Dear sirs,

How much is allowable deflection(due to weight) of pipes in a NGL plant? Could you introduce a book or a spec for more information?

Brad Smith,

Piping systems, by law, are to be designed in accordance with a nationally rcognized code or standard. Two common US piping codes are ASME B31.1 and B31.3

Within these piping standards are rules about piping stress analysis and pipe support design and placement. Location of pipe supports determines the amount of mid-span deflection. There are no special rules about NGL piping deflection versus any other contents.

The acceptable pipe "span" for your systems should have been established by the designer of the systems. Typically, a table of "maximum support spans" are developed for each project by the project staff. Smaller piping systems require shorter spans.

Some steam and condensate piping system require "sloped" piping. This can be confusing to the novice.

Hope that this helps...

Dear Mr. McCronin,

Thank you Mr. McCronin, but there are "general rules" in codes such as B31.3 and B31.1.
Client tabulates allowable span for each project(it mentions in the standard support). But in our project(NGL), I think tabulated allowable spans are not in the safe limit. Thus I need a good reference for convincing client to change table of allowable span. Do you know a good handbook or Spec. about NGL lines?

Brad,
I am not sure I understand what the problem is.
a). Did the Client furnish a set of job specific Pipe Support spacing "Standards" to your company for use on this LNG project?

b) Is the Pipe Support spacing on these "job specific LNG Standards" greater or lesser than the normally accepted Pipe Support Standards used for other types of projects?

c) If the support-to-support spacing is greater, then percentage wise how much greater?

prognosis: Lead or Lag

It is first time that our client works on NGL plant. The client issued a "Standard Pipe supports" doc and sent it for us for following this doc in pipe supporting(only one STD pipe support exists). But I think this "Standard pipe supports" doc shall not be used in NGL plants because its recommended spans are high. For example it has recommended 12m span for 10" pipe.

[bBrad,
Would the 10" line be running by it self or would it be mixed in with many other lines of smaller and larger lines?

If it is a single 10" line running by it self then it might be okay. It could have a deflection of between 1/2" to 3/4" depending on the wall schedule and the type and thickness of insulation.

If there are a number of lines in a Pipe Rack configuration then you need to space the Pipe Supports based on what is economical for all the lines.

prognosis: Lead or Lag