How long does the primer last?
The standard shop paint is intended to protect the steel for only a short period of exposure in ordinary atmospheric condition and shall be considered an impermanent and provisional coating.
Is the shop-applied paint on a joist a universal primer?
Typically, no. But this is a question for the painter who will be applying additional paint to the joists. The joist manufacturer can supply product information to the painter for his use in determining the applicability of additional paint types and finishes.
How is the primer/paint applied?
The typical shop applied primer is a dip applied, air dried paint.
What is the thickness of the primer?
The paint should be 1.0 Mil thick but may vary from as little as 0.8 mils to as much as 2.0 mils. However, since most open web steel joists and joist girders are painted with a dipping process the coating may not be uniform and may include drips, runs and sags.
Is the primer compatible with fireproofing coatings?
It has been found that the SSPC-15 joist primer allows for the adhesion of fireproofing coatings to the joist components. However, check with the specific joist manufacture if the primer coating used is compatible with the fireproofing materials.
Are you able to weld thru shop applied joist paint?
In AWS D1.1 Section 5.15 Welding to Base Metal, it states that one of the exceptions allowing welding is, “Mill scale that can withstand vigorous wire brushing, a thin rust-inhibitive coating, or anti-spatter compound may remain…”. This thin rust-inhibitive coating is essentially the same description of the paint and should be interpreted as such.
Can the joists be provided with different color shop paints?
The SJI member companies have moved to a standard gray shop primer that is a temporary rust-inhibitive coating.