BPVC Sect VIII, vessel with custom machined plug

[Bernoulli31]

I'm new at pressure vessels calculations and here's hoping someone would share his/her insights. I have a thin walled cylindrical vessel (25" x 6"), for which the customer has designed a new castellated plug. See attached rough sketch. I'm wondering what type of reactions and stresses can be expected at the nuts, given a certain pressure in the vessel. I would expect the cylinder to expand in both directions, causing a moment in the area of the nut, correct?

I design aqueducts in a parallel universe.

 

[SnTMan]

No offense, but nobody can make heads or tails or your post...

...thin-walled (25" x 6")... Means what?

...castellated plugs... ...nuts... Means what, exactly?

Cylinder expanding in both directions is likely correct but would be kind of a secondary effect most likely, unless it is perhaps REALLY thin-walled.

Sec VIII, OK, but which division? 1? 2? 3?

Regards,

Mike


The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Bernoulli31]

No offense taken. Sorry, I wanted to get this out on the fly, heading into the weekend..

Cylinder is 25" long with an ID of 6". Thickness is 0.5".

I didn't come up with those terms. The customer (machinist) manufactured a custom made plug for this cylinder, think of a cam lock system: insert the plug, rotate until it locks in the cylinder.

Ultimately, an FEA will be performed, so we're talking Div 2. But for now I want to understand what will happen from a stress point of view.

Thanks for your reply!

I design aqueducts in a parallel universe.

 

[SnTMan]

Bernoulli31, so this is similar to so-called breech lock closures used in high pressure vessels. Nothing really new here.

I'd just start with s strength of materials approach, look at shear and perhaps bending of the lugs and so forth, you could calculate expansion of the cylinder in the hoop direction and find it is negligible, or not.

Not familiar with Div 2 to know, but Div 1 has rules applying to "quick-acting closures" which your design could fall under. Nothing to fool around with, as you do not want the plug to exit the cylinder under pressure.

Regards,

Mike





The problem with sloppy work is that the supply FAR EXCEEDS the demand