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lantulu
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Join Date: Mar 2014
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Buried Flange in Hydrocarbon Service

03/13/2014 3:01 AM

Could anybody tell me under what circumstance or condition is allowing a pipeline flange to be buried? I have a 36" pipeline flange carrying hydrocarbon that operations is wanting to have it buried. I believe this is not a good engineering practice but I don't know which code to use to justify myself one way or the other.

From your experiences, is burying a flange a good engineer practice even though it elimnates the need for personnel access and the attendant safety and area classification issues.

Thank you very much in advance as I wait for any responses
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PWSlack
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#1

Re: Buried Flange in Hydrocarbon Service

03/13/2014 3:23 AM

The circumstances will be in the Piping Standard document for the operation. It cannot be seen from here.

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Tornado
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#2

Re: Buried Flange in Hydrocarbon Service

03/13/2014 3:51 AM

Telling anybody might violate the acceptable conditions.

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Whitephone
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#3

Re: Buried Flange in Hydrocarbon Service

03/13/2014 4:26 AM

Are you using API 1104? or what?
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Tornado
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#4
In reply to #3

Re: Buried Flange in Hydrocarbon Service

03/13/2014 4:34 AM

That's a flange?

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Whitephone
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#5
In reply to #4

Re: Buried Flange in Hydrocarbon Service

03/13/2014 4:46 AM


No Tornado, is not a flange. Is a Buried example. The question is: API 1104?. If it is, then is not acceptable the use of buried flanges. I am reviewing the API 1104, but I am sure about this.
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Whitephone
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#6

Re: Buried Flange in Hydrocarbon Service

03/13/2014 5:42 AM

Ok, I was wrong. Is totally acceptable, the best example is the burried Falged valves.

There are many different kinds of Coatings.

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lantulu
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#7
In reply to #6

Re: Buried Flange in Hydrocarbon Service

03/13/2014 6:10 AM

If it is acceptable to use buried flanges as good engineering practice, then what about issues relating to inspection, corrosion, etc? It may be good from a project perspective but the total life cycle cost may be too high. What are your thoughts?
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dolby
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#8

Re: Buried Flange in Hydrocarbon Service

03/13/2014 9:34 AM



http://www.eng-tips.com/viewthread.cfm?qid=241408


http://www.eng-tips.com/viewthread.cfm?qid=350800


http://eng-tips.com/viewthread.cfm?qid=290564
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bigg
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#9

Re: Buried Flange in Hydrocarbon Service

03/13/2014 2:28 PM

I have read the responses and re-read your OP. I gather that this is in a process plant and not a cross-country pipeline. If that is true, I would question the decision to bury the pipe at all, disregarding the flange issues. Why don't you provide more information on this installation?
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lantulu
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#10
In reply to #9

Re: Buried Flange in Hydrocarbon Service

03/13/2014 8:08 PM

Bigg: you are partially correct. These are lateral lines from process plants joining cross country lines. In some instances they are cross-over lines from one cross country line to the other. One key feature of the lines is that they cannot be pigged hence inspection is necessary. If buried, they need to be dug up each time there is an inspection. The life cycle cost could be astronomical. Is there any code of practice that forbids burying the flanges or valves if they are in flammable hydrocarbon service?
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old salt
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#11
In reply to #10

Re: Buried Flange in Hydrocarbon Service

03/13/2014 11:57 PM

Put them in concrete subsurface "boxes" (vaults) with ground level access from a man-hole cover. If access is needed for inspection simply pop the man-hole cover off and go down in the vault on a built-in ladder, using proper confined space entry procedures of course!

Make the top surface of the vault removable so if removal of the valve or large repair tools are needed only a little dirt needs to be removed. Lift the top with a crane or fork lift and you have full access. Make the box large enough that mechanics can use their tools without obstructions such as side walls, ladders, mechanical devices, etc.

If flammables are in the pipes/valves install a pipe with a cap from above ground in the cover to within the vault and LEL tests can be taken without entry. Install another one on the opposite side of the cover and the vault can be purged by forcing air in one and venting vapors through the other pipe.

Good Luck, Old Salt

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lantulu
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#12
In reply to #11

Re: Buried Flange in Hydrocarbon Service

03/14/2014 5:31 AM

Old Salt,

Wow! Old Salt indeed. Thanks a lot for the wonderful recommendation. I will go with this one. Does this come back experience or is there any code to follow?
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old salt
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#13
In reply to #12

Re: Buried Flange in Hydrocarbon Service

03/14/2014 11:54 AM

dtemang-

Past experience. Part borrowing from other systems with the same problem, part laziness, part tired of seeing personnel doing the same thing over and over again, part personnel safety, part looking at future costs and finally if it has to be dug up each time it won't be checked as often as if it was more accessible. Experience is the best teacher.

No insult intended towards anyone in particular but many code writers are dreamers that have very little or no practical experience in the field that they are writing codes for. Many have incredibly great looking resumes but little or nothing to realistically contribute.

Good Luck, Old Salt

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bigg
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#14
In reply to #12

Re: Buried Flange in Hydrocarbon Service

03/15/2014 8:21 PM

Added my GA for OldSalt. Good solution if you must put it sub-grade. I still don't understand why it must be underground (it must come aboveground somewhere), but that's not important. I would just add that you should consider the possibility of ground water ingress and removal, and I would consider a permanent positive vent on this box.
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