BS EN 4836:2018 Aerospace series. Adaptor, Pipe coupling 24$0D Cone up to 35 000 kPa (5 080 psi) Ring-locked fitting. Reducer. Flareless End. Inch Series. Extra Fine Thread Pitch

Dimensions
Quality assurance
Labelling (process)
Pressure
Locking rings
Surface treatment
Roughness (surface)
Tolerances (measurement)
Designations
Packaging
Pipe fittings
Pipe couplings
Marking
Installation
Locking and locating devices
Aircraft components
Surface texture
Mass

Link: BS EN 4836:2018 Aerospace series. Adaptor, Pipe coupling 24{$permalink}D Cone up to 35 000 kPa (5 080 psi) Ring-locked fitting. Reducer. Flareless End. Inch Series. Extra Fine Thread Pitch
Source: BSI Standards