Suction Line Welding

[Brian G]

Hi All -

I'm not a refrigeration professional, but a marine engineer currently working offshore West Africa. Since getting an internet connection on board a couple of months ago, I have found Google pointing me towards this forum several times in response to searches for info on refrigerants, compressor pressures and refrigeration oil so thought it would be prudent to register here in an attempt to absorb some of the wealth of experience and knowledge here through some type of electronic osmosis

I have always thought of refrigeration engineers as akin to magicians of the highest order. Give one some pretty coloured bottles and a set of glass-faced oracle guages and with a wave of their wrench - Abracadabra! You turn summer into winter, and produce ice and snow out of thin air! Pretty amazing stuff!

Anyways..., I do have a question here....

We have a Sabroe A/C system with a SMC 108 S compressor and suction superheat running on R404A. We've developed a crack in a weld on the 4" suction pipe just before the receiver end cover. If I pump the system down to as close to atmospheric as I can, do you think it would be safe to weld up the crack 'in situ'? There's a piece of rubber gasket material held in place by a hose clamp (jubilee clip?) right now, but that's not gonna last much longer. I'd appreciate your thoughts on the matter.

Thanks a lot,
Brian

[HGS]

Hi.
I sugest that you pump down the system by closing the liqid line before the the dry filters and then vent the line.you must not weld with any pressure on the line.

After the welding you must att vacum pump on the cover of the dryfilter and let it run for a night.Also it will be a good ider to chance the dryfilters if you have spares onbord.

Check the reason for the crack.I presume its vibrations from the vessel.

But again no velding on pressured pipes even as it seems at 0 bar

Best Regards
HGS

[Brian G]

After the welding you must att vacum pump on the cover of the dryfilter and let it run for a night.Also it will be a good ider to chance the dryfilters if you have spares onbord.

But again no velding on pressured pipes even as it seems at 0 bar

Oh, dear. I was hoping it might be a 30 minute job..... its hot down here in Africa. Well, at least the deck officers will be happy - as you can see from the attached diagram, I should be able to pump the gas over to the standby compressor and at least keep the wheelhouse cool. The crack is about 5/16" and looks as if it was a welding fault that has recently opened up. Thanks for your advice. Safety First!!

Regards,
Brian

[chillin out]

It is a 30 minute job, just pump down the system until zero pressure and then open the suction somewhere close to the leak (this is to stop pressure building up). If you can't open the pipe somewhere then drill a hole in it and insert a 1/4 access line with a schrader in it (obviously remove the valve whilst brazing).

Repair leak and vac out. Open liquid line and thats it.

Failing that, send me airline ticket and I will come and repair it...lol

Chillin

[Brian_UK]

HI and welcome to the forum, you certainly know how to pour on the charm

If you have any dry nitrogen on board then run that at low pressure through the pipework while you are welding/brazing to reduce the buildup of oxides inside the pipe.

[Brian G]

HI and welcome to the forum, you certainly know how to pour on the charm.

Well..., maybe just a little bit. Its just the appreciation I have for the abilities of the professionals of any field in which I have just enough knowledge to get myself into trouble - be they refrigeration engineers, airline pilots, software engineers, or carpenters. That's one of the great things about the 'net - if I can't find the answers myself, there seem to be any number of people willing to offer advice and share their experience - and for no reason other than to help out some anonymous individual who has asked. Restores my faith in human nature, it does!

Best Regards,
Brian