B31.3 - 2008 Now Available 4

[JohnBreen]

The ASME B31 Code for Pressure Piping, B31.3 Process Piping - 2008 is now available. Date of issuance - December 31, 2008. This Code will become effective 6 months after the date of issuance. There will be no addenda issue for this edition. The next edition of this Code is scheduled for publication in 2010. Yes, I know it is 2009. I hate when that happens.

Regards, John.

 

[jte]

John-

Thanks for the update! Frustrating to get the new edition out late, but at least B31.3 beat PCC-2 out the door, and with a 2008 nominal issuance date. The 2008 edition of PCC-2 has a nominal issuance date of March 19 2009... Anyone taking bets on when it actually gets published?

jt

 

[BigInch]

As someone once said, "Thanks for that copy of your new book. I certainly won't waste any time reading it."
Kidding JB. Thanks for the hard work that went into it.
I do like that quote though.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

CORRECTION
"I certainly won't waste any" => "I shall waste no"

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[DSB123]

JohnBreen,
Are there any significant changes in the new Code. I ask from an interest point of view as I do not have access to the latest version being one of the casualties of the work downturn in the UK.

 

[gatossi]

It would be nice if somebody can list briefly the changes introduced on the 2008 revision.

 

[JohnBreen]

Hello,

There is a summary of changes (4 and 1/2 pages) in B31.3-2008 from page xix to page xxiii.

John

 

[sathish5973]

john,
could u send me the link of asme b31.3 & b31.4 2008 edition...thanks in advance..

 

[JLSeagull]

http://www.asme.org/Codes/

 

[moltenmetal]

One major change is the TESTING SECTION- read it and weep...we certainly did!

 

[StressGuy]

Anything in particular that we should be looking for, moltenmetal?

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[moltenmetal]

StressGuy: I am far from a code expert so please examine what I say carefully and make sure I have not mis-spoken!

Previous versions of the code were similar to the requirements of ASME VIII div 1 for pressure vessels: hydrotesting was carried out at 1.5 (rather than 1.3 for section VIII) times the design pressure times the LOWEST ratio of stresses for materials at the test versus the design temperature. We have in past included the flange bolting in that consideration (to avoid yielding them), whose materials seldom had a ratio of stresses much greater than 1 except at very high temperatures, but that's a bit of a gray area.



The NEW revision of the code states as follows (quoted with added paraphrasing below):



345.4.2 Test Pressure Except as provided in para. 345.4.3 (MM note: this para regards testing of piping connected to a pressure vessel where disconnection therefrom is “impractical”), the hydrostatic test pressure at any point in a metallic piping system shall be as follows:



a) not less than 1.5 times the design pressure



b) when the design temperature is greater than the test temperature, the minimum test pressure, at the point under consideration, shall be calculated by equ. (24) . When the piping system contains more than one material or more than one design temperature, eq. (24) shall be used for every combination, excluding pipe supporting elements and bolting, and the maximum calculated value of Pt is the minimum test gauge pressure.



PT = 1.5 PRr (eq 24)



Where

P = internal design gage pressure

PT = minimum test gage pressure

Rr = ratio of ST/S for pipe or components without established ratings, but shall not exceed 6.5

= ratio of the component pressure rating at the test temperature to the component pressure rating at the component design temperature for components with established ratings, but shall not exceed 6.5

S = allowable stress value at component design temperature (see Table A-1)

ST = allowable stress value at test temperature



Alternatively, for carbon steel piping with a minimum specified yield strength not greater than 42 ksi (290 MPa), the test pressure for the assembly of components, excluding pipe supporting elements and bolting (i.e. pipe, fittings, valves, flanges) may be based on Rr for any of the components in the assembly



c) if the test pressure as defined above would produce a nominal pressure stress or longitudinal stress in excess of the yield strength at test temperature or a pressure more than 1.5 times the component rating at the test temperature, the test pressure may be reduced to the maximum pressure that will not exceed the lesser of the yield strength or 1.5 times the component ratings at test temperature. (see paras. 302.3.2(e) and (f)). For metallic bellows expansion joints, see Appendix X, para X302.2.3(a)



(end quote)

We'll be relying on c) a lot more in future!

 

[rneill]

That clause jumped out at me as well. It has been standard practice to calculate the hydrotest pressure based on the allowable stress values of the pipe and ignore the component ratings of the ASME B16.5 flanges and B16.34 valves but now B31.3 makes clear that you must consider the derating of these components as well when determining the hydrotest pressure.

This is how I've always done it and I've had a few battles with clients and contractors but now the code backs me up. Since our pipe is usually heavier than strictly necessary (schedules are few and far between), it rarely if ever becomes a limitation to the hydrotest pressure determined in this way.

This said, the exemption for materials less than 42 ksi does still provide an out for typical carbon steel piping systems (A106 / A333) and allow you to do it the old way.