GB/T 34202-2017 in English

Substrate surface treatment: Ductile iron pipes and fittings must be sandblasted or shot blasted, with the surface rust removal level reaching Sa2.5 and the roughness Rz≥50μm.

Coating thickness requirements: The minimum average thickness of the inner and outer coatings is ≥400μm and ≥350μm respectively (see Table 4 and Table 5 for specific values). The local minimum thickness of the designated area is 150μm.

Adhesion and impact strength: The epoxy coating must meet the GB/T5210 standard, with the inner coating adhesion ≥8MPa and the outer coating adhesion ≥6MPa. Impact resistance requires no leaks, and the test energy is 3J (hammer diameter 15.9mm) or 5J (hammer diameter 25mm).

International comparative analysis

GB/T 34202-2017 is aligned with ISO 21809-2:2007 in terms of coating technical requirements and test methods, and is optimized in combination with domestic actual conditions.

Implementation suggestions

1. Selection suggestions:Choose the appropriate coating type (fused epoxy powder, solvent-free liquid epoxy or epoxy ceramic inner coating) according to the conveying medium and corrosive environment.
2. Construction precautions:The substrate needs to be transported in time after treatment to avoid secondary contamination; before coating construction, ensure that the substrate temperature is more than 3°C above the dew point and the relative humidity is less than 85%.
3. Quality control:Focus on monitoring coating thickness, adhesion and non-porous indexes, and conduct type tests (such as chemical corrosion resistance and wear resistance tests) when necessary.