PRODUCTS > AIRLINE & THREADED FITTINGS > ABOUT THREADED (SCREWED) FITTINGS

UNDERSTANDING THREADED FITTINGS

PIPE THREADED (SCREWED FITTINGS) ARE COMMONLY USED FOR MANY APPLICATIONS. WHEN DECIDING ON WHAT FITTING TO USE IT IS IMPORTANT TO UNDERSTAND THE FOLLOWING.

PIPE IS MEASURE BY THE NOMINAL BORE (NB) AND IS THE MOST DIFFICULT TO MEASURS, AS NOMINAL BORE MEANS "NOT ACTUAL" OR "EXISTING IN NAME ONLY". A DIFFICULTY OFTEN ENCOUNTERED IS UNDERSTANDING BSP (BRITISH STANDARD PIPE) AND NPT (NATIONAL PIPE TAPER) PIPE THREAD SIZES. BSP/NPT IS THE THREAD ON THE OUTSIDE OF THE PIPE (FOR MALE THREADS). PIPE WITH A NOMINAL DORE OF 1/4" HAS A WALL THICKNESS AROUND 5/32" WHICH GIVES AN OVERALL DIAMETER CLOSE TO 9/16", FOR THIS REASON SOME CONFUSION ARISES WHEN A MALE THREAD OF ABOUT 9/16" OD IS REFFERED TO AS 1/4" BSP OR NPT.

PRESSURE

BRASS - 500PSI / 3450KPA
STEEL - 3000PSI / 21000KPA
STAINLESS STEEL 316 - 150PSI / 1030KPA
GAL - 200PSI / 1400KPA
PLASTIC POLYAMIDE 6 - GENERALLY 150PSI / 1030KPA

THREADS

BSP
NPT
BSPP (BRITISH STANDARD PARALLEL)