one year should undergo a welding process performance test, and only upon passing the test can they be used.

(4) The project team is required to inspect the storage facilities for welding materials at the construction site, as well as the drying and cleaning equipment, i.e., the secondary welding rod storage. These facilities should comply with the current national standard "Regulations for Welding Rod Quality Management" 3223. The construction contractor should establish a system for the storage, drying, cleaning, and distribution of welding materials. The project team must conduct inspections, confirm compliance, and maintain inspection records.