Flange Mounted Pipe Support Requirement? 3

[mleuenbe]

Hi everyone, I know I don't post a lot, but I sure do appreciate all the good information here, and hoping someone can help with this. I know not to bolt a support bracket under the first nut on a flange. If this is necessary, one should order a longer stud, and put the bracket or support plate after the first nut, then torque up a second nut to hold the support. But I can't find a requirement or even a guideline for this anywhere. Does anyone know where this might be written down. Code or Standard requirement would be great, but even if it's just a recommended practice, I'll take it. Just looking for some kind of reference that might have a good explanation I can share with others at my location.

Thanks!

 

[MJCronin]

Like This ?

http://www.standon.net/s89instl.html

http://anchoragegroup.com.au/height-adjustable-pipe-support-flange-mount/

http://www.gshangers.com/pipesupportdetails.php?supid=174

MJCronin
Sr. Process Engineer

 

[NBrink]

I don't have any references for it, but if you're looking for an explanation to share with others, just ask them what happens if the support has to be removed on the run for whatever reason (leak sealing clamp, running other lines, etc.)

Are they planning on breaking the flange to remove the support?

 

[mleuenbe]

MJCronin, yes, like those, or a custom thing made from plate in my specific case. I've made it a requirement at my facility that this is not allowed for new construction, and for existing installations, we are trying to modify/correct the installations. I'm not getting a lot of pushback (yet), but I generally like to have well documented reasons for the rules I put in place. In my local requirements document, we try to footnote where requirements come from. We've found it really helps, not only to guide the users of the requirements document, but also when I have a "senior moment," and forget why it is we allow/disallow something, it's great to have a footnote reminding us why it's there. We footnote higher level NASA requirements, ASME Code, OSHA, internal Mishap Investigation Board reports, and others.

NBrink, thanks for the excellent observation from the operational point of view, that will help when I need to make the argument for new construction projects.

From a design standpoint, since the bracket most likely will not be through-hardened, and thermal expansion/contraction may put bending stresses on the bracket (and a prybar effect at the nut), uneven loosening of the joint could be the result, leading to leaks, correct?

 

[bimr]

This issue probably fails under good engineering practice.

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1. If you are installing new pipe supports, it is not possible to locate the support pier and foundation until the flange locations are precisely located.

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2. Flange supports are rigid and do not allow for pipe thermal expansion.

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3. Maintenance issues are inherent since the pipe must be shut down to work on the flange mounted support piers. You have to unbolt the support to break the flange.

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4. Flange mounted pipe supports increase the pipe stress at the flanges.

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5. No one has evaluated the structural combination of the pipe flange, bolts, mounting clip, and pipe support because the combination is a bad idea.

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6. Requires an additional set of flange when you want to add the flange support.

DIPRA has recommendations on pipe supports. It is for ductile iron pipe, but the same issues are present.

http://www.psig.sg/Don/B31.3 Process Piping Course - 07 Layout and Support.pdf

 

[Gator]

I recall seeing this type of support in refineries used as a temporary solution (which then becomes permanent because fixing it becomes low priority). It's not an equipment nozzle connection, I trust.

Piping Design Central

 

[NBrink]

Hey, that's a heck of a lot nicer temporary solution than the stacks of slugging wrenches and scaffold boards you run across every once in a while.


They're really not an ideal support since you've got to add additional temporary supports to break the flange, but you can do a lot worse. Not sure I buy the thought of a pry-bar effect on the flange. Even a small (3/4" say) B7 stud will easily be carrying what? 15-20 kips when the flange is made up. A little piece of sheet metal in there under a couple of nuts isn't spreading the flange.

 

[europipe]

Gator, worked with alot of Petro-chemical companies, but most of them have these supports in their standardsupporting book for permanent solution.

 

[mleuenbe]

NBrink, you're probably right about the pry-bar effect not being credible, me over-thinking it a little. Many of the brackets I've seen here tend to be thicker plate.

Thanks everyone for your comments. Sounds like there is no known Standard, Code, or Recommended Practice covering this installation detail. If I do end up finding something, I'll post it....

 

[Gator]

europipe, yes I've seen them in various pipe supports standards details, but I can't remember one being specified for a greenfield project or even brown. But, that's just my experience.

Piping Design Central