heating element thread size

Hey guys, I have a little problem. I'm in the process of a kal clone and I bought some maytag 5500w ulwd heating elements. They say on the package they are 1 3/8" NPS.

The problem I am having is finding a way to secure them into my vessel.

To be continued...

Take them back and get the ones for 1" NPT. (National Pipe thread) I'm not a plumber and don't remember the TLA ( Three letter acronym)

I did the same thing.

NPT is national pipe tapered threads. Plumbing fittings use this.

NPS is national pipe straight threads and is what most heater elements use.

I've seen 1/2" NPS nuts and 1" NPS nuts but never 1-3/8" NPS. Im sure they exist... I've just never run across them.

I'm 99% sure the packaging is mixing measurements. 1" NPS thread measures 1-3/8" OD. I've never heard of 1-3/8 NPS.

I think Bobby is right about this and here is what you need to secure it in your vessel.
http://www.bargainfittings.com/index.php?route=product/product&product_id=95
Or you can weld in a 1" npt half coupling like I did.

It is actually 1 3/8 od. Sorry I was rushed. I'm at work and we had a call to go on. I purchased a 1" and 1 1/2" npt half couplings. 1" is too small 1 1/2"is too big. So are the camco elements 1" od?

I used an 1 in half coupler with my camco and works great.

I almost grabbed an 1-3/8" element myself by mistake at the local hardware store. Google them - they DO exist and are out there - apparently several brands use that size.....

Yeah, 1-3/8" exist. Easiest, like others said, is to return them and get 1" elements. As noted, They will be 1" NPSM, (straight threads), not 1" NPT (tapered threads). You can make 1" NPSM fit into 1" NPT couplers but with varying results. Many get them to thread in far enough to seat the gasket, and are good. Mine, it seats way early, long before the gasket engages, but a ton of teflon plumbers tape still allows it to seal.