Repair Welding on Water-filled Pipe
Repair Welding on Water-filled Pipe
(OP)
Greetings all. We are doing some maintenance on a major water pipeline in our Agri-business. This requires welding a steel plate to "patch" a leak. As the repairs are being done, water is being transferred through the pipe.
Will this seriously affect the weld penetration? Will the weld be less reliable due to the heat transfer with the water?
Will this seriously affect the weld penetration? Will the weld be less reliable due to the heat transfer with the water?





RE: Repair Welding on Water-filled Pipe
The welds will be ugly, too.
That will make the welders unhappy.
BTDT. At night, in winter, on a tower.
Thankfully, there was no wind.
There was no wind because it was well below 0F.
Okay, I was holding the cable so it wouldn't slither back down the tower.
Mike Halloran
Pembroke Pines, FL, USA
RE: Repair Welding on Water-filled Pipe
RE: Repair Welding on Water-filled Pipe
I assume one critical factor is safety of the welder from electrical shock. A leaking pipe means that the ground on which he is working is damp - probably an electrical shock hazard as well?
Thanks for the help.
RE: Repair Welding on Water-filled Pipe
One piece of information that you need to know is that the water leak MUST be stopped before welding both for welder safety and weld quality. There are various ways to do this -peening or use of freeze plugs to isolate the line for weld repair.
At our Power Plants we have on occasion needed to repair low pressure service water piping systems. A weld procedure for water-backing was qualified in accordance with ASME Boiler and Pressure Vessel Code, Section IX.
RE: Repair Welding on Water-filled Pipe
Ed Danzer
www.danzcoinc.com
www.dehyds.com
RE: Repair Welding on Water-filled Pipe
RE: Repair Welding on Water-filled Pipe
One serious concern is the condition of the pipe. If one area failed there could be other thin or corroded areas near by. The weld patch will increase local stresses. I have heard stories of entire patches blowing out due to thinned pipe walls.
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Plymouth Tube
RE: Repair Welding on Water-filled Pipe
good luck
CM
RE: Repair Welding on Water-filled Pipe
There is quite a bit of information about in-service welding for pipelines (mostly natural gas and oil from what I've seen). There are some fairly expensive computer models to help select the welding parameters.
If this is a onetime thing you don't want to go to the work of researching and qualifying a procedure for future use, you may want to contact a pipeline contractor who has experience doing this type of work. They can probably help you out with a procedure as well as provide welders who have experience with in-service welding. Look for contractors who do work for oil and gas companies, or who specialize in hot tap work. Sleeving over leaks and damage is fairly common for some pipeline companies.
RE: Repair Welding on Water-filled Pipe
What location around the pipe? (Top, side, upper 45, low 30 degree point, bottom, on an elbow or bend?)
Can you get to the break? (Is it in mid-air, near the ground waist high, or under the pipe in a water-filled ditch?)
Is the (current) outside of the pipe nice and smoothly prepped? Did the break cause deformations and raised or cracked or broken-out parts of the pipe where the new patch can't sit smoothly?
RE: Repair Welding on Water-filled Pipe