Screw fitting is 1/4" × 40 TPI. GV-A1 1/4-40 Pipe 90 Globe Valve for Live Steam. Bore: 3mm. Globe Valve length: 28mm. 1 × 90 Globe Valve. Accessories for the small wrench.
1/4 x 40 TPI Brass Union Nuts for 3mm Pipe, Live Steam, Pack of 10
1/4"x40 TPI Brass Displacement Oiler for Live Steam Engines - Microcosm
GV-A2 Inline Globe Valve 1/4 x 40 TPI Brass Valve for Live Steam Models
M7D Displacement Lubricator 1/4x40 TPI Brass for Steam Engine
M7C Steam Engine Displacement Oiler 1/4x40 TPI Brass Lubricator