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Posted by Wally on April 28, 2006, 2:18 pm
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The main work on this job is painting 1200 feet of 2" pipe that
carries compressed air for running pneumatic tools. It runs on top of
and down the length of a pier over salt water. There are two legs
that go under the pier to provide air manifolds to the opposite side
of the pier. These see direct exposure to salt water. These two
legs are severely rusted, typical for the pipe location and lack of
maintenance. It's a bugger to reach, high tide only and from some
sort of floating platform. Because of the salt water exposure I want
to put up something that will last a fair amount of time and that is
why I am choosing welded fittings. No threads or thinner spots to
rust through. Threaded fittings are allowed, but this is my choice.
As far as hazard goes, the worst thing that could happen if one of my
joints fails is some fish would get scared and I'd have to fix it.
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Posted by Ignoramus22287 on April 28, 2006, 3:25 pm
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> The main work on this job is painting 1200 feet of 2" pipe that
> carries compressed air for running pneumatic tools. It runs on top of
> and down the length of a pier over salt water. There are two legs
> that go under the pier to provide air manifolds to the opposite side
> of the pier. These see direct exposure to salt water. These two
> legs are severely rusted, typical for the pipe location and lack of
> maintenance. It's a bugger to reach, high tide only and from some
> sort of floating platform. Because of the salt water exposure I want
> to put up something that will last a fair amount of time and that is
> why I am choosing welded fittings. No threads or thinner spots to
> rust through. Threaded fittings are allowed, but this is my choice.
>
> As far as hazard goes, the worst thing that could happen if one of my
> joints fails is some fish would get scared and I'd have to fix it.
Another hazard is that the work would stop until someone is around at
low tide to fix these pipes, which could be quite an expense. Also, if
they start developing pinholes, a lot of air could be lost due to them
and result in extra work/wear and ear on the compressor.
How about you do some experimenting, take a few realistic pieces of
pipe (preferably with the right quantity of rust), and try to weld it,
then try to find out the strength of the welds by various methods.
I am afraid that you would have some unpleasant surprises.
i
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Posted by Robert Ball on April 28, 2006, 10:33 pm
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> Piping systems are typically pressure tested at 1.5 times the working
> pressure, or about 190 psi in this case. You would need to groove the
> joints to get good penetration, then weld, then clean up, and need a
> clean interior flow channel. While you may be able to roll a portion
> of the pipe, the ends will need to be welded in place, which means
> vertical and overhead as well as flat or horizontal position butt
> joints. 50' is only going to be a few joints, assuming some bends.
> Threaded sure looks like the preferred alternative. 2" is frequently
> used as an upper limit for threaded, sometimes up to 4" before going
> to welded joints; you have a lot more pipe to work with and a lot less
> curvature than with small pipe sizes.
>
> Wally wrote:
>
>> I"m looking at a job that will replace about 50' of 2" black steel
>> pipe that handles 125 PSI compressed air. There is 110 power at the
>> site that would run my little Lincoln SP 100 just fine. I've got .030
>> flux core wire to run in it, so the penetration should be fair. I'd
>> like to hear some opinions on whether this will do a satisfactory job.
>> The only inspections will be visual and it can't leak. Thank you for
>> your time.
>>
>
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Posted by herman munster on April 29, 2006, 8:32 pm
Please log in for more thread options > Why not just use threaded pipe?
>
Well, then it wouldn't be welding, it would be something for
sci.engr.joining.threaded.
Bwahahah, I couldn't help myself ...
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Posted by Eide on April 29, 2006, 5:56 pm
Please log in for more thread options What about using hose rated for chemicals and UV exposure? There are a
million types of hose - look in McMaster for something that won't corrode in
the salt. You can get them with bronze fittings.
> I"m looking at a job that will replace about 50' of 2" black steel
> pipe that handles 125 PSI compressed air. There is 110 power at the
> site that would run my little Lincoln SP 100 just fine. I've got .030
> flux core wire to run in it, so the penetration should be fair. I'd
> like to hear some opinions on whether this will do a satisfactory job.
> The only inspections will be visual and it can't leak. Thank you for
> your time.
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> carries compressed air for running pneumatic tools. It runs on top of
> and down the length of a pier over salt water. There are two legs
> that go under the pier to provide air manifolds to the opposite side
> of the pier. These see direct exposure to salt water. These two
> legs are severely rusted, typical for the pipe location and lack of
> maintenance. It's a bugger to reach, high tide only and from some
> sort of floating platform. Because of the salt water exposure I want
> to put up something that will last a fair amount of time and that is
> why I am choosing welded fittings. No threads or thinner spots to
> rust through. Threaded fittings are allowed, but this is my choice.
>
> As far as hazard goes, the worst thing that could happen if one of my
> joints fails is some fish would get scared and I'd have to fix it.