support shoes or saddles

[Zapster]

I have seen several different means to attach pipe supports to the pipe. Obviously any attachment method should be evaluated to ensure that the combined allowable yield stress is not exceeded. So for ASME code piping, B31.8, B31.4, B31.3, and B31.1 are there restrictions other than code stress that addresses whether a T shoe can be directly welded to the pipe or whether a 120 deg saddle is required or full encirclement reinforcement is used, etc. At discussion here is a lightly loaded T shoe on a small bore pipe, if it were directly welded to the line pipe, and allowable stress would not be exceeded. Are there any code restrictions for welding a shoe directly to a mild steel pipe A53/A106/API5L? What are the common practices for the different codes or does it break down more along different industries?

 

[C2it]

You need to read the codes. B31.4 for example does require full encirclement plates under some circumstances.

There is normally no restriction to welding a shoe to mild steel.

It is good to avoid welding shoes if possible, to avoid site errors with support locations, and a nasty up-hand weld if done in situ. You could think about clamped shoes unless horizontal restraint (e.g guide / stop) is needed.

 

[MJCronin]

Anvil provides pipe shoes for your use:

http://www.anvilintl.com/Literature/Catalogs.aspx

Lisega (GDR) supplies both clamp-on and weld-on saddles:

http://www.lisega.de/

Investigate these standard products and call the vendor if necessary.....

Report back to us, if you please, with your results

 

[BigInch]

Do not weld directly to pipeline pipes designed under B31.4 and B31.8


We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[Zapster]

Per B31.4 404.91, if line is operated above 20% SMYS then support must be attached to full encirclement reinforcement.

Per B31.8 834.5 if hoop stress is greater than 50% then support must be welded to full encirclement reinforcement.

I understand that it might be frowned upon in certain industries especially above grade segments of B31.4 and B31.8 piping systems that may use heaver wall pipe than the line-pipe, but do contractors weld shoes directly to these piping systems when they can? Or is it just frowned upon even when the requirements of B31.4 or B31.8 are met.

Are some of these attitudes carried over to B31.3 piping where it too may be frowned upon even though it may meet the letter of the code.

I would like to hear from some of the professional pipers as to when they do use shoes welded directly to the pipe without reinforcement, and what industries served are open to this?

 

[BigInch]

It is prohibited for pipelines and if a contractor did it, he'd be rebuilding it at his own expense. A greater percentage of yield stress is reserved exclusively for hoop stress utilization, so no introduction of additional stresses by rigid-welded-to-the-pipe restraints is welcome.

You can use shoes on non-pipeline code work, when the stresses from axial, shear and bending loads are less than allowables. A full encirclement detail will typically distribute the stresses more evenly around the whole circumference thereby eliminating localized stress intensifications.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky