What are the matters that need attention in seamless steel pipe pickling?
Seamless steel pipe pickling is an important process to remove oxides, rust and other impurities on the surface of the steel pipe to improve its surface quality and corrosion resistance. In the pickling process, it is necessary to pay attention to the following aspects:
1. Preliminary preparation
Wear labor protection supplies: Before pickling seamless steel pipes, the staff must wear labor protection supplies, such as anti-acid gloves, goggles, protective clothing, etc., to prevent the acid from splashing onto the body and causing injury.
Check the working environment: the working environment of the site is inspected in detail, mainly to check whether the sling of the seamless steel pipe is intact, and the operation can be carried out after confirmation. At the same time, ensure that the pickling area is well ventilated to reduce the accumulation of harmful gases.
2. pickling operation
Choose the right pickling agent: commonly used pickling agent are sulfuric acid, hydrochloric acid and phosphoric acid. The selection of suitable pickling agent needs to take into account factors such as steel pipe material, surface contamination degree and requirements. For example, hydrochloric acid pickling has the ability to remove rust and oxides, and the operation is relatively safe and easy to control the concentration.
Control the concentration and temperature of pickling solution: The concentration and temperature of pickling solution will directly affect the pickling effect. In general, the concentration of hydrochloric acid is between 5% and 15%, and the concentration of sulfuric acid is between 1% and 10%. The temperature also needs to be within the appropriate range, avoiding too high or too low. The high temperature may cause the acid to volatilize too fast and affect the pickling effect. Too low a temperature may make the pickling reaction too slow.
Determine the pickling time: The pickling time needs to be determined according to the material, thickness and surface contamination of the steel pipe. Generally speaking, the pickling time should not be too long to avoid excessive corrosion of the steel pipe. The time is usually controlled between 5 and 15 minutes, and the specific time can be adjusted according to the actual situation.
Ensure uniform coverage of acid: In the pickling process, the seamless steel pipe needs to be frequently vibrated to ensure that the acid can evenly cover the surface of the steel pipe. At the same time, when going down the pipe to the acid tank, the seamless steel pipe should be tilted to prevent hydrochloric acid from injuring people.
Control the weight of steel pipe: For pickling seamless steel pipe, its weight should be controlled within a certain range, usually between 2 and 5 tons, to ensure the consistency and safety of the pickling effect.
3. Follow-up treatment
Full cleaning: After pickling, the seamless steel pipe needs to be fully cleaned to remove the residual acid and impurities. After cleaning, it is also necessary to blow dry the steel pipe to avoid secondary corrosion caused by residual water.
Passivation treatment: In order to improve the corrosion resistance of seamless steel pipes, passivation treatment can be carried out after pickling. Passivation is achieved by forming a dense oxide film on the surface of the steel pipe, and the passivation agent usually used is chromic acid solution.
4. safety protection and environmental protection
Strict compliance with safety operating procedures: In the entire pickling process, it is necessary to strictly comply with safety operating procedures to ensure the personal safety of the staff.
Regular inspection and maintenance of pickling equipment: to prevent accidents caused by equipment failure.
Environmental protection treatment: Chemical waste such as acid lotion should be treated and recycled in accordance with environmental protection requirements to avoid pollution to the environment.
