vertical load check of bare piping on beams 1

[socrate1980]

good day to everybody

anybody can suggest me where can i find verifications for bare piping resting directly on beams or rod bar welded along centerline of top flange beam to concentrate load.

the verification should tell me if he vertical load is not high for bare pipe or it is needed reinforcing pad to increase local thickness.

thank you very much

socrate

 

[C2it]

Have a look at Roark.

Resting pipe on a rod bar or re-bar is always a bad idea.

 

[socrate1980]

ok thank you for the suggestion.

anyway there is some standard or code where can i find the verification i am talking about?

why is it bad idea pipe resting on bar?

thank you socrate

 

[C2it]

There is no Code or Standard that I am aware of governing resting type support loads.

A pipe wall resting on a small diameter rod is an outdated support idea based on a misconception. In truth, there is a theorectically infinite stress at the contact point, which is clearly poor engineering.

 

[DSB123]

As C2it says it is a bad idea to have a point contact. The Hertz stresses are infinite and in reality there is some degree of indentation (dependant on which is the weaker material pipe/rod) to reduce the stress levels due to the load. There is an indentation check which some companies use. It is far better to use a section of flat bar since the contact will be over the width of the flat bar as a line load. Again the stresses (bending) are high and need to be checked in combination with the pressure stresses.

 

[nipra03]

This issue of local stress analysis is not really addressed by the codes i.e. in terms of calculation formulae. A piping stress manual/text e.g. PENG and PENG will provide for working guidedlines.

 

[StoneCold]

I have been seeing a lot of I-rod supports on bare pipe recently. Especially if the pipe is greater than 4" in diameter.
The smaller piping I have see is just resting on the I-beam support.

Regards
StoneCold

 

[Greg80]

It's not a good practice to install piping directly on rod bars, however you may weld a plate to your rod bars and install your piping on it.
Ensure that your piping will not fall down from the rod bar... so you can drill 2 holes in the plates to install a U-bolt.
Finally, ensure that your rod bars can take your piping loads

 

[RoboCop16]

Not that I necessarily agree on supporting piping on rod bars. But the idea behind it is to reduce the area between the pipe and the support where moisture can get trapped and lead to crevice corrosion. That idea has some merit. In many environments, loss of integrity due to corrosion is a more real concern than any local stress issues due to the point load.

In the offshore oil & gas company that I work for, we will not allow metal-to-metal contact at all between the pipe and the support and always have an elastomeric pad between the two. I-rods seems a good solution as they minimise the crevice area and do not have -metal-to-metal contact.

 

[C2it]

Exactly what is and I-rod then ? I assumed you meant a metal rod.

 

[LittleInch]

These things

http://stoprust.com/i-rod-pipe-supports/

Basically plastic rubbing bars, but built to take the load.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[socrate1980]

thank you

but i am concerned about the pipe... not the support. i what to answer to question:

given a bare pipe load... do i need reinforcing plate there? i want to know the formulas!

 

[LittleInch]

socrate,

C2it, DSB123 and Nipra03 have all answered this point which is that there are no formulas for this.

"Historical engineering" shows that if you keep within normally recognised span lengths for the different sized pipe then you will be ok. If the pipe moves a lot, both for distance and frequency of movements then you might need a plate on the pipe to account for loss of metal as it scrapes back and forward, but otherwise no.

As noted above, this type of support is now not normally used and a shoe arrangement (bolted or welded)is now much more common.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[PaperEngr]

Here's one reason not to rest bare pipe on round bar. See attached below.

 

[robyengIT]

here some tables from "Structural analysis of buried pipes" by Hornung/Kittel
Regards

 

[hacksaw]

There is a lot more to piping than formulas...listen up to what you are being advised