Bolt inspection, vibratory conditions

[SteelMover]

I have a pretensioned bolted connection that always sees a rather high level of vibration where I want to use loctite thread locker to prevent bolt rotation, not safety wire. Does anyone have a clever & durable way of marking the bolts for inspection to determine whether or not there has been any unwanted rotation?

In the past I have ground a thin match line into the bolt head and steel using an abrasive wheel or provided match marks with paint.

Are there any less expensive options other than safety wire that you know of that ENSURE the bolts are not rotating?

Thanks!

 

[Metalfixer]

If they are hex head bolts, for rough service in the Navy we tack welded locking plates. If you have the room for the plates and the material is weldable, it does solve the problem of the bolts rotating. I know this is not the least expensive way, but compared to a failure, it's a bargain.
Larry

 

[CoryPad]

Paint lines are most common. There are coatings available that you spray on the fastener that will crack if the fastener rotates - I don't remember the name, but you can search this site and Google for more info.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mikek10]

Something we have tried in the past is

http://www.jetpress.com/tabid/66/ct...cleId/14/Nord-Lock--WedgeLocking-Washers.aspx

For visual inspection rather than prevention, there are triangular washers you can use - set them to point up - if the bolt comes loose the washer moves. They are often used on wheel nuts of lorries.

This allows for resetting following retensioning which can be a problem with paint marking

 

[Gymmeh]

Like Cory said,
Then use a drip of "Lock Tight"

Then Mark with Steel marker that will leave a (semi)permanent line from the bolt, cross the washer, to the base material. seem mcmaster carr "Metallic Color Paint Markers"

any rotation is easly noticable

 

[Gymmeh]

ps- mike those nord-locks look nice

I dont like Ny-locks, I have seen workers destroy the plastic $h!T with an air wrench.

 

[MintJulep]

Prevailing torque fasteners should be your first choice.

Loctite is fine if you are confident that the threads will be clean.

Safety wire DOES NOT ensure that bolts will not rotate.

Google for Torque Seal for a frangible visual indicator of rotation (it does nothing to prevent rotation).

 

[Gymmeh]

I found this web page with alot more information

http://www.boltscience.com/pages/quality.htm

 

[byrdj]

How about a spray can of contrasting color paint?

 

[IceStationZebra]

A crude method that I have used in the past is a chisel mark similar to the paint lines. The advantage is that the mark can't wear/burn off. ISZ