Abstract: A pressure relief valve which has a body including first and second openings for connection in a line and an interior wall defining a flow-through passageway extending from the first opening to the second opening. The body further includes a chamber having an inlet port and an outlet, the inlet port providing fluid communication between the chamber and the passageway. A guide is removably secured to the body and defines a bore extending into the chamber and an open-ended portion extending away from the chamber. A spindle is slidably disposed in the bore between a first position in which the port is open and a second position in which the disc seats in and closes the port. In the second position, the face of the disc exposed to the fluid in the passageway is recessed from the internal wall a distance no greater than one half the diameter of the passageway. A retention nut is threadingly secured to a portion of the spindle extending into the open-ended portion of the guide.