FTM 169: When should we wax nuts?

Fastener Training Minute 169: When should we wax nuts?

This edition of the Fastener Training Minute with Carmen Vertullo was originally published October 21st, 2021 as “Should I be waxing my nuts??” during episode 169 of Fully Threaded Radio.

Well, hi everyone. This is Carmen Vertullo with your Fastener Training Minute, coming to you from the Fastener Training Institute and the AIM Testing Laboratory in a beautiful, El Cajon, California.

I got an email from one of our Prime clients, recently. If you don’t know what an AIM Prime Client is, you should email me or see me in some event we might be at soon. Eric mentioned that I’m now Rockstar, so, I’ll be touring the country soon, and when I do, you can come and see me and and ask for my autograph, and ask me about what a AIM Prime client is and I’ll tell you.

Anyway, today’s topic is not about rock stars or AIM Testing Laboratory Prime clients. It’s about the email I received from an AIM Prime client regarding waxed nuts, and he wanted to know: Should I be waxing my nuts? Well, that is a very appropriate question.

When is it appropriate for you to be waxing your nuts?. That might sound inappropriate but it is an appropriate question. And when I come back, I’ll tell you men when it is appropriate to be waxing your nuts.

In a nutshell, the Fastener industry requires that we wax nuts whenever they come from ASTM A563 as the governing specification, and they are hot dip galvanized and they are over-tapped. The reason for that is, those nuts are used in structural applications with other hot dip galvanized externally threaded fasteners, and therefore, we would have a very uncontrolled torque-tension relationship if we the plane threads of the over-tapped nut, (it is usually going to be a heavy hex nut), going against the hot dip galvanized surface threads of the bolt.

There is lots of friction in there and we just are not properly able to control the torque-tension relationship. So, a lubricant is required. It doesn’t have to be wax but it usually is, and it is supposed to be dry to the touch. So it can’t be like some oily greasy stuff. In some cases, even though it’s not required, it should be colored. Most distributors who supply these nuts will add coloring to the wax so we know it’s there.

There is a supplement in ASTM A563 which requires went in that we add color to the wax, however, it’s not required unless this supplement is invoked.

Now, this particular question came our way not regarding ASTM A563 at which the common grade is DH nuts, which will use what structural bolts such as ASTM A325 grade structural bolts, but this question had to do with 2H heavy hex nuts, which come from ASTM A194.

ASTM A194 is not a structural bolt standard, it’s a standard that covers fastening nuts in particular for high pressure, high temperature applications. Interestingly enough, ASTM A194 actually prohibits us from coating these nuts with hot dip galvanizing, or anything else, unless the user specifically requests it.

It turns out that in ASTM A563, we are allowed to substitute a DH nut with any other nut that has the same strength, (that is proof load and hardness), and it also turns out that in ASTM A194, our 2H nut is a perfect substitute for the A563 DH nut. And since an ASTM A194 2H nut is actually a very common nut, it is often substituted.

Of course, if we’re going to  hot dip galvanize it and over-tap it, we want it to meet the requirements of an A563 DH nut, and we would then also be required to add the wax.

That’s what the standard says. So in a nutshell, again, all of our hot dip galvanized high-strength nuts, whether they are DH or 2H must be waxed. It doesn’t matter if they’re inch and a half or lower which is where our structural bolts come from. It doesn’t matter if they are coarse thread or eight pitch thread. You’re virtually never going to see a fine thread, hot dip galvanized product. If anyone has seen one please let me know, but it could be 8 pitch, it could be coarse thread, but those nuts which are hot dip galvanized and over-tapped, need to be waxed.

So men women, wax your nuts appropriately. I hope you learned something.

This has been Carmen Vertullo with your Fastener Training Minute. Thanks for listening.

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