Anti Sieze on studs, VERY DANGEROUS TO DO

K

Kody

New Member
I worked in the USA for almost seven years. Part of my time here was spent as an engineering instructor with BP Oil at one of the main refineries. One morning I noticed that the tradies were liberally applying Anti Sieze to the threads of the ammonia compresser head bolts. These were about 38mm in dia. and about 3m long. The last thing you ever need with this machine is to have the bolts snap when it's running. I very carefully quized the engineer and tradies involved and then sent an e-mail to two of the major bolt manufactures in the US. I asked them about using AntiSieze on the threads of such highly stressed bolts. I already knew what their answer would be, (us Aussies are not dumb!). I had heard some time earlier back home (in Aus) that blokes were snapping their wheel lugs off when simply driving along the road in their 4x4. The problem was in the use of Anti sieze on the studs and nuts for the wheels. The following is the reply from one of the bolt manufactures. The second reply has been lost in transit back home and computer breakdown.


The reply -----
Date: 11/9/99 10:22:53 PM Eastern Standard TimeFrom: Wedgetail1
RE: Anti-seize on boltsDate: 11/4/99 10:14:29 AM Eastern Standard Time
From:
To: Wedgetail
Joe,
When you have a bolted joint you put a specified load on the bolt,
say 96000 pounds load. Then you take same bolt and apply a lubricant to
it, on the threads and the nut face (very important) and apply the same load
the torque can be as little as 1/5 the dry torque value. If you like I can
send you a sheet comparing the two conditions. One dry and one with our 503
lubricant which has a coef of .067 (very slick). If you load the bolt to
35-50% of yield and then use a lubricant yes you can and will over stress
the bolt and probably reach a failure. We at Sweeney have developed a
program that calculates what the torque will be using different lubricants.
If you want to call me and discuss this further please do. 1-888-792-5962
ext 6024. If you would like hard copies of a sample that's ok to, please
send me your fax number.
Your sample below would be as follows:
A .75-10 UNC stud and nut lubricated with oil on the threads and the nut
face torqued to 100 lbs. ft would apply a load of 8,180.881 pounds to the
joint.
A .75-10 UNC stud and nut that has been cleaned and has no lubricant at all,
with 8,180.881 lbs. load applied would take 248.6 lbs. ft.
A .75-16 UNF stud and nut lubricated with oil on the threads and the nut
face with the load of 8,180.881 pounds applied would take only 97.4 lbs. ft
of torque. (Not much real difference)
Now to show the effects of a good quality lubricant:
The same .75-10 UNC nut lubricated with Sweeney 503 lubricant to the threads
only would produce 8,180.881 lbs. load at 77.6 lbs. ft.
A .75-10 UNC nut lubricated with Sweeney 503 lubricant to the head of the
nut only would produce the 8,180.881 lbs. load at 73.05 lbs. ft
Now lets put the lubricant on both threads and nut face.
A .75-10 nut lubricated with Sweeney 503 lubricant to the head of the nut
and to the threads also would produce the 8,180.881 lbs. load at 50.7 lbs.
ft.

As you can see lubricant make all the difference in the world.
248.6/50.7=4.9 time the torque
Sincerely
Bill
Applications Specialist
From:
Sent: Thursday, November 04, 1999 6:39 AM
To:
Subject: FW: Anti-sieze on bolts

The reason the studs were snapping on the 4x4's was that the studs were over-tightened by at least a factor of 5 from simply using Anti-Sieze on the threads and nuts and this put the studs at their maximum load just below the yield point. When the wheel hit a bump in the road, the shock load took the stud (or studs) above their ultimate strength and they snapped. The shear strength of a bolt is half that of the same bolt in tension.
If you tighten your nuts up with an air powered gun or torque wrench after applying Anti-Sieze, you can and will, stress the studs beyond their yield point. The result is broken studs, lost wheel/s and possible injury to all concerned.
Hope this helps you to understand the danger of using Anti-Sieze. :eek:

Kody
 
Grumpy

Grumpy

Moderator
Some interesting reading in that reply, who would have thought a little never seize would do that.
 
Outrage

Outrage

4x4 Earth Contributer
Jarh73 said:
Use a torque wrench with dab of grease and problem solved.

Cheers

Justin
Click to expand...

