Technical Information

Pressure Ratings

Use our online Working Pressure Calculator

Working pressures quoted are taken from the relevant standard and are provided as a guide only.
Fittings are generally designed with a 2 to 1 proof pressure and 4 to 1 burst pressure.
i.e. working pressure = 1000psi > proof pressure = 2000psi > burst pressure = 4000psi.
Working pressures given in this document, cover the pressure at which a connector is designed to operate at for a number of repetitions to assure adequate service life.

Important – Because many factors influence the pressure at which a system performs satisfactorily, these values shall not be taken as guaranteed. For every application, it is recommended, that all systems should be tested prior to use.
To determine the correct pressure rating for an adaptor, determine the ratings for each connection and take the lowest as the adaptors maximum working pressure.
i.e. 1/2″ BSP Male @ 315 Bar x 1″ BSP Male @ 200 Bar = 200Bar
Adaptors are designed to be used between -40°C and 120°C with no pressure reduction, temperatures exceeding 120°C will result in a drop in working pressure of :-
120°C > 150°C = 11%
150°C > 200°C = 19%
200°C > 250°C = 28%

Torque Values

Tightening torques relate to counterpart made from steel, with lightly oiled threads, and should be used as a guide only.


Burnett and Hillman are certified to ISO 9001, a copy of our latest certificate is available for download here.

Threads and Dimensions

BSP adaptor dimensions are compatible with ISO 8434-6 and BS 5200.
BSP DIN spec adaptors are to DIN 3852 Form A.
BSPP and NCB threads are to BS EN ISO 228-1.
BSPT threads are to BS EN 10226-1.
JIC adaptors are to SAE J514.
JIC and SAE threads are to BS 1580.
JIS are to JIS B 8363
Metric threads are to BS 3643-2.
NPTF threads are to ANSI B1 20.3


Acid zinc plating is to ISO 2081, Fe/Zn8/A/T2.
Fe = Ferrous substrate.
Zn8 = Zinc coating 8 microns thick.
A = Clear passivate.
T2 = Application of organic or inorganic sealants.


Steel used for stock parts are 230M07Pb or 11SMnPb37 as to BS EN 10277-3.
Stainless is grade 316 to BS EN 10277-1.
More details are included in Materials and Regulation section.
Further information is available on request.

DESIGN DETAILS AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT PRIOR NOTICE – Whilst every effort has been made to ensure the accuracy of the information supplied herein, Burnett & Hillman cannot be held responsible for any errors or omissions (E&OE). Working pressures quoted are taken from the relevant standard and are provided as a guide only.