Flanged Valves toolbar: Relief Top 
Command line: HRELF
Places a 90 degree pressure relief valve with the relief end normal to the X-Y plane.
last point
Starts the component at the last point of the previously-created component.
Length
Defines the length of the pressure side and the relief side of the valve.
Relief
Places the relief end at the start point.
Corner
Places the component at the corner of two pipes.
Up
Places the branch of the valve in the positive Z direction.
Down
Places the branch of the valve in the negative Z direction.