HOT TAPPING

[QuickFlange]

Hello friends,
Can anyone give some tips? I have an 8" carbon steel under ground gas line to be hot tapped with a branch size 8". My questions :
1. Underground hottapping is it possible?
2. What precautions necessary to have this underground hottapping?

 

[BigInch]

The line will have to be excavated to provide access for cleaning, testing and welding a full encirclement saddle. The excavation necessary to reach and weld the bottom encirclement may be quite deep. If the specific portion of the pipe to be tapped isn't good, another or wider excavation may be needed.

It is usually required to reduce the pipeline's pressure and flow, depending on product, pressures, temperatures and flowrates, the pipeline's configuration and actual connection geometry.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[mizzoueng]

Are there other hot tapping machines out there other than the kind that require a bolted flange and a gate valve to connect to?

I would think to do this you would need to excavate, pour a concrete containment box and add an opening to run the new line that you are tapping for. Then an access door to get to the valve for future line work and a ladder.

 

[QuickFlange]

Thanks Biginch for a quick reply. My specific question is whether any additional supports required to the Run pipe to withstand load of the hottap machine above the Run Pipe? Because once you excavate that means removing the earth under the pipe on which the pipe rests?
I am aware of the other things you have mentioned regarding flow, pressure. I hope these calculations are same as above ground piping except when calculating external pressure the soil pressure may required to be added.

Mizzoueng, Thanks for the reply. Is it the actual method they follow for u/g hottapping? Looks to be very tedious.

 

[Ballbearing1]

TKoilandgas,
There are other ways to hot tap underground and you will not need a valve or concrete containment box.You can install a tee piece in the line,however this would probably work out just as expensive as a valve controlled hot tap.
Cheers
BB

 

[BigInch]

You may have to support the pipe depending on the excavation required. The hot tap machine isn't that heavy and shouldn't have an effect unless the excavation leaves a long span. You should have enough trench support material and sand bags around just in case.

Its unusual to have to install a vault simply for a hot tap, but I wouldn't say you won't have to. Depends on where the hot tap will be located. Under a city street, yes, you'll have to do something.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

Normally you supply the pipe configuration and wall thickness, yield strength, pressure, etc. to the hot tap contractor and let them do the calcs. The calcs are similar to Barlows equation, except you have to know the extent of the weld pool to subtract from the solid pipe wall. The contractor is in the best position to know that.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/