Adjustable (positional) connectors

Published:  08 September, 2016

This article is based on guidance provided in the British Fluid Power Association’s training course titled ‘Small Bore Tubing Integrity Course – using twin ferrule compression fittings’. This month, we continue our look at associated threads, focusing on adjustable (positional) connectors BS EN ISO 6149, ISO-1179 and ISO-11926/SAE J1926.

Some manufacturers and OEMs specify procedures for the tightening of adaptors and hose connectors. Where such information is provided then this should take precedence over the recommendations that are made below.

Where no procedures are available then the following procedures will help to ensure that adaptors and hose connectors are tightened up correctly.

The following information contains recommendations for the assembly of adjustable (positional) style adaptors in straight thread ‘o’ ring ports.

1) Lubricate ‘o’ ring by coating with light oil and install in the groove adjacent to the face of the metal back-up washer, which is assembled at the extreme end of the groove, as shown below.

2) Install the adaptor into the straight thread port until the metal back-up washer contacts the face of the port, as shown below.

3) Orientate the adaptor by turning out, (counter-clockwise) up to a maximum one turn as shown below.

4) Hold the body of the adaptor with a suitable sized spanner, tighten the locknut, (ensuring that the appropriate torque value is used) and washer against the port face, as shown below.

Note: ISO 1179 ‘o’ ring sealing type connectors use a retaining ring to seal instead of a special machine thread lead in. However, the above assembly procedures still apply.

[subhead] More information

The above information has been edited from course booklet for the British Fluid Power Association’s new training course titled ‘Small Bore Tubing Integrity Course – using twin ferrule compression fittings’. For more information about the new course and how you or your staff can enrol, please contact the Association at: For general enquiries, please contact:, or Tel: 01608 647900.

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