You are here:

Plumbing in the Home/seeping leak in threaded steel steam return


I had a new gas fired boiler installed in my home recently. I had to fight the contractor to return and replace a section of steel pipe they salvaged from the previous installation because there was a pinhole leak in the old pipe. I do not want to have to deal with them again. They replaced the old pipe right up to a second leak I had shown them. It is a steel elbow on the steam return. When it is filled with water (it sits at the lowest point in the system) the threads weep a tiny amount of water. Not enough to overflow the collar of the pipe onto the floor but enough to bug me. Is there a way of sealing the threads without disconnecting the pipe? When it is dry can I apply pipe dope or some other sealer? I tried plumber's putty but that has not stopped it completely.

Hello, I can offer a suggestion but it is hit and miss. Obviously the best way to repair it is to take it apart , Teflon tape and joint compound the threads and re assemble. Quite a bit easier said than done.
There is a product out there call Hercules Pro-Poxy made by the Oatey Co. It comes in a tube that contains a two-part putty. When mixed (kneaded) it turns grey and must be applied quickly. Thumb it into the joint where the threads meet the  elbow, creating a seamless ring around the  pipe. When it dries it is as hard as steel. The important thing is it must be applied tightly to the pipe and fitting with no seams or gaps. There is no guarantee it will seal like the above fix but I have seen no other product work as well as this stuff. Most plumbing supply houses carry it. Not sure about the big box stores.


Plumbing in the Home

All Answers

Answers by Expert:

Ask Experts


Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 40 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

Past/Present Clients
Commercial, residential and light industrial. You name it ...I have probably worked on it

©2017 All rights reserved.