I'm looking for a guess on the amount of foot pounds this is. I have no idea, and I'm sure it can be calculated.


We need to torque a 3 inch nut on a machine at work. Specs are not provided in the manual for the machine. We called the manufacturer and were told that they don't know the number. We have been instructed to use our cnc mill to make a box wrench that fits the nut out of 1.5 inch steel and make sure the handle of the wrench can fit in a large piece of pipe. The pipe is supposed to be 20 feet long, and were told to push it with a fork lift till it stops moving. Our fork lifts are toyota 3,000 pound lifts. I can't even imagine the number of foot pounds that has to be.

A lot. I see the pipe being the weak link. Good luck

Try this link if you know the grade of the bolt.

https://www.portlandbolt.com/technical/bolt-torque-chart/

it's not really a bolt

Contact Fraser Shipyard / Northern Engineering in Superior. They will have the proper tooling and experience to torque that.

Its a sencorp thermoformer similar to this. The nut is at the top on that orange plate.

On things like that, you tighten as tight as you can by any means possible. Then go another one quarter turn.

did they indicate the grade of the bolt and nut ?

while a grade 8 bolt 1 inch is about 700 foot pounds

a grade 2 bolt 1 inch is only about 200 foot pounds

I would maybe look into a 4-1 multiplier. Seems a lot safer the their instructions

I wonder if the engineer who designed it knows ?

A 20ft cheater pipe and fork lift = disaster and injury up to and including death

When rebuilt a rock crusher we used a tool called a slap wrench. Use a sledge hammer to drive it around. This is what they look like. Slap wrench Drive it until it doesn't move. From your description though I have my reservations. If it is subject to heat the bolt may break from elongation. I would be on the phone with whoever made the machine as it had to have specs to be built one would think. I would make the wrench 6 point instead of 12 like they show.

I'd love to talk with the moron who gave you those instructions..

Millwright territory.

Whatcha makin?

One of my brothers is a machinist/ fabricator.

He always tells me, tighten 'em to a quarter turn before something breaks.

The good old German torque "guttentight"

On DC-3 of WW II fame the Jesus nut was tightened the same way. If I remember right it was four people on a 20 foot pipe......jk

How much torque is required to tighten a 3” nut?
The formula is rudimentary (K x F x D) = T, the inputs can vary wildly depending on grade finish, etc. Think of a bolt as a spring, the bolt has elasticity and is actually being stretched when tightened, when you loosen a properly torqued nut, the bolt returns to its normal length and shape without deformation.
The danger comes in when you surpass the yield strength of the bolt, the engineering term is Plastic Deformation, after reaching the yield strength, a bolt has become so permanently deformed that it is generally accepted to no longer be safely reusable due to a loss of ductility (when a solid material deforms under tensile stress without breaking).
I would ask a PE to calculate proof load of this application, there would be no way of determining anything scientific with a fork truck and 20’ pipe, ensuing results could be catastrophic.

Solving for (T)
Nut Factor = (K)
Tension = (F)
Bolt Diameter = (D)
T= (K) (F) (D)

Whoever you talked to needs to be fired

What a moron

Squirt of LocTite and 3 ugga-uggas on the impact!