Welded Supports to thin wall piping

[FIF99]

Hi,

For adding welded support designs to thin wall piping we specify reinforcing pads on the piping before actually welding the supports to it. I do have some reference tables but:
Does anyone have a reference calculation method showing from which Diameter - wall thickness combination these pads are required?
Is this covered in the ASME B31.3 or the BPV?

Thanks in advance for any help.

Regards.

 

[metengr]

You have several different options;

1. Piping Handbook, Edited by: Nayyar, Mohinder L. © 2000; McGraw-Hill

2. MSS-SP58 (MSS SP58 - PIPE HANGERS & SUPPORTS - MATERIALS, DESIGN & MANUFACTURE).

I don't have access to either of these publications at the moment. I would expect that the Piping Handbook would be your best bet.

 

[MJCronin]

FKE,

This may, or may not help you...but here goes. The following is based on many years of piping/pipe support design for power and process systems.

In my experience, piping systems thinner than schedule 40 are all either schedule 10S or (rarely) schedule 5S.

Scedule 10S "thin walled" piping is commonly specified because the service is corrosive and the piping material is typically expensive. Schedule 10S piping in smaller pipe sizes (<6"NPS) typically has adequate strength to be useful for most of the process chemical system pressures encountered.

Most schedule 10S piping systems in this size range can be routed and supported without the need for pads on supports, although some design firms use them without any real criteria

With liquid filled systems, above about 8"NPS or 10"NPS the local loading are much higher and the support becomes a real concern, especially with liquids that have an SG above 1.0.

I suggest a detailed evaluation of local loadings for a certain class of scgedule 10S piping systems ( above 10"NPS, above say 2500 lbs design load and above 300F service temperature)

With regard to Schedule 5S system, ....well..... we are dealing with something that can only barely be called "pipe" and is better refered to as "foil".......In my opinion, use a pad re-inforcement on all piping supports > 3"NPS. Shedul5S should only be used for low pressure vents and similar service.

With regard to schedule 40 and higher systems, pad reinforcements should only be considered on larger diameter (>8"NPS) all-welded trunion anchors and (sometimes) trunions on elbows. Any other application is probably an overdesign or on a system with too few pipe supports

My opinions, recollections only


MJC