JIS B 8246 specifies the screw threads used in valves for high‑pressure gas cylinders.

The thread form is a 55‑degree rounded‑crest triangular thread, and the pitch is measured along the axial centerline. 

Thread Type: Face Right Angle
* “Face‑right‑angle” means that the thread is perpendicular to the tapered surface.

Taper angle: 3/26 

The thread shall be a right-hand thread.