Pipe shoes between "concrete support" and pipe. 1

[CORPMEX]

Hi,...I am looking for code saying something about the necesity of having a shoe or metallic protection between a pipe and a concrete beam. Any help will be apreciated. Thanks. CorpMex.

 

[JohnBreen]

Hi CORPMEX,

Codes and standards are not design textbooks. Codes do not take the place of qualified piping engineers. Some Codes however do make some SUGGESTIONS regarding good engineering practice. B31.3, paragraph 321.4 Structural Attachments should be read. Also, B31.3, paragraph 321.4 refers you to Appendix "F" and specifically paragraph F321.4, Wear of Piping at Support Points. You should read these paragraphs and note the use of the word "should" instead of the word "shall".

Regards, John.

 

[CORPMEX]

I appreciate your response and Help John... I Read B31.3, paragraph 321.4 as you told me...it helps a lot. Now, regarding F321.4 I can´t find it in the 1999 edition.. Is it in another Edition?..thanks..

CorpMex.

P.S. Sorry for My Mexican English.

 

[JohnBreen]

Hi CorpMex,

Your English is fine, you are quite understandable.

You must go to B31.3 Appendix "F", "Precautionary Cosiderations" to find paragraph F321.4, Wear of Piping at Support Points.

"F321.4 Wear of Piping at Support Points

The use of pads or other means of pipe attachment at support points should be considered for piping systems subject to wear and pipe wall metal loss from relative movement between the pipe and its supports (e.g., for wave action on offshore production applications)."

Note that the words "should be considered" indicates that the Code makes this non-mandatory.

This same recommendation could apply to situations where the pipe wall is resting directly upon a concrete "sleeper" type support. Thermal expansion/contraction may cause enough movement to cause wear at the point where the pipe wall contacts the support beam. It is common practice at such supports to weld a "doubler plate" (aka "wear pad") to the bottom of the pipe OD and/or to embed a POLISHED bar in the top surface of the concrete "sleeper" (note the bar presents a "POINT of contact" and sometime the pipe weight bearing on the bar is contraindicated - more bearing surface might be needed). Note that the recommendation is for a polished bar - sometimes we see deformed reinforcing bars (meant to reinforce concrete) used as the point of pipe contact and these (since they are purposely made rough) cause unwanted wear at the pipe wall. The pipe resting upon a support beam (of any material) also may create a crevice corrosion issue as water often accumulates at the point of contact between the pipe and the support beam. If there is room for a shoe to be welded (or strapped) to the pipe it is preferred. The pipe shoe is the wear surface and the pressure boundary (pipe wall) is preserved from wear.

Regards, John.

 

[BigInch]

Please use a welded plate or shoe. Concrete adsorbes water and releases it at the worst places. You are almost totally assured to have corrosion issues at any pipe resting directly on concrete or where the pipe forms a crevice contact point.

Doing almost anything is preferrable to doing .

http://virtualpipeline.spaces.msn.com

 

[CORPMEX]

JohnBreen:

Guess What... I just can`t find that section in the Apendix F of B31.3. Page 266 includes F307 Valves, f308 Flanges and Gaskets..then F309, F312 and lo F322. Nothing about F321. I also opened my 2001 addenda and didn´t it either.

Where is it then?

Thanks,.

CorpMex.

 

[C2it]

Try page 237 of the 2004 (current) edition ASME B31.3.

 

[CORPMEX]

Ah ok... That´s why. Thanks C2it.

CorpMex.