Replacing Steam Pipe

Steamhead (in transit)

covered in dirt. That's why they failed. They were being attacked from the outside as well as the inside.

When you thread the 3-inch pipe, you won't have to go to the gym. You'll get your workout right there.

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=367&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Matt_61

Replacing Section of 3\" Steam Pipe

I am using a boiler to heat office space and had a bad section of 3" schedule 40 steel steam pipe. I have cut out the 3" pipe and am trying to determine the most economical way to replace it. The pipe I cut out is 28' in length and there are 3 radiators that need to be tied into this 28' section. These sub-lines are 1-1/4". Here are the options I have come up with so far. Please let me know the best way to approach this.

Option 1:

Unscrew the 3" pipe at the nearest joints and screw in new pipe. I have tried using degreaser on the joints and a large pipe wrench with a cheater bar to no avail. The pipe is 50+ years old so I am thinking this method is next to impossible.

Option 2:

Rethread the 3" pipe. I have tried to find a pipe threader to rethread the 3" pipe, however all the pipe threaders at the tool rental places only go up to 2" maximum, so this option is out.

Option 3:

Weld a 3" pipe nipple at each end of the pipe and reconnect the pipe using different screw on fittings (couplers, unions, etc.) I proposed this solution to a welder who looked at the job. He said the problem with doing it this way is that the steam will eventually leak through the fittings. This did not make any sense to me as the old 3" pipe is not welded together - it is screwed into place and teflon tape and pipe dope was put on the threads. He said screw-on fittings won't leak on a 1-1/4" line, but 3" is problematic. He then proposed Option 4....

Option 4:
Welder said the best way to do it was weld the entire section. Meaning he would make a total of 6 welds. One weld at each end, one weld in connect a 21' section to a 7' section, and 3 welds to cut holes in for the 1-1/4" nipples. He then quoted approximately $1,000 to do this which seemed pretty high especially considering I would have to supply the materials.

Option 5:

Have a pipe fabrication company build the pipe. Have them make 4 of the welds at the factory (inserting the three 1-1/4" nipples and welding the 21' section to the 7' section). I would then have this delivered and the welder would only have to do 2 welds at each end.

Option 6:

Have the welder weld a 3" to 2" reducer on each end of the pipe where it is cut. I could then use 2" fittings and pipe to connect the rest of the section together.


I should mention this boiler used to supply about 20 radiators in the building. We have since installed baseboard heat in much of the building so the boiler is only supplying 4 radiators currently. With this in mind, I would think a reduction in the main line from 3" to 2" would have little effect on the rest of the system.

Options 3 and 6 seem to make the most sense to me with option 6 being the less costly of the two since 2" pipe costs less than 3" pipe. However, I am concerned about the fittings potentially leaking later on. Please let me know which option is best.

bob young

hire a qualified steamfitter

you need to subcontract this work out to a competent heating contractor. with all due respect you and the two welders are not qualified to do this job . if you choose to do it , the piping will end up being ripped out & redone. after reading your post i see that you know absolutely nothing about steam or pipefitting & the welders know less. avoid a lawsuit, get professional support.

nicholas bonham-carter

rotted pipe

usually the steam supply pipes are last to rot out [returns are first ]in a steam system.so you need a competent steam man to find out why this pipe failed before simply replacing as it was.[my steam mains are 125 years old!!]
i suspect that sch 40 pipe is too light for steam pipes and if the same installer chose the incorrect pipe he probably chose improper fittings as well.
when a professional steam fitter takes out his saw to cut apipe he studies the layout with the same care and attention as a diamond cutter so that he can reuse the good threads at the beginning of the bad section.
i know that achimedes said:
"Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. "
but he was never a good steam fitter only good for scortched air in those days!!
good luck--nbc

JB_8

pipe

It's just pipe and you got the whole summer to do it. try some http://threepeaksproducts.com/products/gibbslube/

Matt_62

Both the return line and steam line were corroded in the same area. For some reason the pipe in this area did not have any insulation on it and was covered in dirt. I can only assume that over many years the dirt caused both pipes to corrode. The rest of the pipe in the building is okay.

I have done some more research and am going to get a Ridgid 141 pipe threader to thread the 3" pipe. I already threaded the 1-1/4" return lines with a smaller pipe threader. I am then going to put teflon tape and pipe dope on the threads, install the new pipe and fittings, and cross my fingers

Thanks for the responses.

Rich L.

sealing 3 inch pipe

Don't use tape and dope, especially if you're threading the pipes in place. Use a product called Expando and no teflon tape. Just mix a little at a time and coat the threads generously. That's the only stuff I use on screwed steam pipe over 1-1/2".

Good luck, Rich L