Stud Welding & FIRETEX

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Technical Advisory Document TAD0011

Stud Welding on FIRETEX Coated Beams

It is the opinion of Leighs Paints that where stud welding has taken place on the top uncoated flange of a beam coated with a FIRETEX material, and this welding has resulted in the formation of blisters in the coating on the inner top flange, these blisters do not need to be repaired from a fire protection point of view.

This assumes the studs are at least at 80mm centres.

However, where any or a combination of the following apply, then it will be necessary to repair the blistered area:

1. Where aesthetics are a prime consideration
2. Where the construction is still open to the elements and blisters have cracked
3. Where the end use situation will fall into categories C2-C5 as per ISO12944-2:1998(E). i.e. external exposure or internal environments where condensation and/or high humidity may occur
4. Where blisters have completely detached from the structure

Repair Procedure

1. Remove all blistered paint back to a firm edge. This includes the primer if this too is damaged, in which case it will be necessary to reapply with a suitable primer
2. Ensure surfaces to be coated are clean, dry and free from all surface contamination
3. For areas of repair up to approximately 25cm² use FIRETEX M72 mastic, levelling off with the previously applied coating. For particularly high dry film thicknesses more than one application may be necessary. In all instances some shrinkage will occur on drying and a second application of M72 may be necessary
4. For areas of repair of greater than 25cm² the original intumescent coating should be applied by brush or spray in the appropriate number of applications until the original target thickness for the section is achieved
5. Topcoat as required

NOTE: For repair of FIRETEX M95, do not use M72, but repair with either M95 or M90.

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