NPTF are manufactured according to the ANSI / ASME B1.20.5 standards.

ANPT are manufactured according to the SAE AS71051B standards.

NPTF threads do not require a sealant to create a leak-proof connection, hence they are also known as Dry Seal threads.

Additional gauging is required for NPTF and ANPT threads, as the truncation of these threads must be kept within defined ranges.

To test the size and taper of component threads along the thread length, L1 & L3 plug gauges and L1 & L2 ring gauges are used in conjunction. Six-step procedure the crest diameter and truncation of the component threads along the crest are checked using crest check plugs and ring gauges.

Type Standard Plug Gauges Ring Gauges
NPTF ANSI/ASME B1.20.5 Thread Plug Gauges L1 & L3(Basic Step or Min/Max SL) Thread Plug Gauges L1 & L2(Basic Step or Min/Max SL)
ANPTF SE AS71051B 6 step Crest Crack Plug 6 step Crest Crack Plug


For over a period of 11 years, engaged in Trading and Manufacturing of quality Thread Gauges in India.

Contact Us


  • We are the leading manufacturer of wide range of advanced and high accuracy thread gauges as per customer requirements. Visit our site for more details.

Get In Touch

M/s. Engineering Supplies
46, Forjett Street, 1st Floor, Pulkit Bldg, Opp. SBI, Gowalia Tank, Grant Road (W), Mumbai – 400036, Maharashtra, India.

(+91) 9819669190

© M/s Engineering Supplies