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Underground Stainless Steel Piping

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Captdave

Electrical
Jun 14, 2004
1
Need some advice on direct burial of stainless steel piping.

An EPC contractor constructing a new power plant has direct buried high pressure natural gas supply lines to the combustion turbines. There is an insulating flange at either end. The line has not been wrapped for corrosion protection and cathodic protection has not been applied. Is this acceptable? Is there a particular code or standard that addresses direct burial of stainless steel piping? I appreciate any advice.
 
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FWIW, when we were looking at changing to stainless steel tubing for hydraulic lines, one concern of the vendor was that ss inside rubber clamps, in the ABSENCE of air, would not form its proper protective coating and corrode. He referenced buried underground, below water table, ss tubing as a particular problem.

I have no further info, and think there may have been much old wives tale there, as we have had no problems with the ss under the rubber clamps.

kcj
 
Captdave;
One concern regarding direct burial of ss piping is the potential for MIC (microbiologically influenced corrosion) damage on the OD surface in contact with the ground. I would review soil conditions and determine how the piping was buried (trenched with backfill - gravel or sand).

The piping code that would apply would be ASME B31.3. However, this is geared for design and does not address corrosion issues related to burial.

For information on Corrosion of SS in Soil, please see the following web site;


After you enter, navigate to the Materials and application and other documents. You will find a technical paper on corrosion of stainless steels in soil.
 
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