Dear Sir,

While designing One of tubesheet having large pitch. This causes ligament efficiency more than 0.6. As such UHX-11.3 figure is limited to 0.6.

As such in my opinion if ligament eff. is more Tubesheet should be more safe. Is there any method by which we can check?

Or shall we input Efficiency 0.6 & calculate.

PVElite gives error" Calculation Terminated."

Pl guide.

Rajesh Bhavsar

Hi BhavsarRC

We have no information other than that found in section UHX. You could very well be correct, but we do not have any other source from which we can get information about large ligaments.

Rajesh,

As Ray pointed out that Div. 1 UHX does not have information for eff. ligament (mu*) more than 0.6. But, the Div. 2 code provides special curves that can be used for mu* up to 1.

So, we added these mu* extension curves in later build for PV Elite 2009. We also print a note when this happens.

Either use PV Elite 2010 (or a later version) or if you have to use the 2009 version send us an email we can direct you the build for PV Elite 2009.

But, if you are using a version of PV Elite older than 2009 then you are out of luck, in that case upgrade to 2009 or 2010 versions.

Thanks Mandeep,

Useful information.

Regards

Rajesh

You may wish to consult with your AI about using ligament efficiencies from Div 2 tables for a Div 1 vessel (I am not sure there is an interpretation that allows this per Code). I have encountered this problem as well in designing scabbard type exchangers. The solution to resolve this with our AI was to also also run the TEMA tubesheet calculations and show that the design is satisfied by both methods.

This is not a bad idea.

I think if the extension curves are in Div. 2 they can be in Div. 1 as well. I will forward that to some people on the concerned ASME committee.

Thanks, Mandeep & D naukam,