Joint efficiency

[vesselpv]

Design pressure is 6500 psig and diameter of cylinder is 3". The top of cylinder is closed with threaded cover. The thickness of cover can be calculated per UG 34 of ASME Div.1. Since material is forged aluminium alloy,only Div.1 can be used.

Threads will be taper pipe threads per Table UG-43. However to calculate the required threaded length, what threaded joint efficiency should be used. Could some one provide some reference.

Thanks!

 

[SnTMan]

You might look at UG-43, also I seem to recall some guidance in Section 1. Sorry I can't be more specific at this time.

Mike

 

[chicopee]

I remember looking at hydraulic jacks and I dont believe that the threaded plates had tapered threads From recollection these threads appeared to be machined fine thread.

 

[PVinspector]

Have you considered U-1(c)(1)(i) vessels having an inside diameter, width, height, or cross section diagonal not exceeding 6 in. with no limitation on length of vessel or pressure.

You are exempt. Or are you stamping as a contract requirement?

ASME: Always-Sometimes-Maybe-Except
PED: Pain Every Day

 

[unclesyd]

We always purchased our smaller reactors. We used numerous reactors of all types and sizes from Parr. They have about anything you want designed to any code or standard.

http://www.parrinst.com/default.cfm?page_id=92

 

[SnTMan]

To revisit briefly, I don't think I'd want to try to seal 6500 psi with a pipe thread. Yeah, you can do it, but it could be messy.

A place I used to work made small vessels for up to 10,000 psi and would use an acme threaded ring bearing on a (non-rotating) plug sealed with an o-ring. You didn't have tighten the plug godawful tight to get a seal.

Regards,

Mike

 

[panduru]

If vesselpv is still listening.

The original question was about if a threaded cover were to be used, what would be the joint efficiency to be used in design?

I'm keen to know, too.

 

[SnTMan]

I don't believe the concept of "joint efficiency" is applicable in this case. UG-34 gives requirements for designing the threaded cover itself per sketch (q), while UG-43 (e) gives requirements for minimum thread engagement. These two requirements seem (without going through the exercise) to be sufficient.

Regards,

Mike

 

[panduru]

Thank you, SnTMan.

 

[vesselpv]

SnTman/ PV Inspector

The cylinder is being designed per ASME Section VIII Div. 1 with threaded cover per UG-34 and threaded length per Tbale UG-43. Threade are being used pipe taper threads with 'O" ring for sealing. Vessel will be registered as Fitting per CSA B51.

Thanks everyone for input