The stainless steel plates purchased for the manufacture of storage tank must be 304 (0Cr18Ni9), and plates with insufficient chromium and nickel will not be used, and the machined surface must not have defects such as interlayer and heavy skin.
Manufacture process of the inner tank head:
1. The stainless steel plates to be used shall be re-inspected upon entering the factory according to the requirements.
2. The process drawing for the inner tank head shall be prepared and reconfirmed.
3. The size of the head plates shall be according to the requirements of the factory for the dishing work.
4. Head plates scribing, blanking, plasma cutting, bevel processing (blunt edge 4mm, 30-degree bevel), grouped back-side hand-soldering (welding rod Ao 107).
5. Submerged arc welding, welding wire H0Cr21Ni10, soldering flux 260. The back is protected by a longitudinal flux pad, the back is carbon arc air gouged and ground to a metallic luster with an angle grinding wheel, and the back is welded by submerged arc welding.
6. Dishing process. Spin the tank head plate according to the requirements of the drawing, and leveling the head for flanging according to the requirements.
7. After the dishing process, 100% radiographic inspection shall be performed on the welds, and the grade II is required.
8. Scribe the right tank head and make holes according to the piping details (plasma cutting), the opening position should have a distance of not less than 100mm to welding seams, grind the groove with the grinding wheel and grinding head, place and and spot weld the transition nozzle, then perform full penetration welding on both sides, with welding wire H0Cr21Ni10. 100% dye penetration inspection on the weld shall be carried out after welding.
9. The left tank head is the the piece closing the inner tank. Group and spot weld the left head and the liner. Intermittently weld the liner and the tank head side with argon arc welding, 100% welded and 80% unwelded. Apply argon arc welding and self-fusion sealing to the liner and the head groove.
10. The left and right heads are degreased and ready to be paired.
11. Strict discipline during the process shall be enforced.