What are the specifications for the application and acceptance of anti-corrosion coatings on industrial pipelines?

This post was last edited by Wang Wei2 on 2026-4-9 at 09:39. GB/T50726-2023 is the current latest **standard** for the application and acceptance of anti-corrosion coatings on industrial pipelines; it came into effect on September 1, 2023, replacing the previous standards GB50726-2011 and GB50727-2011. This standard integrates construction and acceptance requirements to form a unified technical framework, applicable to corrosion protection projects for new, renovated, and expanded steel and cast iron equipment and pipelines.

This post was last edited by Wang Wei2 on 2026-4-9 at 09:51. There is no unified style or format for inspection sheets related to anti-corrosion work on equipment; generally, such sheets are developed based on the key aspects of anti-corrosion inspection for pipes and equipment, including surface treatment, coating quality, construction conditions, and acceptance testing, in order to create inspection sheets that suit specific needs. In accordance with relevant engineering specifications, the anti-corrosion inspection of pipes and equipment focuses on the following aspects: 1. Surface pretreatment inspection – Cleanliness: The metal surface must be free of oil, dust, rust, and residues from previous coatings; sandblasting should achieve a Sa2.5 grade, or manual rust removal should reach a St3 grade. Roughness (anchor pattern depth): Generally, it should be between 50–90 μm; this is measured using an anchor pattern gauge. Humidity control: Ensure the surface is dry before construction; the relative humidity should not exceed 85%, and the surface temperature of the steel pipes should be at least 3°C above the dew point temperature. 2. Inspection of anti-corrosion materials and construction techniques: Material compliance: The coatings or anti-corrosion tapes used (such as epoxy coal tar pitch, polyethylene tape, FL-833 vinyl resin + glass fiber cloth) must come with quality certification documents and be within their shelf life. Coating structure: For processes such as “four layers of fabric and six layers of paint”, application must be carried out layer by layer, with each step’s adhesion checked. Overlap width: For spiral-type anti-corrosion coatings, the axial overlap should be at least 50% of the coating width, while the overlap at the start and end should be at least 100 mm or 1/4 of the pipe’s circumference. Coating quality inspection – Thickness measurement: A coating thickness gauge is used to select multiple points evenly along each section of pipeline or equipment, to ensure that the thickness meets the design requirements. Visual inspection: The coating should be smooth, free from defects such as bubbles, cracks, sagging, and missed coating areas. Adhesion test: Sampling is carried out using the scratch method or pull-off method to ensure a strong bond between the coating and the substrate. Spark leak testing: A 100% pinhole inspection of the coating layer is carried out; for example, the enhanced anti-corrosion leak testing voltage is 5 kV or 10 kV. Any leaks detected must be marked and repaired. 4. Records of environmental and construction conditions: During construction, the ambient temperature should be between 5°C and 35°C, with humidity below 85%. Record the construction time, operators, equipment calibration status, and process parameters. 5. Completion inspection and document archiving: After completion, comprehensive tests such as water filling for leak detection and cathodic protection potential testing (if applicable) are required. Submit a complete record form, including: construction logs, material certificates of conformity, inspection data for each stage, photographic evidence, and signatures of all parties confirming approval.