Band clamps

[Ian_Edwards]

This may be a bit technical ... but hear goes anyway. I was trying to figure out or find out how to calculate the correct the correct torque for a band clamp (hose clamp/jubilee clip) so that it will withstand the working pressure in the cooling system.
I know it’s a bit extreme; I normally tighten them as much as I can without breaking the worm drive ..... but having just destroyed a couple of clamps by over “gorillaring” them I was wondering how to do it properly.
There must be a formula that links the torque applied to the worm drive, to the tension in the band clamp, to radial compression force, and via a friction coefficient to the working pressure.
I’ve tried searching the web ..... but can’t find anything .... does anyone out there know how to calculate it? Or point me in the right direction? ... Yes, I know there could be several answers to that one!

 

[mikemonty]

I reckon you are overthinking this one.
The torque and therefore tension you can apply is far in excess of anything the system will generate - just don't horse the clamp up so tight!
Use a screwdriver or a 1/4" drive socket drive and tighten until the worm is screwdriver-tight. Anything more is just likely to damage the tubing or whatever you are clamping,

 

[2Tizwoz]

All available here

I cannot honestly say that I would be bothering to use a torque wrench to tighten a hose clip however. As suggested above monitor the hose also whilst tightening and in critical applications use two hose clips.

 

[andy01842]

A large amount of the torque applied to the screw of a “jub clip” is lost in friction. A little lubrication makes a lot of difference. A bit more tightening also loses a lot of the strength of the clip/joint. Very cheap clips are almost useless.

 

[BlueLancer]

use a flexable hex drive for your hose clips vey difficult to over tighten with this tool, also very good for those hard to get to clips that some genius always fits, when the engine is out the boat.
yours aye
steve

 

[Ian_Edwards]

Thanks,
I'm amazed at how low the ultimate torques are, no wonder I've managed to destroy a couple of them.