Different tapers on NPT pipe fittings???

[capriracer351]

I am doing a job that requires sealing some thermocouples from water ingress by using a certain taper of pipe plug. The standard is .750" of taper per foot, the print specifically calls for pipe plugs that utilize .875" of taper per foot.

The particular hole that is being sealed is originally tapped for 1/8" straight pipe. The reason for this is because the ring that holds the thermocouple down into this hole has to thread freely almost to the bottom of the hole. Then this special taper pipe plug is to thread into the hole and seal it to prevent water from getting into the well. I assume that the special taper is to prevent the pipe plug from running right down into the hole and on top of the thermocouple and ripping the wire off the top of it. I verified this with a standard taper pipe plug, it ran right to the bottom, and would certainly not seal anything.

My question is this.... Would this taper be an off the shelf item, or would I have to have them custom made??? The reason that I got this job is because the previous supplier could not keep water from getting into the thermocouple well, and also since they were using standard pipe plugs, were running them right down to the top of the thermocouple and pinching the wire. Eventually the T/C's that didn't fail at assembly would fail in the field. I don't want that to happen to me.

Does anyone know of a supplier of this type of pipe plug, or maybe a company that would be able to make these special pipe plugs??? The specific wording on the print regarding these plugs is this: 1/8 NPT, .875" taper per foot, 304 stainless steel.

'85 Mercury Capri
Mild 351 Cleveland powered
6.78 @98 mph 1/8 mile. 1.45 60 ft.

 

[unclesyd]

You might give these people a call.

http://www.precisionfittings.com/plugsmain.htm

 

[JStephen]

First off, NPT implies a standard taper, so the description is a bit screwy right off the bat.

I do find mention of the following thread designations on a google search, but can't locate anything that says what they actually are. Perhaps your threads match one of these, and just have a misleading nomenclature?
PTF-SAE Short Dryseal SAE Short Taper Pipe Threads
PTF-SPL Short Dryseal Special Short Taper Pipe Threads
PTF-SPL Extra Short Dryseal Special Short Taper Pipe Threads
SPL-PTF Dryseal Special Taper Pipe Threads
NGT National Gas Taper Threads