ASME VIII, M-11 INSTALLATION OF SAFETY AND SAFETY RELIEF VALVES
Spring loaded safety and safety relief valves normally should be installed in the upright position with the spindle vertical. Where space or piping configuration preclude such an installation, the valve may be installed in other than the vertical position provided that:
(a) the valve design is satisfactory for such position;
(b) the media is such that material will not accumulate at the inlet of the valve; and
(c) drainage of the discharge side of the valve body and discharge piping is adequate.