Abstract: A pressure relief valve having an external valve body substantially cylindrical, with a bore therethrough positioned atop the exterior of the pipe, an internal stem portion movable within the bore within the valve body, including a tip for extruding in through a bore in the wall of the pipe, a piston member housed within the internal movable valve body movable from a first position locking fluid flow up through the internal body and a second position allowing fluid to enter the internal body and enter a drain port, a spring member intermediate the upper portion of the valve head and the internal body for biasing the piston member in a normally closed fluid bloding position, means on the valve body for imparting force on the upper portion of the internal member for driving the lower tip portion through the wall of a particular type of fluid flow pipe, and insulation means for housing the external valve and for insulating the valve from direct contact with the fluid flow line.