Steam Pipe repairs

[mike202]

Need to repair a small gouge(1/16" deep X 2 " X2") on a Sched 40-A53 steel steam pipe. Pipe is 14" dia.operating at 100 PSI and 338 degree. I am considering a 6" X 6" X 3/16 steel patch. Repair needs to be done without shutting down the steam pipe.
Has anyone done this before? What temp/rod do you recommend?

[enlpck]

First the warning: If you have to ask, you probably shouldn't do the repair. Steam lines, boilers, etc, carry a high risk, and in many jurisdictions (states, proviunces, cities like NYC, etc) this work requires appropriate authorization (NBIC R-stamp, approval of jurisdictional or underwriters inspectors, etc). That said....

DO NOT put a patch over it. This patch may end up being the pressure boundary it the pipe erodes through or has a crack in the area under it, and may hide cracks that can run and produce complete failure.

This should also not be done without relieving the line. The wall may blow through under the puddle, leading to molten metal being steam propelled, followed by the steam. I have seen the results of this. DO NOT weld on pressurized steam lines.

The repair should be done by: relieving the pressure on the line. Check the area for cracking (dye pen or mag particle is ok, UT will show thickness as well). CLean thoroughly. Pad up with 7018 and blend the weld in to eliminate stress risers. Recheck for cracking.

Again, DO NOT weld on pressurized steam lines. Or air lines. or.... IT is a specialty with particular safety concerns and requiring training.

[billsss]

I wouldn't do it!
Safety first!
That is a bad day in the making. Is it leaking? What happens if you blow through? Steam burns at the very least depending on the size of the area and amount of steam. Could = one cooked welder.
Cons-Loss of the plant with a steam rupture, OSHA reportables, injured/dead employee,torn up equiptment.
pro's plant keeps running.
I'd say the cons have it.
Shut it down to fix it right. If it's not that bad a leak, keep an eye on it and wait for a shut down period.

[mike202]

The pipe was UT'd and is in excellent condition-no corrosion. The UT picked up the scratch(gouge) in the pipe..i3in. depth vs .35 wall. Now we are considering a patch of some kind over the scratch. This is buried steam pipe.

[billsss]

I stick by my previous answer. Too dangerous! Adding enough heat to weld on a patch will be adding stressors at pressure and temperature that cannot be known. Adding a trench I assume with limited egress spells dissaster. At least get an engineering firm involved to evaluate. The consequences and liability in continuing is enormous both to the company and the individuals doing the work.

Your brain is telling you to ask for a reason. It doesn't smell right. Back off and properly evaluate!

[billsss]

OSHA regs 1910.146 covers confined spaces such as trenches
1910.147 covers lockout/ tagout requirements including hot taps.
I suggest at a minimum reviewing these sections as well as involving an engineering firm to evaluated the needed repairs and situation. I am not trying to keep you from getting the job done but putting someone at personal risk should not be done unless well thought out, planned and all other avenues have been exhausted.

[Bob the Welder]

By enlpck:

First the warning: If you have to ask, you probably shouldn't do the repair. Steam lines, boilers, etc, carry a high risk, and in many jurisdictions (states, proviunces, cities like NYC, etc) this work requires appropriate authorization (NBIC R-stamp, approval of jurisdictional or underwriters inspectors, etc). That said....

DO NOT put a patch over it. This patch may end up being the pressure boundary it the pipe erodes through or has a crack in the area under it, and may hide cracks that can run and produce complete failure.

This should also not be done without relieving the line. The wall may blow through under the puddle, leading to molten metal being steam propelled, followed by the steam. I have seen the results of this. DO NOT weld on pressurized steam lines.

The repair should be done by: relieving the pressure on the line. Check the area for cracking (dye pen or mag particle is ok, UT will show thickness as well). CLean thoroughly. Pad up with 7018 and blend the weld in to eliminate stress risers. Recheck for cracking.

