Stress Analysis Criteria (What to analyze) 1

[famm]

Hello Guys,

I've got to design a cold water system for a refinery as per ASME B31.3 (fluid is sea water @ 85ºF, and pipe is cement lined), that has pipes from 8" to 60", and I can´t find a table that says what I have to analyze.
I read that as per "Design of Piping Systems" (Kellogg), with this conditions (temperature and sizes) I might have to analyze with a software only pipes over 48", and the rest of the pipes by manual method. Is that right?

 

[richay]

Check this thread [URL unfurl="true"]http://www.coade.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=9349&page=1#Post9349[/url] on the COADE Discussion Forum.

Richard Ay
COADE, Inc.

 

[NozzleTwister]

Each company normally has their own criteria about what lines they what reviewed by a Piping Engineer and which lines from the first group the want to see a formal computer analysis.

For those lines that aren't required to have a computer analysis, it's normally up to the Piping Engineer to perform the level of analysis (inspection, hand calcs or computer analysis)he/she thinks is required to insure a safe piping design that meets the code requirements and also to provide support load information as required to the structural folks.

Most criteria that I have seen requires Piping Engineering review for liquid lines above 12"-14" or so. This is when support loads start becoming significant. Consider the following.
1) Cement lining will add weight to and increase the stiffness of your pipe
2) Check with pipe lining vendor for any design requirements he may impose and the physical properties of the lining system.
3) Evaluate load bearing and local stresses on pipe wall at support location for the larger lines.
4) Control pipe as required for any seismic or wind criteria
5) Question whether the 85 deg. F. is adequate for flexibility and thermal growth requirements. While 85 deg. F. may be a maximum for the sea water source, a non-flowing line may heat up to 150 deg. F. or more sitting in the sun.
6) Provide all loads as require to your Support Designer/ Structural Engineer. (Friction, wind, seismic as required in addition to dead weight)


NozzleTwister
Houston, Texas