What pipes need pickling, degreasing and passivation?

Mainly for steel pipes, corrosion reaction is easy to occur, and there are certain hidden dangers to equipment damage after corrosion. The corrosion resistance of steel can be greatly improved after removing all kinds of dirt such as oil stain, rust, scale and solder joint.

If there is dirt on the surface of stainless steel pipeline, it should be cleaned mechanically and then degreased. The presence of surface grease will affect the quality of pickling passivation. Therefore, degreasing cannot be omitted, and alkali solution, emulsifier, organic solvent and steam can be used.

Passivation is the last working procedure and key step of chemical cleaning, and its purpose is to prevent material corrosion. For example, after pickling, washing and rinsing, the metal surface of the boiler is very clean, very lively and easy to corrode, so it must be passivated immediately to form a protective film on the cleaned metal surface to slow down corrosion.

Extended data

The pickling passivation of stainless steel originated in Norway, and it was not studied until 1992 in China. Now it is widely used in shipbuilding and metallurgical industries.

There are many types of pipeline corrosion, such as oxygen absorption corrosion, bacterial corrosion and sulfur dioxide corrosion. Delaying pipeline corrosion, that is, pipeline anti-corrosion, is an important link in pipeline maintenance and one of the key points to promote the safe production of pipeline transportation industry.

Conventional pipeline anticorrosion mainly includes the following methods.

(1) Reasonable material selection: different kinds of metal or nonmetal materials are selected according to different conveying media and environmental conditions;

(2) Electrode protection: Cathodic protection refers to the external DC power supply, that is, the pipeline metal originally used as the anode is changed into a protected cathode, or the metal with relatively more chemical activity can be attached to the pipeline to form a galvanic cell, at this time, the more active metal is corroded, and at the same time, the pipeline itself and the anode are protected; Anode protection is to connect the protected equipment to the anode of an external power supply to form a passivation film on the metal surface to protect the metal equipment;

(4) Medium treatment: including removing corrosive components in the medium or adjusting its PH value;

(5) Add anti-corrosion coating (such as paint) on the metal surface to isolate the steel pipeline from oxygen in the air and achieve protection.

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