I inquire needle valve manufacturers for Class 4500 pressure ratings.(For example Fujikin needle valve)Please verify that you require needle valves rated 4500 psig or other such rating as well as the size such as NPS 1/2 etc. Class normally describes a valve connecting flange class such as ASME B15.5 Class 600 raised face flanges. Few needle valves are flanged and B16.5 stops at class 2500 (PN420).Swagelok sells fittings rated 60 000 psi. Autoclave Engineers sells components rated to 150 000 psi. Needle valves may not be rated as high as the fittings but would cover 4500 psi.Valve built-in to the line with screw structure.Fujikins decleration is ;"The valve is rated at ANSI Class 4500 for pressures.At temperature at 38