Relief Valve Orientation

One often overlooked aspect of relief valve installation is valve orientation. Many refrigeration professionals are not familiar with the 2017 ASME B&PV Code Section VIII Appendix M-11 recommendation that “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”

Since Appendix M is non-mandatory, facilities are not obligated to adhere to upright relief valve installation. Nevertheless, it is prudent to follow all ASME best practices. When a relief valve with horizontal configuration is identified, we suggest that one of the following actions be taken:

• Modify the Orientation – If space is available, the best option is to modify the valve configuration to the upright position. Since relief valve orientation is typically a low priority item, this can often wait until the next scheduled relief valve replacement.
• Contact the Valve Manufacturer – If the system configuration prevents upright orientation, it is recommended that the manufacturer be contacted to ensure that that valve will operate as designed when installed horizontally. Some manufacturers address this directly in their product literature. For example, in Bulletin K109h Hansen Technologies states that “Pressure-relief valves should be installed upright, although horizontal installation is possible”.