What is the minimum allowable bond strength of SFRM on the primer compared to steel?

The minimum allowable bond strength of Spray-Applied Fire-Resistive Material (SFRM) on the primer compared to steel is specified to be half the bond strength on steel. This requirement is based on the understanding that bond strength can vary depending on the substrate to which the fireproofing material is applied. Steel typically provides a very high bond strength due to its smooth, hard surface, which is ideal for adherence.

However, when applying SFRM over a primer, the surface characteristics may change, leading to a potentially lower bond strength. By establishing a minimum bond strength of half of that on steel, the code acknowledges these differences and sets a realistic benchmark for performance expectations. This ensures that the fireproofing system will still provide adequate protection while considering the variances in adhesion based on surface preparation and material types.

This standard is significant because it ensures that fireproofing remains effective and secure, promoting safety in fire scenarios and adhering to regulatory requirements. It highlights the importance of surface preparation and material compatibility in fireproofing systems.