Doing that is exactly what the problem is that was explained.

Using a lubricant makes it easier to tighten the bolt. How stressed the bolt is, is based on how many turns you can put on it, the more turns the more it stretches, the more stressed it is. (other factors of course but that is the primary cause)

So dry (just throwing in numbers), 1000 Nm of torque, you stress the bolt to 60% of its strength limit.

Use lubricant, it now only takes 500 Nm to have the bolt stressed to 60%, instead you tighten it to the 1000 Nm specified (which results in turning it further than it was meant to), and you overstress the bolt. Hit a bump and it breaks.

Grease is typically used where a thread has deteriorated and lubricant is needed to get the bolt stretched and thus stressed/tight enough to do its job.

Further, torque wrenches are considered to have about a 30% inaccuracy, for the reasons of poor threads/grit, etc. On critical equipment where bolt failure is a major problem, new methods where a bolt is stretched via hydraulics (pressure in linearly stretching is accurate) and then the nut is simply turned to it's meeting face, then the pressure released, is being used more and more. Kind of thing is also considered for underground systems where re-digging up equipment is very costly.
 
J

Jarh73

New Member
Outrage said:
Doing that is exactly what the problem is that was explained.

Using a lubricant makes it easier to tighten the bolt. How stressed the bolt is, is based on how many turns you can put on it, the more turns the more it stretches, the more stressed it is. (other factors of course but that is the primary cause)

So dry (just throwing in numbers), 1000 Nm of torque, you stress the bolt to 60% of its strength limit.

Use lubricant, it now only takes 500 Nm to have the bolt stressed to 60%, instead you tighten it to the 1000 Nm specified (which results in turning it further than it was meant to), and you overstress the bolt. Hit a bump and it breaks.

Grease is typically used where a thread has deteriorated and lubricant is needed to get the bolt stretched and thus stressed/tight enough to do its job.

Further, torque wrenches are considered to have about a 30% inaccuracy, for the reasons of poor threads/grit, etc. On critical equipment where bolt failure is a major problem, new methods where a bolt is stretched via hydraulics (pressure in linearly stretching is accurate) and then the nut is simply turned to it's meeting face, then the pressure released, is being used more and more. Kind of thing is also considered for underground systems where re-digging up equipment is very costly.
Click to expand...

Ok we have to be clear here because before you know it people will read this and put nothing on the threads. Having no lubricant is just as bad as having too much or the wrong type.

Insufficient lubricant means the static torque will be higher than the dynamic and the bolt will be tight enough but not actually streched the fastener enough to maintain clamping force.

No bolts with torque specifications are designed to be torqued up dry. All torque settings assume clean threads lightly lubricated that is a fact.

I dab of grease periodically as the threads become dry combined with a torque wrench will ensure correct tightness.

Torque turn methods are applicable on many types of equipment but that is due to the circumstances of the bolt and the generally high torque required beyond that of a readily available torque wrench.

Numerous torque turn methods require a starting torque done with a torque wrench and again this will assume a clean and lightly lubricated thread.

But again it all assumes clean threads and lubrication.

Also correct use of the torque wrench is critical.

The click must occur as the wrench is being turned, the torque must be dynamic not static. If unsure about tightness you need to undo the fastener and do it up again.

Also consider head bolts, I think we can agree they are a critical component where high accuracy is very important? Every workshop manual will explicitly state that threads must be clean and oiled. That includes oil under the head of the bolt. Lubricant is critical.

The examples given are valid and I do not dispute them but it's about correctly tightening bolts and that does requires lubricant and a torque wrench. The examples in terms of wheel nuts mean that people run the risk of over tightening with the incorrect lubricant for the most part NOT using a torque wrench. The lack of a torque wrench means you can easily over tighten manually with your tyre wrench or socket set.

Cheers

Justin
 
Last edited:
03hilux

03hilux

4x4 Earth Contributer
All vehicle manufacturers who sell in Australia strongley advise AGIANST lubricant on wheel studs. Most of them even say in the owners manual.
I have manuals for a 2003 hilux, a 2011 Rav4, and a 1992 corolla, and all say

"CAUTION. Nver use grease or oil on the bolts or nuts. The nuts may fall off, which could cause serious accident. If there is oil or grease on any bolt or nut, clean it off."
 
