Inspect intumescent dry film thickness: read the gauge survey and findings
A laboratory's gauge report includes satisfactory web measurements and flagged flange-edge locations. The foreman needs to understand the actual findings before directing correction or accepting an overall summary.
Read the survey's method, measured layer and locations against the actual requirements. ASTM D7091's public scope distinguishes calibration, verification and adjustment, and warns that a single point may not represent a coating system. It supplements instrument instructions rather than replacing them. The governing requirements decide the relevant thickness and evaluation; this outline supplies no universal reading count or averaging tolerance.
Keep the coating decision traceable
- Identify the reported scope. Check the agency, date, product, member references and surfaces surveyed. Match them to the current protection plan and design information. Ask for clarification of a vague area label rather than assuming that measurements from selected columns address all the beams on the same floor.
- Read the instrument assurance record. Find the applicable method and the reported calibration, verification and adjustment information. Ask the qualified inspector about missing evidence and relevant instrument limitations. Those terms are not interchangeable; a certificate alone should not be described as the complete record of an instrument's actual use on this survey.
- Confirm the coating layer represented. Ask how the survey establishes intumescent thickness when primer or topcoat is also present. Keep layer information and the actual calculation or assessment method visible. A gauge value described as total coating thickness should not be relabelled as intumescent thickness without the supporting method.
- Follow the measurement and evaluation arrangement. Locate individual readings, defined measurement areas, reported summaries and governing criteria. Ask the inspector how they relate to the member surfaces. Do not invent a minimum reading count, average away a flagged edge or apply another project's low-reading rule to this report.
- Translate findings into a defined response. Mark affected members and surfaces and obtain the required technical direction. Coordinate access, directed correction and specified follow-up. Label crew measurements accurately while the responsible inspection and acceptance process continues; an extra coat alone does not close an agency finding.
- Keep original and follow-up evidence together. Link the response and later survey to the original flagged locations. Record the actual acceptance decision and its scope. A revised summary should explain what changed rather than erase the initial finding, and a selected-member survey should not become a whole-building certificate.
Common mistakes
- Calling a total coating reading the intumescent layer.
- Replacing individual findings with a favourable summary.
- Treating instrument terms as interchangeable.
Checklist
Read six survey references
- Agency, date, members and surfaces.
- Actual method and instrument evidence.
- Coating layer and calculation basis.
- Measurements, summaries and criteria.
- Directed response and follow-up locations.
- Acceptance scope and retained original findings.
Check your understanding
Can a satisfactory average settle a flagged flange-edge result without reading the governing criteria?
