some questions about WRC107

Dear sirs:
When we checked the nozzle loadings of the static equipments,we found the actual nozzle loadings are higher than the allowable laodings given by the client.So we use wrc107 to check
the stress,if the result is pass.Do you think if it is necessay to transmitte the higer loadings to the vendor.
Since I am a piping stress engineer rahther than an equipment engineer,I do not konw the stress catageory of the equipments very clealy.(such as Pm,Pl,Q and so on)Could you give me some advice.and do you think we sholud include the pressure trust when do the elastic analysis of nozzle with wrc107?Why?
Thank you!

You state that the nozzle loads exceed the allowable loadings. Assume you use WRC-107 and prove that the stresses are below the allowables. Do you want to be responsible for the integrity of the system? What happens if it fails? Who will the owner look to first?

(Bear in mind that WRC107 is an imperical approximation, based on a limited number of tests, of what can be computed accurately only by a full finite element analysis.)

Pesonally, I'd rather change the piping layout to reduce the loads. Why tempt fate?

Thank you for your quick reply.
Yes, changing routing is a good way to reduce the nozzle loadings and using FE/pipe is more accurate than using wrc107.But in some situations there is not much room for us to change the routing and the actual loadings has exceeded the allowables only a bit.
You know sometimes the allowables are conservative,if we use WRC-107 and prove that the stresses are below the allowables,we think it is ok,we needn't change the routing.If it fails we will change the routing or informed the vendor about the large nozzle loadings.

And I want to learn more about the WRC107.Who could share some articles about this.

Go to L.C .Peng's website.You will find an excellent article there.

Regards

Thank you

What is the URL of L.C.Peng's website?
thank you.

http://www.pipestress.com/papers/WRC107-297.pdf

But, Richard Ay has rightly pointed out. If we don't own an equipment/design, we can't pass judgement on the suitability of the same for a load exceeding the owner's allowable without the owner's concurrance. WRC-107/297 or NozzlePro calculation can form just a justification to get the equipment owner's approval.

regards

sam

P.S.- Dear IMWORKMAN, Are you not too lazy ? Is it too difficult to search L.C. Peng's website ?

A).Equipment drawing to have max allowable loads
B).Piping to provide configuration/design
C).Stress to ensure (B) acceptable for(A)

If (B) overloads (A) then either change (B)
or have loads approved by vendor.

Do not under any circumstances,increase the nozzle allowables without the vendors approval.

WRC107 is only used as guidline when (A) is not available. (Existing plant)

There are circumstances (especially for openings reinforced by external pads) when the "weakest" component of the shell-nozzle junction is the NOZZLE.

WRC 107 method cannot handle this case since this calculation procedure is dedicated to stress concentration assessment for the shell wall only.

Therefore, when the allowable loads (that would have been specified by the vendor) are not available and the Finite Element Analysis approach (such as FE Pipe) cannot be employed, WRC-297 method is the most suitable analytical approach because the both NOZZLE and SHELL maximum secondary and peak stresses are quantified.

Regards,