utilize bolt tension device for 26" Studding Outlets

[Steven23144]

I am working for design a ASME 26" Studding Outlets flange for Reactor, I have question as below:
(1) Is it available to design a Class 900 Studding Outlet R.J. flange for 26" ASME B16.47 series "A" nozzle? due to the connected flange type and high design pressure 87 kg/cm^2G. @ 200℃
(2) To accommodate the big diameter bolt size(2-3/4")for high design pressure, We would like to use hydraulic bolt tensioning device to tighten the bolts during equipment installation.
Do some expert advise me is it suitable for studding bolts ? I am worry hydraulic tension maybe damage thread holes.

 

[GenB]

Having the proper and properly calibrated torque
tool, hydraulic o not you should not have a problem.

 

[Steven23144]

Hi! GenB,
Thanks for your advise

 

[Steven23144]

Hi!
To studding outlet pad flange, the tapped holes are provided for stud thread engagement that had been designed based on UG-44(g). However, the tapped thread connection is different form the regular stud bolts which connected with both nuts. So, what I think the regular torque using for ASME standard flange may not be avaliabe.
Dear Expert, How to calaulate or measure the tighten torque and do not be acting over is my question.

 

[SnTMan]

Steven23144, sounds like your concern is with adequate thread engagement in the studding outlet, no?

Most common design procedures, such as UG-44 will insure a depth of engagement such that the male threaded member fails before the female member. Common depth of engagement (for materials of equal strength) is 1 1/2 x stud diameter. Usually, if this depth is provided no further analysis need be performed.

An excellent procedure is found in Machinerys' Handbook.

Regards,

Mike

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

 

[jte]

I really don't like having to deal with studded outlets, and would certainly recommend avoiding them in new construction.

But if you must, then at lest refer to ASME PCC-2 Article 3.3 Appendix I for some thoughts on avoiding damaged threads.

 

[NBrink]

Friends don't let friends make new equipment with studded nozzles. You inevitably come to a time when you can't get one (or all) of the studs detensioned/detorqued and you end up having to machine a stud out, which is a huge, huge, huge time waste. And then someone messes up the machining, you wipe out the threads, and you're scrambling to find out if you can make a stepped stud work in the middle of a turnaround. Go ahead, ask me how I know...


That said, yeah, you can design them to yield the stud before the female threads. As SNnTMan says, usually 1.5 the diameter will do it. Because of the way the load is distributed across the threads, the first couple of threads end up carrying most of the load, so making them indefinitely deeper doesn't really help things.

 

[r6155]

For 2,75" stud use hydraulic bolt tensioner, not torque. See PCC-1. No problems with threads.

Regards
r6155

 

[jte]

Well, it would seem rude to not ask:

Go ahead, ask me how I know...

So, NBrink, how do you know about the joys of machining out a stud, and I'll presume with a slight offset between the centerline of the machine and the centerline of the stud, and the subsequent calculation of acceptable increased diameter tapped holes to accommodate step studs?

But more seriously, did you find the PCC-2 article dealing with this issue, including step studs, to be useful?

[edit] Oh, and I like the thought in your first sentence:

Friends don't let friends make new equipment with studded nozzles.

 

[NBrink]

Well it's no fun telling the story when you go ahead and spoil the punchline like that.

As far as PCC-2, I mean, it's a decent enough overview of factors to be considered, but past that? Not super helpful... Basically just repeats "whatever you do, it needs to meet the original code" over and over again.

Nathan Brink