gas pipe union

[jocar]

When you disassemble a union on black steel pipe to change out a gas water
heater do you use anything on the two metal surfaces of the union to seal it or is it better without any sealant or oil on it when you reassemble the union.

 

[Haworthplumbing]

You can put a little pipe dope on it that's rated for gas. Usually tho if it lines up good use two wrenches. One on the union nut and the other to back up one of the other sides so it doesn't spin when you give it a good tightening. Make sure ya soap test it for leaks when your done.

 

[phishfood]

If you use pipe dope on the face, a super thin smear with your finger should be all. Any appreciable buildup will cause problems. And definitely, none on the threads.