ASME B31.8, weldolets for nozzles

[mechaus]

Hi All,

Designing a pig launcher 900# rated. Design code B31.8. Materials Main run pipes are API 5L X52, Weldolets A694 F52.

For all nozzle connections (upto 4" NPS) customer wants us to use weldolets with weld neck flanges weld directly to weldolets. The issue I have is how to check whether the external nozzle loads customer has specified can be accommodated by these nozzles. We normally use PVElite to calculate/checking the maximum allowable external nozzles loads for pressure vessel applications. Trying to find out whether we can model these nozzles in PV elite rathher than setting up a new spread sheet.

The issues we are facing are as follows:

1. Cross sectional thickness of weldolets are not available from anywhere. Therefore the nozzles can not be modeled with say equivalent thickness.

Has any one come across this situation before and found a solution?

Any input will be highly appreciated.

Regards
mechaus

 

[LittleInch]

Pig traps are not pressure vessels so should not be analysed as such, which as your design code is 31.8 you seem to have accepted this.

They are simply bits of pipe so you need to use a pipe stress program which should have weldolets available as an input.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Duwe6]

A weld-neck flange welded directly to an O-let is MASSIVELY STRONG and stiff. Calc the pipe at the edge of the O-let and ignore the flange-O-let assembly. And yes, it's just pipe.

 

[mechaus]

Thank you LittleInch and Duwe6 for your helpful comments. Appreciate it.

We are tossing up the idea whether to buy a pipe stress analysis software ( we have an engineer who use to do pipe stress analysis using CAESAR II)or outsource the pipe stress analaysis to a consulting company.

Buying Caesar II just for one job will be overkill as we do not know when we will use it again. Are there any other software that any of Eng_tips members have used which can do a pipe stress anaysis like this not as expensive as Caesar II?

Thanks in advance

 

[europipe]

I know there are courses in stress analyses so that you can make your calc's by hand.
Furthermore it's very good for your insight in this matter.
Greetings

 

[uaepiping]

@ europipe,

"I know there are courses in stress analyses so that you can make your calc's by hand."

Details of such courses please!

 

[europipe]

I haven't, live in Holland and I know a former collegea did the course a year of three ago, maybe PBNA. Cannot imagine other countries don't have such a course.
Greetings

 

[mechaus]

Thank you europipe. Will look into our options and report back how did we go later. Thanks to all.