07ST Series Stainless Steel Union Tank Tee Installation

A FAQ about the installation of the 07ST Series Stainless Steel Union Tank Tees is whether a thread sealant is required on the union nut thread.

The answer is no! You do not require P.T.F.E. tape or pipe dope for joining the union connection thread on our 304 stainless tank union tank tees. The union thread is an NPSM (National Pipe Straight Mechanical) and the union on the tank tees rely on an O-ring type seal.

This brings us to the second part of this question regarding the concern of galling. We have never heard of any issue in the field with galling (cold welding) of the threads when tightening the union nut. This is due to several factors that reduce the risk of galling.

#1 - Low assembly speed by hand turning and the low torque requirement of hand tight plus a ¼ to ½ turn with a channel lock for wrench tight does not create any heat.

#2 – Good quality, smooth machining of the threads virtually eliminates “pick-up” and the risk of galling.

Union Nut Installation Tip:

It is never a bad idea to take extra precautions. If you have any concern regarding galling simply apply a Stainless-Steel Grade Anti-Seize Compound to the NPSM union thread, although this is not necessary from our experience. We have had feedback from some installers who do apply a light application of Gray Magic compound as an "anti-galling” agent not as a thread sealant. This does not have any negative effect on the NPSM union thread which has the same 60-degree angle as the NPT thread. However, NPSM threads can not form a seal using its thread, it needs an O-ring to form a seal.

Tip for All NPT Threaded Connections:

For the NPT tapered pipe thread connections including the tank, line (inlet & outlet lines), and four accessory port connections for the pressure gauge, pressure switch, relief valve and sediment faucet we do recommend the use of both P.T.F.E. thread sealing tape and a quality thread sealing compound such as Gray Magic.

https://support.boshart.com/making-a-leak-proof-stainless-steel-threaded-connection