Installation of Corrosion Coupon on bottom of pipe as opposed to top? 1

bgeyedog · Jun 18, 2009

On a recent project our Middle East Client requested corrosion coupons be placed at the 6 o'clock position as opposed to the 12 o'clock position on the pipe. There are several problems this has created.
1) Pipe is large diameter 36", 30", 16" and 4" but all pipe is buried 1 meter to TOP and a Valve Pit is required to maintenance these.
2) We are talking hazardous chemicals H2S etc. being able to sink into this space not to mention any spills that might occur.
3) Construction headaches for the contractor in having to build 15 feet deep valve pits and maintenance headaches.

Nonetheless it is what client want's. Has anyone had experience with this type of install?
Dumbfounded in Bakersfield, CA
bgeyedog

SJones · Jun 18, 2009

It's a common fault: contractors don't want to put access fittings and the associated pits at the bottom of the pipe because it's costly and time consuming, so they take the easy way and fit them at 12 o'clock. The trouble is, generally, the water (and the corrosion) is at the bottom of the pipe. Now, you could suspend the coupons from the 12 o'clock position to try and dangle them in the water at the bottom of the pipe but those nasty operations people want to run pigs through the pipe and, guess what, your coupon holding arrangement is in the way!

Yes, the fittings and pits will be an HSE risk in H2S service but that is for the operator to manage.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

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Installation of Corrosion Coupon on bottom of pipe as opposed to top? 1

bgeyedog

Petroleum

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SJones

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