Bolt Torque to Pressure 3

[myname_earl]

I have a scenario of installing a circumferential clamp on a 12.75" OD pipe. I calculated that the max allowable external pressure is ~45 psi from ASME BPVC VIII UG-27.

The 2 bolts will be torqued to 30 ft lbs. How do I calculate the pressure the clamp will put on the pipe due to it being torqued?

The (SA-516 Gr 70) 12.875" OD clamp is 1.25" wide, with two 5/8-11 UNC Studs (SA-193 Gr B7) used to tighten against the pipe.

Mechanical Integrity Specialist (Year 1)

 

[desertfox]

Hi Earl

A very rough calculation based on the info you have posted:-

Surface area of half clamp roughly 25.28 sq inch from (12.875 x pi/2) x 1.25

Tension from torque on stud 2851 lbf

Two studs therefor 5702 lbf

Pressure 5702/25,28 = 225.5 psi

The clamp has grooves machined within it which means the area of the clamp in my calculation is higher than what it should be.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[IRstuff]

Didn't understand why the cantilever until I saw this; the pipe behind the tank actually touches the tank on the side opposite the 1" pipe in question

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[myname_earl]

Thank you for answering my question desertfox! I will give it a no-go.

Mechanical Integrity Specialist (Year 1)

 

[LittleInch]

So you chop the 1" pipe off before you place that sealing pad over it? So 50 psi steam jetting out of your 1" hole?

With that clamp structure connected beforehand I guess. Then fit something in the hole in the clamp?

Still looks too high risk to me and only a 5mm thick 24" piece of pipe to boot.

There is a significant risk that you will collapse the 24" pipe or "crimp" it when you tighten up those clamp bolts as you first described.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[desertfox]

Hi Earl

You’re very welcome.
I also have concerns about the corrosion etc but others. Are giving you good advice on that.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[rb1957]

would be unacceptable to tighten the bolts to 6 ft.lbs ? (20% torque = 20% pressure = 45psi)
or maybe 3 ft.lbs ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[CWB1]

How do I calculate the pressure the clamp will put on the pipe due to it being torqued?

You don't, the supplier provides test data showing the boundary conditions under which their product functions. You verify the boundary conditions.