Maintenance & Technical > KX500 Original

Pipe Repair

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mdw471:
Hi All

plugging the ends of the pipe and using air pressure or heat to 'expand' the dent out works great......but a bit of a heads up

heating a chamber with trapped air can be dangerous. the air expands to the point where if something fails or is torched thru the whole thing can go 'BOOM'....actually i have never seen/heard anything more than a decent 'pop', but holy cow that was enough!!

instead, fill the chamber with water and as little air as possible. the water will expand enough to force out dents, but not enough to pop. any failures result in a 'pisser' until the pressure balances out

for whatever it is worth

Mark

Johnniespeed:
 Hi Mhardee
   A friend of a friend who lives nearby has jigs set up for pipe repair. I had him extract several. He has some type of plugs for the ends, pressurized it with air and gently heats the area. This works perfect. The surface was only slightly discolored but the dents were gone. I am sure there is someone near you who has perfected this craft also.  I am grateful this guy lives close and only charges $25.   
   I have seen adds in magazines for pipe repair too.
   John

don46:

--- Quote from: mdw471 on September 05, 2007, 05:42:12 AM ---
instead, fill the chamber with water and as little air as possible. the water will expand enough to force out dents, but not enough to pop. any failures result in a 'pisser' until the pressure balances out



--- End quote ---
I've poped dents   many pipes, in fact I made some trick adapters to plug the ends of the pipe, even though I've always been leary of the blow up, and as such I tried the process described with the water, it was the only time I've had a pipe rupture. The water dissipates the heat, once you have enough heat to expand the dent the water is so hot it turns to steam and expands rapidly and ultimately I had a hole. I work in the Industrial gas business and have a real appreciation for what compressed air/gas can do which leads to my healthy respect for the possibility of a failure, always wear gloves and safety glases, I even use a leather welding jacket wrapped around the pipe except where I'm working.

mdw471:
Don46

so no problems with just air??

hmmmmmm

Mark

don46:
Think about the expansion rate of air, OK now think about the expansion of water. To get the dent out you have to get the area hot enough to make the metal pliable, and in doing so the water gets hot enough to boil at the are being heated, turning to steam and since you have no room to expand because of the water the pressure rises rapidly. I thought this was a good idea as well, if there was a rupture it would be hydralic rather than pressure leak.  I think there is the poetential for failure using air as well, I haven't had a problem. 

I have heard of water being used, but rather than heat the pipe is put in the freezer, when the water freezes it expands and pops out the dent.

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