Till today, in threaded connection world it is governed by 2 kinds -- British Standard Pipe Thread (BSP) and National pipe tapered (NPT).
Thread Identification Guide
BSPT/BSPP/NPT Male Thread Carbon Steel Hex Socket End Cap Inner Hexagon Plug Oil Hydraulic Pipe Fitting-BSPP thread,3I4 inch 2pcs : Industrial & Scientific
Explanation of common threads including BSP & NPT
NPT & BSPT Thread - QC Hydraulics
BSPT/BSPP/NPT Male Thread Carbon Steel Hex Socket End Cap Inner Hexagon Plug Oil Hydraulic Pipe Fitting-BSPP thread,3I4 inch 2pcs : Industrial & Scientific
American threaded pipe nipple (TOE) - TPMCSTEEL
Explanation of common threads including BSP & NPT
Excellent Thread Pipe /Galvanized Pipe with NPT Thread and BSP Thread Coupling Acc to ASTM A53/ BS1387 Standard Manufacturers and Suppliers China - Customized Products Factory - HUIKE
Excellent Thread Pipe /Galvanized Pipe with NPT Thread and BSP Thread Coupling Acc to ASTM A53/ BS1387 Standard Manufacturers and Suppliers China - Customized Products Factory - HUIKE
Pipe Fittings Co 45 degree y