Take you to know the quality and welding essentials of stainless steel flexible waterproof casing
During the use of stainless steel flexible waterproof casing, we will encounter welding work. Do you know the essentials of stainless steel flexible waterproof casing welding? Here is a detailed introduction:
1. The overall dimension of the welding seam of flexible casing shall comply with the provisions of the drawings and process documents. The height of the weld shall not be lower than the surface of the base metal, and the weld and the base metal shall transition smoothly.
2. There shall be no crack, incomplete fusion, incomplete penetration, slag inclusion, crater, air hole and other defects on the weld of flexible waterproof casing and the surface of heat affected zone.
3. For welds that pass the appearance inspection, ultrasonic testing shall be carried out for the welds, and the qualification level is level II.
4. No surface defects are allowed on the weld surface of the weld bead of the flexible casing pipeline, the undercut depth is less than 0.5mm, and the length is less than or equal to 10 and less than 100mm of the total length of the weld.
5. The pipeline shall be horizontal and vertical, the verticality of the riser shall not exceed 15mm, the alignment misalignment shall be less than 1mm, and the elevation error shall be less than 20mm; Flange parallelism is less than 0.3mm.
6. Before the anti-corrosion pipe is laid in the trench, the electric spark leak detector shall be used to detect all the pipelines, the leak detection voltage is 2.5KV, and the inspection records shall be filled in.
7. Before backfilling the flexible waterproof casing pipe, the pressure test shall be carried out, and the concealed works record shall be filled in, which can be backfilled only after being confirmed by the construction unit.
8. The welded junction shall be smooth and flat to ensure that there are no unqualified places such as welding slag and pores;
9. Oil penetration inspection shall be carried out after the appearance inspection is qualified. Unqualified welds shall be removed and re welded, and the number of re welding shall not exceed three times.
10. After the appearance and oil penetration inspection of the weld are qualified, the weld nondestructive testing shall be carried out, and the sampling quantity shall meet the requirements of the design and relevant specifications.
Flexible waterproof casing is generally applicable to structures with vibration or strict waterproof requirements where the pipeline passes through the wall. After partial processing, the outer wall shall be painted with primer (primer includes Zhangdan or cold primer oil). The outer anti-corrosion is determined by the design. For the wall where the casing passes through the wall, in case of non concrete wall, the concrete wall shall be used. The concrete pouring range shall be 200mm larger than the wing ring diameter (D6), and the casing shall be poured into the wall. The thickness of the concrete wall where the pipe passes through shall not be less than 300mm, otherwise the wall shall be thickened on one side or both sides. The diameter * of the thickened part shall be 200mm larger than the wing ring diameter (D6). The material weight of casing is calculated according to the wall thickness L value of 300mm. If the wall thickness is greater than 300mm, it shall be calculated separately. The welding material of casing parts is made of A3 material and welded with T42.