Torque for M24 SS 316 HCS w/ anti-seize? 1

[sprintcar]

Need torque value (ft-lbs) for type 316 stainless M24 bolt / nut joint, at 60% yield with anti-seize on threads.

Assumed fastener yield at 50ksi thus 30ksi when tight. Tensile area is 352.5mm^2

Oiled value came out to 276ft-lb (using 1" bolt)

NASA spec for 316 with dry lube is 155ft-lb, but I believe they use the K value for moly in that

I'm still searching for my reference charts, so any help would be appreciated!



"If A equals success, then the formula is: A = X + Y + Z, X is work. Y is play. Z is keep your mouth shut."
-- by Albert Einstein

 

[CoryPad]

faq725-536

Friction coefficient for austenitic stainless steels (according to VDI 2230):

0.08 to 0.16 when lubricated with "solid lubricants or waxes; pastes"

0.14 to 0.24 when lubricated with "wax dispersions, pastes"


Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Screwman]

Cory,
Are those friction coefficients or nut factors? I don't have my VDI copy by me so I can't look it up. If those are not factors they seem pretty low for SS on SS, even if it is lubed. Given the diameter I am guessing that both components wil have cut threads,which can tend to bump the nut factor unless done well.

I don't have data in this size range though, so I can't help much.

Dick

 

[CoryPad]

Dick,

Those are friction coefficients, not nut factors.

I think those are accurate for rolled threads and MoS₂-based lubricants.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Fabrico]

Torque specs are not an exact science. If it's so critical, why not do some stretch checking.

 

[Tmoose]

One of the anti-seize mfrs had fairly comprehensive torqe results for some fasteners. I could not find the link

 

[sprintcar]

Glad to see I wasn't the only one who couldn't find all the ref material.
Took a swag based on a few calculations and used 220ftlb for the instruction sheet. Not critical enough to warrant stretch measurements but should be adequate for the application.
Thanks!

"If A equals success, then the formula is: A = X + Y + Z, X is work. Y is play. Z is keep your mouth shut."
-- by Albert Einstein