Made in USAPipe Thread (NPT) tapped holes, but for fullest protection against leakage, should be used in dryseal tapped holes which are taper reamed before tappingThe thread truncation is closely controlled at root and crest to assure metal to metal contact, preventing spiral leakage and forming a positive seal without the use of sealing compoundsDry seal plugs can be used in American Standard Taper DrysealA dry seal plug is one having a tapered (0.750 diametral per 12) thread extending its entire length and designed to have its threads mesh tightly with those of a taper-threaded holeBoth ends of the plug shall be flat and chamfered approximately 4