Does anyone know how metal to metal tapered plug valves are manufactured to create a proper seal (For use on LP, per ANSI Z21.15).  Do the plug and body need to be lapped into eachother, should the body be ground, or can close tolerance machining centers provide the required finishes.

The best metal-to-metal seal is derived from fabricating the plug and seat such that they interfere (e.g. .00005-.0001 for a .500 inch dia seat), then lap them during valve assembly to remove the interference. The ideal included angle of the plug downstream of the seat plane should generally be 20-30 degrees greater than that upstream of the seat plane (there are exceptions, based on experience).

We manufacture Teflon plug valve body seals for companies like Xomox, Tyco etc. The Teflon will provide the seal due to it's compressive strength.

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