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Torque Value for Stainless Metric Nut/Bolt, Please Login/Join 
Too clever by half
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I’m replacing 18-8 stainless hardware securing deck hardware to my sailboat. It will experience some sail handling loads so I need to apply maximum torque, but avoid galling. The bolt is 5 mm coarse thread (I think), but the matching nut seems so small and narrow, I’m questioning the torque value I’m finding. Does 45.1 in/lbs sound right?




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Posts: 10227 | Location: Richmond, VA | Registered: December 11, 2007Reply With QuoteReport This Post
Quit staring at my wife's Butt
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Posts: 5260 | Registered: February 09, 2003Reply With QuoteReport This Post
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Here's a torque chart for 18-8 S/S bolts for the various bolt sizes (as well as 316 and other popular S/S used on boats/yachts). I work with a lot of stainless and never have issues with galling, but always use hand tools with stainless (no impact/cordless drills etc.) You could always put a small dab of anti-seize on it if galling worries you.

https://www.engineersedge.com/...less_steel_13353.htm
 
Posts: 20266 | Registered: June 12, 2005Reply With QuoteReport This Post
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Dry or wet torque?

https://www.fastenal.com/conte...ferrous%20Torque.pdf

If it's a thin nut you're looking at, perhaps a shear nut; is the bolt holding in shear, or are you using it for compression only?

Don't overdo on the torque, especailly on stainless. Run locktite if needed, and consider a fiberlock nut.
 
Posts: 5204 | Registered: September 13, 2006Reply With QuoteReport This Post
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I checked some torque values charts and for stainless A2 or A4 5mm bolt 45.1 inch lbs dry and 40 inch lbs wet. So you are correct.
 
Posts: 804 | Location: New Mexico | Registered: March 21, 2017Reply With QuoteReport This Post
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quote:
Originally posted by jigray3:
I’m replacing 18-8 stainless hardware securing deck hardware to my sailboat. It will experience some sail handling loads so I need to apply maximum torque, but avoid galling. The bolt is 5 mm coarse thread (I think), but the matching nut seems so small and narrow, I’m questioning the torque value I’m finding. Does 45.1 in/lbs sound right?

I work on sailboats for a living and have never used a torque wrench. What size boat and what type of hardware?
 
Posts: 232 | Location: Canyon Lake, TX | Registered: December 22, 2008Reply With QuoteReport This Post
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The issue of torquing fasteners on sailboats is a bit complicated. First because torque numbers are intended for substrates that are solid, like metal parts and bolt stretch is the goal. It is very likely that a sailboat is going through a fiberglass deck (you don't say) that might even be cored (again not much detail) but for sure is where crushing is not only possible but likely. Second deck fasteners absolutely need some form of sealant. And there isn't any book that tells you the torque when its covered in 5200. Lastly if there are small nuts they need big washers to spread the load. You need snug but not crushing or the substrate (a judgement call) and not a torque wrench. The loads will be a fraction of the tensile loads so this is not a critical area on a sailboat any of us is likely to own and use a 5mm fastener.


“So in war, the way is to avoid what is strong, and strike at what is weak.”
 
Posts: 8979 | Registered: October 14, 2004Reply With QuoteReport This Post
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quote:
Originally posted by F_L:
quote:
Originally posted by jigray3:
I’m replacing 18-8 stainless hardware securing deck hardware to my sailboat. It will experience some sail handling loads so I need to apply maximum torque, but avoid galling. The bolt is 5 mm coarse thread (I think), but the matching nut seems so small and narrow, I’m questioning the torque value I’m finding. Does 45.1 in/lbs sound right?

I work on sailboats for a living and have never used a torque wrench. What size boat and what type of hardware?


I too work on boats/yachts for a living and have never used a torque wrench for anything except engine bolts like cylinder head bolts.
 
Posts: 20266 | Registered: June 12, 2005Reply With QuoteReport This Post
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quote:
Originally posted by jimmy123x:
quote:
Originally posted by F_L:
quote:
Originally posted by jigray3:
I’m replacing 18-8 stainless hardware securing deck hardware to my sailboat. It will experience some sail handling loads so I need to apply maximum torque, but avoid galling. The bolt is 5 mm coarse thread (I think), but the matching nut seems so small and narrow, I’m questioning the torque value I’m finding. Does 45.1 in/lbs sound right?

