Clamp-On Shoes as Anchors

[DGrayPPD]

I would like some clarification on clamp-on pipe shoes. A suggestion has been made to use clamp-on type shoes in lieu of welded shoes due to the client requesting as minimal welded pipe supports as possible. There are some areas where the pipe shoes would need to be used as anchors. My basic research has told me that clamp-on type shoes should not be used as anchors.

The line information is:

NPS - 2"
Commodity - Hot Oil
Mat'l - A106 Gr. B
Oper. Temp. - 356 deg. F
Oper. Press. - 50 psig
Max. Temp. - 400 deg. F
Max. Press. - 100 psig
Des. Temp. - 460 deg. F
Des. Press. - 150 psig
Insulation - 1" Pyrogel XT, Aluminum Cover

Is there cause for concern with using a clamp-on pipe shoe in this situation as an anchor? And should clamp-on shoes never be used as anchors?

Thanks

 

[TGS4]

Clamp on shoes ought not to be used as anchors. However, with the small addition of welded-on retaining clips to the pipe, the clamp-on shoes can adequately function as anchors.

 

[mk3223]

I think the "anchor" as mentioned is talking about the "axial" direction of support. The clamp-on shoe support is bolted on the pipe, so it's questionable to be a true restrain on the axial direction of the pipe.

 

[pennpiper]

DGrayPPD,
Please explain to us why your project is placing 2" NPS Pipe on Shoes.
Normally, I don't think it is done.

Sometimes its possible to do all the right things and still get bad results

 

[DGrayPPD]

Pennpiper,

The shoes are just simply to protect the insulation. In your experience, is it uncommon to use shoes for insulated pipe even on 2" piping?

 

[TGS4]

mk3223 - I know exactly what the OP meant. I have used them on many projects. Hence the need for "clips" (think 1"x1" or smaller) metal welded to the pipe to permit the transmission of axial loads to the clamp.

 

[DGrayPPD]

Alright, well after further reviewing everything it has been determined that welded shoes can be used instead of clamp on.

However now the suggestion is to weld the shoe to the top of the pipe and drill 4 slotted holes in the base of the shoe in order to bolt the shoe to the underside of a beam that is directly above it and to allow axial movement of the shoe. This still seems like a bizarre way to support the pipe to me.

Does anyone else find this to be another odd suggestion? And just so we're clear, I am not the designer. This is a colleagues design that I am simply seeking advice on before I begin to check his design, and maybe offer alternative suggestions.

Thanks again.

 

[BigInch]

Basically you should not use anchors. Always use the fewest possible. You want plenty of flexibility in any hot line. The question is, why do you need to anchor it?

Since clamps theoretically can provide more flexibility than a full welded anchor, clamps are typically more beneficial to the pipe than is an anchor, as stresses will be that much lower. Clamps, if designed strong enough, can be assumed to be anchors, if the pipe system has sufficient flexibility. Two clamps holding a straight, short pipe between them would not provide enough flexibility and the clamps would probably slip. With the addition of a few changes of direction with a couple of 90deg elbows and it's an entirely different story. It's the relative regidity of the clamp compared to the regidity of the pipe configuration it is holding that matters.

A 2" pipe configuration isn't very difficult to make flexible. It is very flexible anyway, even without expansion loops. A 90 or two and you're home. What's with the slots? Why is no lateral movement of a 2" pipe allowed. Surely a small amount can be accommodated. Why not a simple hanger from the beam?

My opinion here is, if you need slots or anchors on a 2" pipe, I think that the configuration is probably very poorly designed. Something feels very, very wrong. Lack of flexibility, or could it be just ... inexperience in pipe layouts.

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[DGrayPPD]

Thanks BigInch,

I will post a picture in the morning of the suggested support to give better visualization.

 

[DGrayPPD]

Alright, good morning to everyone. I have attached a picture of the suggested support that I have in question.

If you all would be so kind as to give me your thoughts and any advice, I would appreciate it. And to follow up to BigInch's question, I am not positive that the pipe cannot move laterally, this support would just allow axial only.

I have been trying to research as much as possible, but I just cannot find a clear answer on if it is okay to bolt a hanging type support to the structural beam like what is shown in the picture.

 

[BigInch]

You worry too much. I'd just use a clamp-on and get on with business. As I said, it's better than having an anchor that you don't need anyway.

It is OK to use a hanger. I don't think it would be too long in this case. Except maybe here you don't have enough room between beam and pipe. Can you lower the pipe a bit?

Bolting shoes to the bottom of a beam is a bit unconventional, but there's no laws against it. You don't get the benefit of all the bearing surface of the shoe when it's upside down. Why use a shoe? A clipon clamp would work much better.

Slotted shoes need a double nut for jambing purposes to eliminate excess friction or to keep the nut from turning off the bolt. Washers wouldn't be unusual either.


Technology is stealing American jobs. Stop H1-Bs for robots.

 

[DGrayPPD]

Thanks BI. Those are more the answers I was looking for. I appreciate you taking the time.

 

[BigInch]

Devil is in the details.

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[mk3223]

Make sure there is enough head room for drilling machine and space on the steel beams flanges for the bolt holes. For a tight bolt-up on the structure flange, it may need to have a tapered washer for bolting.

 

[BigInch]

And that they slot the shoe, not the beam.

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[DSB123]

pennpiper,
So if you had a 2"nb Steam line how would you propose to support it if not on pipe shoes. Or perhaps what about a 2"nb hot oil line as the OP noted?? Love to hear how you would support hot of in fact cold lines if not on shoes??

 

[KevinNZ]

I would not agree with all the above. My take is

[ul]
[li]Insulated and lines that move a lot need slippers[/li]
[li]Anchors are required in areas than need seismic design. But still allow for thermal expansion[/li]
[li]A clamp shoe can be anchor when tight and not in vibration service.[/li]
[/ul]

 

[BigInch]

#1 is good. Others, to be universally acceptable" need a lot of cavets mentioned above.

For example, "How tight is tight?" and it isn't exactly clear how an anchor allows thermal expansion, because discussing an anchor in the context of somewhere allowing moving pipe somewhere else defeats the value of the anchor to that segment of pipe. Then again guides are selective directional anchors that would allow movement in one direction and yet stop both thermal and [pre][/pre]seismic movement in other directions.

Technology is stealing American jobs. Stop visas for robots.