Tab Washers

[Daparojo252]

I am need of preventing a M42/M45./M48 Nut from coming loose during operation whilst underwater on a pumping application. It will be exposed to seawater and vibration, so has to be resitive to saltwater corrosion. 316,304 and 303 Stainless Steels can be problematic under those conditions due to pitting etc. I am currently leaning towards Monel 400.

A Tab Washer is the preffered method of preventing the Nut from turning. Tab Washers at that size are only available in Steel and still hard to come by, especially in the materials we would require so we may have to look at getting some manufactured to our design. Quantities are not great i.e. less than 1000.

I would be looking at a material that in sheet form the thickness of the washer would be less than 2mm with a 16mm long tab to bend. Would Monel 400 easily bend and keep shape? Or is there a more suitable material or solution?

Many thanks

 

[MJCronin]

There are many types of locking devices for bolting applications.

Each has its own advantages and disadvantages......

I believe that you should consider the Nord Lock washers.

http://www.nord-lock.com/nord-lock/wedge-locking/washers/introduction/

They were developed in Europe, have been in use for decades and are the preferred choice of military and aerospace applications. They have been in use in seawater service andy are available in Inconel, 254 SMO and. the bad boy C-276 ....

Please respect us and complete this thread, let us know of your final decision ...

Best Regards

MJCronin
Sr. Process Engineer

 

[Daparojo252]

I had a look at Nordlok, but the size they do is up to M39

 

[racookpe1978]

tab washers are simple to make - but are expensive to make in odd sizes and materials that are not sold frequently.
So, few are made in the hundreds of thousands needed to make a commercial stamping and fabrication die run profitable.

But. You don't have many to make, and they are going to be made in large sizes of expensive material for a low number of production pieces.

Put out for bid a request for the pieces to be automatically plasma cut by a local shop of the stainless alloy at the diameter and thickness you need. Then insert them, bend up the tab, and tack-weld the tab to the nut, and the other tab to the base metal. When you need to remove the nut, expect to have to cut off the nut, or grind out the tack weld.

Each washer should be 10.00 to 15.00 dollars. Or less.

 

[Tmoose]

Hi MJCronin,

"(Nord-lock washers) are the preferred choice of military and aerospace applications."

Do you know of any MIL specs, etc, that allow Nord Locks ?

thanks,

Dan T

 

[EdStainless]

Or buy some 'as-cold-rolled' M400 sheet and have them water jet cut. 400 is fairly soft and very ductile, even when slightly cold worked.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[SnTMan]

Getting them made should be no big deal these days. A previous employer had them made for Mil spec work to keep for stock.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand