Anticorrosive sandblasting and shot blasting construction of offshore platform

Surface treatment before coating of offshore platform

1. The method of surface derusting

In order of rust removal: first rust removal, second rust removal.

According to the process stage: rust removal in the workshop and overall rust removal.

According to the rust removal method: spray rust removal, power tool rust removal, pickling rust removal, etc.

Spray rust removal is a thorough, high-efficiency rust removal method that can realize automatic assembly line operation. Shot blasting, shot blasting, sand blasting and vacuum jetting are commonly used for spray rust removal.

2. Acceptance criteria for derusting steel surface

(1) In order to determine the degree of rust and the quality level, generally the various surface conditions of the steel and the quality level of rust removal are clearly compared with color photos.

(2) Surface treatment standard "Steel surface corrosion grade and derusting grade", ISO 8501 is widely used internationally, there are also Swedish standard SIS055900, national standard GB8923-88 and so on.

Rust grade of steel

Divided into four levels: A, B, C, and D. The specification uses photos to indicate the level of rust, arranged in order according to the degree of rust. A is lighter and D is the most rusty.

钢材的锈蚀等级

3. Acceptance criteria for derusting steel surface

The rust removal level of the steel surface is also the cleanliness. According to the standard “SIS055900” formulated in Sweden in 76, it is the international common standard. “Sa-” (namely spray rust removal method).

4. General requirements for carbon steel surface treatment of marine steel structure coating

- Cleanliness is not less than ISO8501-1 Sa2.5 level (the cleanliness requirements of the surface of the equipment internal coating, splash zone and full immersion zone are Sa3 level),

- The roughness is ISO8503 G (50μm-85μm, Ry5). The stainless steel surface is cleaned and rough by sweeping sand with non-metallic abrasives, and the roughness is about 25μm -45μm;

- The content of surface salt does not exceed 20-50mg/m2NaCl;

- The surface dust cleaning level is above ISO8502-3 level 2.

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