Steam/Condensate Piping
Steam/Condensate Piping
(OP)
We have a problem where we have to replace steam piping which is buried under the ground every year. The piping is black iron and we get tired of replacing it. Any suggestions out there? We have tried stainless, still leaks - we tested the soil and was acididc a few years ago, , we put some lime down in the soil, it lasted a little longer but when the piping had to replaced, it was a mess...





RE: Steam/Condensate Piping
What kind of insulation are you using? Something like Foamglas works well underground, as moisture has no effect on it. Fibreglass and cal-sil just suck up water and hold it against the pipe. The corrosion rate, when the lines are cold, is just spectacular.
There are pre-fab insulated piping systems, but I've always found them extremely expensive, long delivery, and didn't stand up very well. The field joints on the insulation jackets always seem to be a problem. Leaks show up in the jackets after a couple of years (almost always at a jacket field joint), and the vendor and contractor point at each other as to who's at fault. The owner of the line typically winds up eating the repair cost - big surprise.
We insulated the steam lines in Foamglas, then heavy roofing paper (mostly to keep the dirt out from between the cracks in the insulation), and direct buried them. These have lasted for years, going on decades now - as long as they're kept HOT.
The only other solution to your problem involves a tunnel, or a duct with some ventilation. That's expensive up front, and often there isn't room in the ground to allow for it.
RE: Steam/Condensate Piping
RE: Steam/Condensate Piping
These steam lines run to our maint shop and only need to run about 6 months out of the year - what do we do now?
RE: Steam/Condensate Piping
Tim G.
University of Missouri
RE: Steam/Condensate Piping
The one thing about underground steam systems I can state with absolute certainty is - "local conditions dictate what's the right thing to do." What makes perfect sense in one location isn't phyically possible, isn't allowed by code, or just won't stand up someplace else.
Tim - do you leave your lines hot year-round?
RE: Steam/Condensate Piping
Yes, for the most part our lines are hot year-round since we have quite a few steam absorption chillers. We do have some cases where steam is shut off during the summer at the building, but the buried line is left hot and the trap before the service valve takes care of the condensate. In a couple cases though we have left steam off for extended periods of time on the buried piping lines, this will lead to accelerated corrosion. The drain valves are kept open to prevent damage to the piping from condensing steam.
RE: Steam/Condensate Piping
Hope this helps.
saxon
RE: Steam/Condensate Piping
So, Dideyjohn, did your SS piping corrode on the OD, the ID or both?
RE: Steam/Condensate Piping
RE: Steam/Condensate Piping
C4H9NO + H2O = C4H9NOH+ + OH-
morpholine water morpholinium hydroxyl
The volatility is what makes morpholine effective - it carries over with the steam and is recycled in the condensate, maintaining alkalinity throughout, thus reducing corrosion. I would consider this (with the humidifier exception noted) and outer pipe protection as advised above. I agree also with Saxon's post above - deaeration by appropriate pipe design is key. -CB
RE: Steam/Condensate Piping
My suggestion is either one of the followings:
1) Really pay more attention to your deaeration systems (specs normally are 7 pbb for Oxygen and CO2) although this will not handle the Cl2 business but it'll improve the system.
2) Or you can inject chemical treatment compounds.
3) Or change your ground piping to NON-METALLIC piping such as RTR which is really super for underground water business
Wish ya luck