Squirter DTI FAQs > Squirter DTI's and Painted Steel Surfaces?

How well do Squirter DTI's work over painted steel surfaces?

These photos will serve to illustrate this situation.

Usually the paint is held back around the bolt holes and applied to the connections AFTER tightening the bolts. In this case the Squirter DTI's bear directly against uncoated steel surfaces, and of course function correctly.

Recently, there have been some projects on which the steelwork is ENTIRELY shop painted, sometimes with several coats, including on the outside of the connection and on the faying surfaces. Then, when the bolts are installed with Squirter DTI's, the Squirter DTI bears directly against a painted surface.

In the majority of these situations, once the paint has cured correctly, Squirter DTI's function correctly and squirt as expected. In a very few of these situations, however, some problems have been reported, as evidenced by the Squirter DTI's apparently NOT firing as expected.

Here are some guidelines to bear in mind when contemplating placing a Squirter DTI over a painted steel surface:

1. Over single coat paints such as inorganic zinc or even the old red lead, no problems have been reported.
2. Over two coat systems such as 100-150 microns epoxy primer and 125 micron urethane top coat, such as in many power plants, no problems have been reported.
3. Over three coat systems such as inorganic zinc primer 75mm, intermediate coat Polyamide epoxy 125mm, and finish coat Modified Aliphatic Polyurethane 75mm, sometimes used in chemical plants, some problems have been reported when the system (usually the intermediate coat) has not cured properly.
4. Any coating, especially the two and three coat systems, WHEN NOT CURED PROPERLY, will cause some Squirter compatibility problems.
5. When the total thickness is greater than 400 microns, EVEN WHEN FULLY CURED IF THAT IS POSSIBLE, there are likely to be Squirter compatibility problems.
6. If the Squirter compatibility problems cannot be solved any other way, put a hardened flat USS washer under the Squirter DTI, and it will squirt correctly.

FAQs - Squirter DTIs