Reduced Torque with Lubricated Bolts

[bcp]

Lubricated Bolts and Reduced Torque

Lubrication effect on bolt tension and torque.

www.engineeringtoolbox.com

Bruce

 

[BravoXray]

What about anti-seize?

 

[grsthegreat]

Anti seize also changes torque ratings.

 

[jeff9366]

Use fine thread bolts and nuts in lieu of coarse thread bolts and nuts.

 

[Streetcar]

Torque is indirect method to determine tension in bolt. Any lubricant will lower torque for given tension on other hand dirt or damage to thread will increase torque for given tension

 

[chim]

https://www.gomog.com/allmorgan/bolttorque.pdf

 

[dadohead]

You can find most everything on the internet. The chart above should have been left where it was found though.

I'm a retired tractor engineer and one of my first training assignments was running the bolt lab for our construction machine division. A sign was in the lab: "torque is what we do; tension is what we want." We also want consistency. On the assembly line, every bolted joint is set to a specification. That spec is determined in the lab; MANY bolted joints were torqued to "proof".... meaning: it is the torque (and tension) of a bolt at its yield point. The torque set on the line is then backed off by the plus tolerance of the wrenching system. Consistancy is everything. If a new shipment of bolts differ (supplier, plating, etc) bolts start breaking on the line.

Every kind of bolt finish imaginable is tested: raw, phos & oil, electro plate, mechanical plate, etc. Oiled bolts can be the most inconsistent of the bunch! Most consistent by far: dry mechanical plated.

Do NOT oil any bolt (on purpose) that a manufacturer has published a spec for. Fine threads don't offer any tension advantage either (any advantage is eaten up in additional thread friction)... because of that, they excel in high vibrational applications. Hope this helps.

 

[chim]

You can find most everything on the internet. The chart above should have been left where it was found though.

Yup. The chart was probably developed by a guy living in his mom's basement. Perhaps some dude with delusions of adequacy. Or mebbe not:

Allied Systems Company

Allied Systems Company designs and manufactures specialized heavy lift and material handling equipment such as cranes and log loaders to winches and balers.

www.alliedsystems.com

 

[gsganzer]

Do NOT oil any bolt (on purpose) that a manufacturer has published a spec for. Fine threads don't offer any tension advantage either (any advantage is eaten up in additional thread friction)... because of that, they excel in high vibrational applications. Hope this helps.

I agree with that on a manufactured device. But it's very common in many industries like oil/gas, chemical and power generation that bolts/studs get coated with anti-seize compounds to prevent corrosion and facilitate future disassembly. Although I've always preferred the Xylan (Flouropolymer) coated studs for these applications.

In the instances where anti-sieze is used, there are charts that give the appropriate torque reduction. It's also important to note that the contact surface of the nut should also receive the coating.

 

[Paystar]

What I find interesting is all the commercial tire dealers around here, when I'd had tires done on my class 8 trucks they ALL oil the threads when they re-install.

 

[dadohead]

Industries have always developed, maintained, and shared best practices. The chart above though, with no source or specific application, posted on a tractor forum... is frightening. The readers here vary widely in experience and the applications of bolts joints used on tractors range from the most benign to safety crirical.

Oil on wheel bolts... might explain why the last time I tried to remove a wheel installed by the dealer it took a 3/4 drive socket, breaker, and a 6' pipe! They said it was that tight for liability. NOT a best practice.

 

[chim]

Industries have always developed, maintained, and shared best practices. The chart above though, with no source or specific application, posted on a tractor forum... is frightening.

If you're referring to the chart I linked to, it WAS developed by an industry. I gave the source (Allied Systems) in Post #8. If you find this frightening, you may want to avoid using the internet. There are some really scary things there.

 

[dadohead]

If you're referring to the chart I linked to, it WAS developed by an industry. I gave the source (Allied Systems) in Post #8. If you find this frightening, you may want to avoid using the internet. There are some really scary things there.

Allied Systems??? A trucking company? So wheel bolts??? Really?

This is exactly why myself and other tractor industry people I know dont come here anymore...

 

[chim]

Nope, not the trucking company. It's a real manufacturer with real engineers. If you want to be unconfused, click below.

Allied Systems Company

Allied Systems Company designs and manufactures specialized heavy lift and material handling equipment such as cranes and log loaders to winches and balers.

www.alliedsystems.com

 

[Lineman North Florida]

Allied Systems??? A trucking company? So wheel bolts??? Really?

This is exactly why myself and other tractor industry people I know dont come here anymore...

Well you're here, just saying.

 

[Texasmark]

What about anti-seize?

Its a lubricant even though spark plug thread lube is a paste as probably others are. If I need one I go to my little packs of that.

Not rocket science. Just thread a nut on a bolt and with your fingers run the nut up to the head of the bolt. Get out your torque wrench and see how many degrees of wrench movement it takes to get to say 50#.

Uninstall the nut and coat the bolt's threads with lube and repeat the test. "Proof is in the Pudding".

 

[Lineman North Florida]

Putting never seize on truck lug nut studs has saved me several times after going and getting new tires installed and the shop hammered them with an air impact wrench, had to take a torch to one once and it ruined the rim , never had a problem since the never seize.

 

[gsganzer]

Putting never seize on truck lug nut studs has saved me several times after going and getting new tires installed and the shop hammered them with an air impact wrench, had to take a torch to one once and it ruined the rim , never had a problem since the never seize.

On the stainless wrapped nuts (like on the Ford F150), it's important to put never-seize on the nut face where it touches the rim, to help prevent galling between the stainless nut and anodized aluminum.

 

[bcp]

Permatex anti-seize:

"Reassemble parte using normal torque values."

"WARNING: Not for use on wheel lug nut or stud applications."

 

[gsganzer]

Permatex anti-seize:

"Reassemble parte using normal torque values."

"WARNING: Not for use on wheel lug nut or stud applications."

I've never put it on the stud threads. Only the nut surface where it contacts the rim when using the stainless wrapped nuts.