I work on sailboats for a living and have never used a torque wrench. What size boat and what type of hardware?


I too work on boats/yachts for a living and have never used a torque wrench for anything except engine bolts like cylinder head bolts.


Same here, have owned sailboats for 40 years and never used a torque wrench. Ditto the earlier post re: crush possibilities.




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Posts: 3229 | Location: Wichita, Kansas | Registered: March 27, 2011Reply With QuoteReport This Post
Nullus Anxietas
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We had a Pearson P30 and I re-bedded most the stanchion hardware. I never bothered with a torque wrench. I just made 'em good and tight.
But I did a lot of wrenching on cars in a past life, so I've a pretty decent seat-of-the-pants feel for torque.

Btw: For through-deck stuff that'll be under load on a sailboat, backing plates are a beautiful thing Smile




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Posts: 18755 | Location: S.E. Michigan | Registered: January 06, 2008Reply With QuoteReport This Post
Too clever by half
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Boat is 32', and the fitting is a pivoting headsail furling lead block comprised of a sheave that turns the 3/8" furling line about 120 degrees to an integrated cam cleat, so loads on the mounting bolt/nut are compression to bed the block mount with butyl tape, and shear from the ninety degree sail furling loads. Rated working load for the fitting is 300 lbs, though when I removed the original bolts (10/32), one was bent from the loads. I am upgrading the mounting hardware as much as the block mount will allow to the 5 mm 18-8 stainless bolt and nut. I'm told this furling setup is a bit unorthodox, but is how the boat was rigged when I bought it new 27 years ago. Both cleat and sheave were failing, and the block is no longer made, so I cut it apart and rebuilt it with new components.

The block is actually mounted through the aluminum toe rail flange which sits on top of and is rivited to the deck, so the bolts go through both the flange and deck near the hull to deck joint. I don't believe the deck is cored in this area, and I'm using the existing holes. The previous installation used standard washers on the back side, so I have upgraded to significantly larger fender washers and doubled up on them as backing plates.

I have never really felt like I needed a torque wrench on my boat before either, but given the damage to the previous mounting hardware and the fact this spot can cause some real damage if it leaks, I want to make sure to get it good and tight without creating a cold weld. The 5mm bolt looks up to the task, but the standard nut just strikes me as small and thin for the application, and I question how much torque the threads in the nut can stand up to. Not planning to use antisieze because it lowers the torque value and I need it to stay put, and I can't use loctite because of the bedding process recommended with the butyl tape. My plan is to back the standard nut up with a nylock to lock it in place once I have torqued it down 3 times over a span of several weeks. That allows the butyl to ooze into the voids nicely, and done properly the bedding should last another 25 or 30 years and stay dry.

ETA:: - I just returned from working on the fitting after torquing at 30 in/lbs, on my first pass I'd guess I had it in the 20-25 in/lb range. I'll let the butyl adjust for a week or so, then come back with my final torque setting. Probably not going to 41 in/lbs, though. Have to say, I like using the torque wrench here and knowing what it is and that both are the same. Certainly easy enough to do.

Also, I might use loctite and a second standard nut screwed against the first in lieu of the nylock. Thanks for your help, guys.

This message has been edited. Last edited by: jigray3,




"We have a system that increasingly taxes work, and increasingly subsidizes non-work" - Milton Friedman
 
Posts: 10227 | Location: Richmond, VA | Registered: December 11, 2007Reply With QuoteReport This Post
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I was a yacht mechanic for 20 years, never used a torque wrench except on the engine. If concerned about galling, use some grease.


-c1steve
 
Posts: 3131 | Location: West coast | Registered: March 31, 2012Reply With QuoteReport This Post
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Regarding Stainless Steel fasteners and lube.
Just like the Karate Kid.
Wax on.
Wax off.

Anything else will gall.

Want to rip all the threads out of a turbo hot side taking out SS studs?
Heat the area with a torch and spray regular lube.
Works every single time. Except for when the stud snaps off.

Remove same stud by applying heat to the housing with a small torch and wick some wax in.
Stud spins right out with no galling.

Wipe a bit of wax on the threads before assy.

