The threads used on the Jiffy-Tite Plugs offered by DME are NPT (National Pipe Thread). The requirements for NPT are defined in ANSI B1.20.1.
The threads used on the DME Brass Pressure Plugs (inch type) are NPTF (National Pipe Thread Fuel). The requirements for NPTF are defined in ANSI B1.20.3.
It is important to differentiate between the two thread types because they are not the same. In layman terms, the NPTF spec is used with much tighter tolerances, so using an NPTF pressure plug with an NPT thread can reduce the amount of seal. Some customers make up for this using pipe tape and when using pipe tape for any application it is important to use pipe tape that is rated for the intended mold temperatures or environment. However, it is always recommended to use a female thread in the mold plate that is appropriately matched to the intended male thread. If you have further questions regarding the above ANSI specifications, we recommend that you purchase a copy of the specification at an authorized online distributor of ANSI standards. Please note that between the time of posting this information and you obtaining a licensed copy of the standard, the standard may be updated. DME makes no assurance that the standards listed above are current and it is recommended that you check with your authorized distributor of ANSI standards for the latest version of the standards listed above.