J

Jarh73

New Member
03hilux said:
All vehicle manufacturers who sell in Australia strongley advise AGIANST lubricant on wheel studs. Most of them even say in the owners manual.
I have manuals for a 2003 hilux, a 2011 Rav4, and a 1992 corolla, and all say

"CAUTION. Nver use grease or oil on the bolts or nuts. The nuts may fall off, which could cause serious accident. If there is oil or grease on any bolt or nut, clean it off."
Click to expand...

Problem is if the thread isn't nice and clean and free of rust.

Its ideal on a perfect thread and would not be a problem BUT if it gets rusty you run the risk of doing damage to the thread when you undo the nut. Dry threads that are not in perfect condition do strange things when tightened and you run the very real risk of not tightening properly as you are trying to screw together two rusty surfaces.

The real issue here is people over tightening and not under standing correct torque. People over tighten thinking tighter is better but if you add grease and a big gorilla you will get over tightened wheel nuts.

Lightly lubricated and a torque wrench you will get correctly tightened wheel nuts.

Cheers

Justin
 
3

35Henry

New Member
Jarh73 said:
Its ideal on a perfect thread and would not be a problem BUT if it gets rusty you run the risk of doing damage to the thread when you undo the nut.
Click to expand...

Rusty threads are a result of lack of maintenance. Adding lubricant to compensate for that is definitely not the answer. The instructions given by car and bolt manufacturers don't take that into account either.

The workshop manual and owner's manual for my car says the wheel studs should be clean and dry. This aricle Why Wheels Fall Off - Caravan and Motorhome Books , written by a former General Motors research engineer, says

"1. Clean the threads thoroughly and ensure the nuts spin freely on the stud for their full threaded length (discard any that do not, and never use a nut or stud that is or has been corroded). The studs and nuts need to be totally clean, dry, and unlubricated".

The real issue here is people over tightening and not under standing correct torque. People over tighten thinking tighter is better but if you add grease and a big gorilla you will get over tightened wheel nuts.
Click to expand...

Agree 100%. Wheel studs are argueably the most critical bolts on a car. I can't think of any other bolts or studs that have the potential to cause as much destruction and loss of life than broken wheel studs yet they would be the most neglected and abused bolts on the majority of cars. Things like rust, incorrectly set rattle guns, giant oversize wheels, changing wheel offsets, lengths of pipe on wheel braces to get the nuts "nice and tight" plus owners who don't fully understand what they are doing when they change the design of a car all contribute to wheel stud failure.

It may be inconvenient but regularly removing wheels, cleaning the studs and nuts, then replacing them at the correct torque must be done. This is even more essential on 4wds operating in water and mud.

I find it a bit easier on my car because I have a set of off road and street tyres so the wheels are constantly being changed. A strip of folded rag worked backwards and forwards around the studs like a shoe shine rag is all it takes to keep them clean and rust free. The same rag wrapped around a screwdriver and twisted inside the nuts keeps them clean.

Occassionally a nut will get scored on its tapered seat by the wheel. It is always the nut, not the wheel that gets damaged. A new nut soon fixes that.
 
Ralfie

Ralfie

New Member
Great Read and I use to use WD40 on wheel studs when changing Tyres each time I went from road tyre to off road.

I was also changing from Steel rims with steel wheel nuts to alloy rims and the appropriate wheel nuts.

Finally gave up with the alloys as the wheel nuts had a stainless steel case over the head of the nut and got stuffed up with rattle guns not using 6 sided sockets so you get the stainless steel cover deforming. (@ $25 per wheel nut replacement cost)

So coming back to the read I have also read that you should not oil/grease wheel studs and seeing I use a torque wrench, you can understand that you can pull off say 100ft/lb much easier with a torque wrench and it doesn't give you the comfort like when you do it to a dry clean wheel stud the torque wrench feels more consise not like you are stretching the stud. So I do not use a lubricant after having read that in print in the servicing manual.

I can relate this to having put head bolts on using a faulty torque wrench as they are covered in oil and had the wrench set to progressively get to 70ft/lbs snapped 50% of the head bolts, long story short the torque wrench was pulling off double the indicated torque. So I now have a calibrated torque wrench.
 
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