Flexibility Analysis - uniform sized pipe?

[Pipeline1972]

ASME B31.3 par 319.4.1 shows us how to find out if a piping systems needs a formal analysis or not. Piping system should be of uniform size.
My question is: what if there's a branch on a piping system? And what should i do with the equipments (valves..) attached to it? How does they affect the calculation?
I guess those kind of systems do need analysis..

Thanks!

 

[JohnBreen]

Hello,

The paragraph that you cite is one of the oldest in the B31 Pressure Piping Code.

Please realize that that paragraph is valid for a VERY LIMITED set of analyses - maybe one out of 10,000 "real world" piping systems (if that many).

Your guess is correct. If there is a branch, a valve, a support, or virually ANY variation from the description of the system at issue (in the Code) the paragraph cited cannot be applied.

Best regards, John.

 

[DSB123]

JohnBreen,
I agree with you entirely. However there are those out in the Piping Design fraternity who still use this extensively as a check for system flexibility. I know of some so-called senior piping engineers whom have used it to check on flexibility requirements for interplant lines which have guides, supports. Also lines which have branches. It's difficult to know how to prevent such occurances other than remove it from the Code.

 

[JohnBreen]

Hello, DSB123 and all,

Yes I know the cited paragraph is misused. Actually, through the years I have been surprised to learn that MUCH in the B31 Codes are/is being misapplied. People still write specifications that refer to the ASA Piping Codes and address various IPS pipe sizes too. Lets hope that nobody will get hurt.

There is not much that we can do within the Code. People WILL use what they want to use and ignore what they want to ignore. There is still a lot of resistance within the Committee to removing the subject paragraph. Perhaps the next generation of Code writers will see things differently

Regards, John.