Types of lube affect torque specs also.
Detroit Diesel peanut butter is to be used on high torque fasteners like the head bolts and main cap bolts. Regular engine oil will give a lower torque load.
Use that stuff on smaller bolts and you will break the bolt before it clicks.
I'm glad the rest of the planet just uses engine oil and we don't mess with Detroit's anymore.
 
Posts: 556 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
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quote:
Originally posted by powermad:
Regarding Stainless Steel fasteners and lube.
Just like the Karate Kid.
Wax on.
Wax off.

Anything else will gall.

Want to rip all the threads out of a turbo hot side taking out SS studs?
Heat the area with a torch and spray regular lube.
Works every single time. Except for when the stud snaps off.

Remove same stud by applying heat to the housing with a small torch and wick some wax in.
Stud spins right out with no galling.

Wipe a bit of wax on the threads before assy.

Types of lube affect torque specs also.
Detroit Diesel peanut butter is to be used on high torque fasteners like the head bolts and main cap bolts. Regular engine oil will give a lower torque load.
Use that stuff on smaller bolts and you will break the bolt before it clicks.
I'm glad the rest of the planet just uses engine oil and we don't mess with Detroit's anymore.


I haven't heard the term "Detroit Diesel peanut butter in years ! I've been through more 71 ,53 and 92 Series engines than I can remember. Thanks ! I learned the wax trick over 45 years ago too.
 
Posts: 96 | Registered: January 07, 2020Reply With QuoteReport This Post
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quote:
Originally posted by john crusher:
quote:
Originally posted by powermad:
Regarding Stainless Steel fasteners and lube.
Just like the Karate Kid.
Wax on.
Wax off.

Anything else will gall.

Want to rip all the threads out of a turbo hot side taking out SS studs?
Heat the area with a torch and spray regular lube.
Works every single time. Except for when the stud snaps off.

Remove same stud by applying heat to the housing with a small torch and wick some wax in.
Stud spins right out with no galling.

Wipe a bit of wax on the threads before assy.

Types of lube affect torque specs also.
Detroit Diesel peanut butter is to be used on high torque fasteners like the head bolts and main cap bolts. Regular engine oil will give a lower torque load.
Use that stuff on smaller bolts and you will break the bolt before it clicks.
I'm glad the rest of the planet just uses engine oil and we don't mess with Detroit's anymore.


I haven't heard the term "Detroit Diesel peanut butter in years ! I've been through more 71 ,53 and 92 Series engines than I can remember. Thanks ! I learned the wax trick over 45 years ago too.


I've run 1000's of 71's and 92's and a few 53's over the years in yachts. I can't tell you the last time I ran one. Gotta love the old detroits (pre-DDEC's) as long as they had fuel and you got them running, they'd run with a hole in the side of the block.......the ddec's did start/run nice too though, much much less start up smoke.
 
Posts: 20266 | Registered: June 12, 2005Reply With QuoteReport This Post
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I didn’t read all the replies so apologies if it’s been asked but what material are you bolting to/together?

Metal, wood and especially fiberglass will have a much different answer.

What material are both flanges?





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Posts: 3491 | Location: Seoul | Registered: August 10, 2009Reply With QuoteReport This Post
Too clever by half
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^^^ Stainless mounting bracket bedded to aluminum with butyl tape, then 2 layers of fiberglass, and finally stainless backing plates.




"We have a system that increasingly taxes work, and increasingly subsidizes non-work" - Milton Friedman
 
Posts: 10227 | Location: Richmond, VA | Registered: December 11, 2007Reply With QuoteReport This Post
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Hmmm, without knowing the particulars on the fiberglass I’d hate to guess. Since the actual flange or mounting bracket isn’t fiberglass, that helps, and I’m assuming the fiberglass is completely flat in this area?

When we used to work with a lot of fiberglass in the bleach plants the torques were routinely just a fraction of their metal counterparts. It cracks so easily.

I wouldn’t be bearing down on it by any means with the fiberglass components in there. Especially if in your particular case there is a void or honeycomb type structure in between the two layers. I’d go very slowly obviously with a good star pattern and once it feels snug, then one quarter turn more at most.





14 years to retirement! Just waiting!
 
Posts: 3491 | Location: Seoul | Registered: August 10, 2009Reply With QuoteReport This Post
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