Operation steps for pickling 304 stainless steel pipes.
1. Pipe ready
2. Chemical degreasing
(1) The chemical oil removal adopts the immersion method in the tank, and the oil removal tank is made of steel plate, with PVC or polyethylene laid on the inner wall.
(2) Chemical degreasing treatment uses 12-15% nitric acid (by volume) at a temperature of 40 ℃ to 60 ℃ for 2-4 hours.
(3) When soaking 304 stainless steel pipes in the tank, attention should be paid to their placement to avoid leaving air inside the pipes.
(4) During the soaking process, the tube should be moved up and down or flipped, and the internal solution should be constantly replaced to improve the effect. If necessary, remove the tube, rinse with water and gas, and then soak.
(5) Chemical degreasing until the surface of the pipe fittings is completely wet.
3. Hot water flushing
(1) Remove the 304 stainless steel sanitary pipe after oil removal from the oil removal tank and soak it in a hot water tank at around 40 ℃~60 ℃ for rinsing for 5-20 minutes.
(2) The hot water tank is made of steel plate, and the inner wall is covered with polyvinyl chloride or polyethylene.
(3) O teor de íons de cloreto na água é inferior a 25ppm.
4. Enxágue com água.
(1) Usar água de pressão (pressão P ≥ 0, 1Mpa) para enxaguar os canos que foram lavados com água.
(2) O teor de íons de cloreto na água é inferior a 25ppm.
5. Passivação
(1) Selecione a fórmula da solução de passivação e o tempo de imersão de acordo com as tabelas 2 and 3.
(2) Produz placas de aço com sulcos de passivação com plástico resistente a ácidos nas paredes internas.
(3) Ao mergulhar no tanque, preste atenção ao posicionamento para evitar ar dentro do tubo.
(4) During the soaking process, os encaixes do tubo devem ser movidos para cima e para baixo ou virados, and the internal solution should be constantly replaced to improve the effect. If necessary, os tubos devem ser removidos, washed with water and gas, and then soaked.
6. Drying
After passivating the 304 stainless steel sanitary pipe, dry it with clean compressed air or nitrogen, and there must be sufficient time (at least 2 hours) for natural passivation in the air.
7. Inspection
After passivation of 304 stainless steel sanitary pipes, self inspection and mutual inspection should be conducted, and then submitted to quality inspection personnel for acceptance as required.
8. Protection
(1) Pipe fittings that require painting on the outer surface shall be painted according to the painting requirements.
(2) The pipes that pass the inspection shall be sealed with plastic plugs, wrapped with three proof cloth for protection, and marked.