×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Decrease the Height of Hex Nut
2

Decrease the Height of Hex Nut

Decrease the Height of Hex Nut

(OP)
During installation of a SS control valve it was found that the hex nut is in contact with the body of the control valve. This happened because an insulating gasket (i.e. dissimilar material and raw water service) is used in the flanged connection; thereby, it increased the bolt length causing the hex nut to clash with valve body. Now, is it possible to decrease the height of the hex nut (i.e. by grinding or machining, for example)? Does the industry code/standards allow this practice?  

RE: Decrease the Height of Hex Nut

What pressure service?
What temperature?
What dia valve?
What industry and to what reg's are you going to (try to) work at?

RE: Decrease the Height of Hex Nut

(OP)
Water service x 630 psig/205 deg F x 8" dia. x ASME B31.4.

 

RE: Decrease the Height of Hex Nut

Under ASME, "if you can engineer it, you can build it" meaning that you would have to calculate the reduced strength of the flanged joint and compare it to the relief pressure, and the impulse generated when your PRV 'kicks'.  At 630 psig, thrust from a PRV is not insignificant.

Also, just use a thinner insulating washer.  A thick micarta washer with a steel washer on top is not your only choice.  If you don't mind "hillbillying" it, cut some plastic washers from milk jugs.  Verify their installation by testing for [lack of] continuity between the stud and flange.

RE: Decrease the Height of Hex Nut

I'd say that as long as you still have three threads in the nut you are OK.  Generally speaking after more than three threads you reach a point of diminishing returns.

Dan

www.eltronresearch.com
Dan's Blog

RE: Decrease the Height of Hex Nut

I'd say that as long as you still have three threads in the nut you are OK.  Generally speaking after more than three threads you reach a point of diminishing returns.

Dan

www.eltronresearch.com
Dan's Blog

RE: Decrease the Height of Hex Nut

"3 Threads"  'Taint so with piping flanges.  Yes, the math should work out.  But somebody has to do the calc's, and sign them.

RE: Decrease the Height of Hex Nut

(OP)
@ Duwe6: 1.5 mm thk Micarta insulation sheet is available in the storehouse; we are using it to insulate SS piping resting on clamped shoe supports. Can we use the said insulation sheet as substitute to the thick Pikotek washers?    

RE: Decrease the Height of Hex Nut

Absolutely.  Micarta is what we usually get in an Insulating Flange kit.

RE: Decrease the Height of Hex Nut

(OP)
As far as I understand, industry code/standards allows up to one-thread less to consider flange bolt & nut to be fully engaged.

Thank you for all the inputs.

RE: Decrease the Height of Hex Nut

1-thread;  actually no.  What is allowed is 'flush at a minimum' on new work.

The 1-thread minus it the maximum underengagement allowed during an on-stream inspection.  And, yes, this implies that being 1 thread short of full engagement is inconsequential.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources