Is it acceptable if 2 thickness measurements of a W-shaped column are below the specified thickness of 1-7/16 inch while the rest are adequate?

The situation described revolves around the requirements for the thickness of spray-applied fireproofing on structural elements, such as W-shaped columns. In this case, if the acceptance criteria stipulate a minimum thickness and most measurements meet or exceed that requirement, then the presence of a few measurements that are slightly below may still be acceptable.

Acceptance of fireproofing thickness is often based on statistical and engineering principles, which can justify that as long as the overall performance is not compromised, there can be some minor deviations. This means that if the majority of the thickness measurements meet or exceed the specified thickness of 1-7/16 inch, and the average of all measurements meets the requirements, it could still be considered acceptable.

The key consideration here is that the fireproofing needs to effectively provide the intended level of fire resistance, which typically can be verified through an average or majority that meets the requirement. Thus, if a significant number of the measurements are satisfactory and support the fire protection goals, it aligns with industry practices to view the overall criteria as met. Therefore, approval can be granted even if some individual measurements are marginally below the specified thickness.