GB/T 31405-2025Test method for the cathodic disbonding of pipeline protection coatings subjected to elevated temperatures (English PDF)

1 Scope

This document specifies the principle, test medium, test equipment, test specimens, test procedures, and test parameters for the high-temperature cathodic disbondment test of pipeline anti-corrosion coatings.

Test results, data processing, and test reports.

This document applies to the testing of the high-temperature cathodic disbondment resistance of the anti-corrosion coating of buried pipelines with cathodic protection and operating temperatures above 25°C.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

GB/T 1266 Sodium Chloride Chemical Reagent

GB/T 6682 Specifications and test methods for water used in analytical laboratories

3 Terms and Definitions

The following terms and definitions apply to this document.

4 Principles

In high-temperature environments, after cathodic protection is applied to anti-corrosion pipelines, cathodic current may occur at defects in the pipeline's anti-corrosion layer.

The reduction reaction produces gases and OH- ions, which peel off the anti-corrosion layer. By artificially creating defects in the pipeline's anti-corrosion layer, the corrosion can be simulated.

Under high-temperature conditions and cathodic protection, a constant potential is applied to the pipeline for a specified time, causing a reduction reaction at the defect site, producing...

Gases such as OH- are used to peel off the anti-corrosion layer. After the test, eight evenly spaced radial scratches are made outward from the edge of the test hole to remove the anti-corrosion layer.

Cut the line, pry off the anti-corrosion layer with a blade, measure the peeling area along the edge of the defect, calculate the average radius, and characterize the cathodic stripping degree of the pipeline anti-corrosion layer.

GB/T 37309 | GB/T 35505 | GB/T 31566 | GB/T 19824 | GB/T 31404 | […]