What is the Wet Mil and Dry Mil this product should be installed at?
Hello,
The required thickness of Fire Finish 120 will be determined by the size of the steel and the UL Design Number you are following. I have attached all of our UL Designs for the Fire Finish 120 product to this response. There is a design number for a floor assembly supported by a beam (D990), a design number for a beam (N640), a design number for a solid steel (wide flange) column (Y633), and a design number for a hollow structural steel column (Y634).
Once you have determined what listing you will need to follow, you will need to determine the size of the member. For beams and wide flange columns these are pretty standard and shown in the table on the listings. For hollow structural members there is some calculation that is required based on the dimensions of your steel member.
The last attachment I have added is the estimating tool. This will be the best resource for all of our steel protection products and tell you the listing it is referencing for the values it provides. This is also a great tool for calculating thicknesses needed for the hollow structural steel members. This tool can be used to estimate the WFT (wet mil thickness) and DFT (dry mil thickness) needed for your application.
If you member is not one that is listed in the estimator or any of our listing you may require an engineering judgement (this may also be needed for any condition specific issues like inaccessibility due to proximity to a fire rated assembly). If you are needing an engineering judgement for this condition please send in an email to USSPEng@hilti.com. Please include an architectural drawing for the condition needed to be addressed and indicate any fire-resistant rated construction in the drawings. Please also provide the sizes of the steel members (typically length x width x thickness).
Thank you,
Alex Hernandez
Senior Steel Protection Engineer
