How do you use instruments and standards to measure coating thickness and adhesion?

1 Pre-inspection preparation

Prior to conducting the corrosion and coating inspection, the mechanical inspector should create a detailed inspection plan that outlines the scope, objectives, criteria, methods, and procedures. To accurately measure coating thickness and adhesion, the inspector should acquire the necessary instruments and tools such as magnetic gauges, ultrasonic gauges, pull-off testers, and cross-cut testers. Furthermore, the inspector should be aware of the relevant standards and codes such as ASTM, ISO, NACE, and SSPC that define acceptable levels and requirements of corrosion and coating. Lastly, to ensure safety during the inspection process, the inspector must wear appropriate personal protective equipment (PPE) and take necessary precautions to avoid exposure to hazardous substances and environments.

3 Coating adhesion measurement

Another key parameter of coating quality is the coating adhesion, which indicates the strength of the bond between the coating and the substrate. The mechanical inspector should measure the coating adhesion using the appropriate instrument based on the type and condition of the coating and the substrate. For example, pull-off testers can be used for tensile adhesion, while cross-cut testers can be used for cross-hatch adhesion. The inspector should follow the calibration, operation, and maintenance instructions of the instrument, as well as the sampling, testing, and reporting procedures of the standard. The inspector should also compare the measured values with the specified values and record any deviations or non-conformities.

4 Coating defect identification and correction

During the corrosion and coating inspection, the mechanical inspector should also identify and correct any coating defects that may compromise the quality and integrity of the coating. Common defects include blisters, cracks, flaking, runs or sags, and wrinkling. The inspector should assess the cause, extent, and severity of the defect, then take corrective action such as re-coating, patching, or stripping. It is important for the inspector to document the defect and related action taken.

5 Inspection documentation and reporting

The final step of the corrosion and coating inspection is to document and report the results and findings of the inspection. The mechanical inspector should prepare a comprehensive and accurate inspection report that includes the identification and description of the inspected equipment or structure, the inspection plan and scope, the inspection data and measurements, the inspection analysis and evaluation, as well as the inspection recommendations and actions. Supporting documents such as photographs, drawings, certificates, or test results should also be included. The inspector should then submit this report to relevant parties for review and approval.