(No subject)

In the Power Piping Code, B31.1 para. 101.7.2 does not direct the design of metallic bellows expansion joints to be in accordance with an Appendix or any industry standard, and so it does not specifically address fatigue design of the bellows elements. (The Process Piping Code, B31.3 para. 304.7.4 directs the design of metallic bellows expansion joints be in accordance with Appendix X, which gives specific requirements for the fatigue design, but does not give a minimum cycle life.)

B31.1 para 102.3, Allowable Stress Values and Other Stress Limits for Piping Components, gives a stress range reduction factor of 1.0 for 7,000 full temperature cycles or less.

For a expansion joint specification requiring compliance with B31.1:

Mfg. P stated: "There is no minimum life cycle specified in any of the design codes. ...1000 cycles is our current standard...." Mfg. H stated: "ASME suggests a life cycle of 408 cycles, however, Mfg H,a member of EJMA which requires 1032 Cycles."

Many may know this already, but for those that rarely spec expansion joints, I hope this thread shows that it is important to pin down the cycle requirements because the Codes do not. It happened this time that we got nearly equal design basis on cycles, but for different reasons.

Ken A. Nisly-Nagele, P.E.

Project Engineer, Mechanical

Applied Engineering Services

9100 Keystone Crossing, STE 200

Indianapolis, IN 46240

Office: 317.810.4141

<a href="/group/PipingDesign/post?postID=PpX5OTkuI5UZPb-gFb-iMU8d3dDggRbSvP0arASSlccNJqWZeMO6F4-iZ7B9Ap1afH1_-rLaQhxGcOkeqWRnTPMerA">knislynagele@applied-e-s.com</a>

[Non-text portions of this message have been removed] Received on Wed Sep 26 12:14:00 2007