Again, DO NOT weld on pressurized steam lines. Or air lines. or.... IT is a specialty with particular safety concerns and requiring training.
Reply With Quote

Excellent advice! Please heed for the safety of yourself as well as others!

[Supe]

If the pipe wall thickness is .35 as you state, you can pretty much forget welding on a hot line, ESPECIALLY steam. Most of the people who do hot welds are fluid backed, NOT steam. Pneumatic pressure vs hydraulic pressure are two VERY different circumstances.

I would HIGHLY suggest you talk to a company that specializes in hot tapping and see what their suggestions are. They will most likely refer you to SEAL-EX, Colt, Furmanite, Clock Spring, Mexxsub, Plidco, Oil States, etc, whom all provide clamping systems for epoxy grout.

At 100 psi steam, this more than likely will fall under the B31 standards, in which case your AI will tell you you're nuts. You will also need this work approved by a PE, who will in all likelihood agree with your AI. With that sort of wall thickness, a welded repair just isn't going to happen.

[mike202]

Thanks for the feedback. We certainly don't take any chances when it comes to safety.There is no leak at the scratch. We were being precautionary in case the steel corrodes at the scratch 20 years from now. We will probably look into a wrap around or split coupling for steam application. Any favorite models?

[billsss]

I'm glad that is your decision. Not knowing you, your intial post did make my sphincter contract a little.

As SUPE stated- SEAL-EX, Colt, Furmanite, Clock Spring, Mexxsub, Plidco, Oil States, etc, whom all provide clamping systems for epoxy grout.

I would recommend Furmanite. I have worked for Furmanite and used them in a powerplant setting. I know they offer quality components and service. They will come onsite, provide recommendations and measure for the final product themselves and install it.

[jdh239]

Not fun --- Steam pipe explosion in NY -- That should scare the crap out of you... I know it would me

You Tube

You Tube

[WHughes]

I have seen the video of this steam burst in NYC from a different camera and there is a full size tow truck with 2 occupants in the crater made from the steam explosion. No one knows how they survived but the hole was about 30 feet deep and about 40 feet across.

[snoeproe]

Do you have pipe welding tickets?
If not, your not the guy to be repairing this pipe.
If you do have pipe welding tickets, NEVER weld on a pipe that has not been isolated and de pressurized of it's contents, especially with steam.
Until the pipe can be shut down then it can't be welded or repaired.
Steam pipes (and any pressure pipes for that matter) have to repaired by following code, without question.

[WHughes]

I wonder if a bypass can be constructed and engineering come up and approve a procedure for a hot tap.

[weldbead]

Originally Posted by jdh239

Not fun --- Steam pipe explosion in NY -- That should scare the crap out of you... I know it would me

http://www.youtube.com/watch?v=SImhkapRuIs

i loved that explosion..my daughter was living in nyc when it happened and it was the final straw that convinced her to move out..

[Xtreme Fabrication]

Originally Posted by mike202

Need to repair a small gouge(1/16" deep X 2 " X2") on a Sched 40-A53 steel steam pipe. Pipe is 14" dia.operating at 100 PSI and 338 degree. I am considering a 6" X 6" X 3/16 steel patch. Repair needs to be done without shutting down the steam pipe.
Has anyone done this before? What temp/rod do you recommend?

You need your head examined. As everyone else here has stated this is a bad idea. I have done a lot of work in a large steam plant owned by federal Gov. We used to do 24 hour to 48 hour shut downs. Where we would shut down the entire system to do work on the lines or in the tunnel system. You are going to have to shut down the system, bleed off the pressure, let it cool down to less than 100 degrees, weld up, turn system back on. I am surprised that you're not being required to cut the line and replace the section. That piece is considered damaged and needs to be replaced not repaired. It would never pass any new construction inspection if you did that.

[TozziWelding]

Shut down the line cut out the offending section and weld in a new one, no screwing around with steam.