Downhole pressure relief valve for well pump

In a well having a string of tubing within casing, a pump secured to the tubing for pumping fluid through the bore of the tubing, an improved pressure relief valve for the pump, comprising:

• a body having a longitudinal axis and mounted stationarily into the string of tubing above the pump, the body having an lower end and an upper end, the body having an axial stab connector portion;
• a main flow passage extending from the lower end to the upper end of the body for conveying fluid being pumped by the pump through the tubing;
• a valve sub having an axial stab connector portion which mates with the axial stab connector portion of the body;
• a profile on an upper end of the valve sub for engagement with a wireline tool for lowering the valve sub through the string of tubing and into engagement with the body with the stab connector portions;
• a valve seat in the valve sub, having an upstream end and a downstream end;
• a spring-biased valve element carried by the valve sub and urged by the spring against the downstream end of the valve seat to maintain the valve seat closed, the upstream end of the valve seat being in fluid communication with the bore of the tubing for applying pressure to the valve element, tending to cause the valve element to move to an open position;
• and
• a discharge passage in the body in fluid communication with the downstream end of the valve seat and leading to the exterior of the tubing for discharging into the casing fluid flowing through the valve seat in the event of excessive pressure opening the valve seat.

A pressure relief valve for a pump suspended in casing in a well on a string of tubing, comprising:

• a body having a longitudinal axis, a lower end and an upper end, the body having threads on its upper and lower ends for securing the body into the string of tubing;
• a central receptacle extending axially downward from the upper end of the body;
• a main flow passage extending from the lower end to the upper end of the body and offset from the receptacle for conveying fluid being pumped by the pump through a bore of the tubing;
• a valve sub having a mandrel which stabs sealingly and releasably into the receptacle;
• a profile on the valve sub for engagement with a wireline tool to lower and retrieve the valve sub through the tubing;
• a valve seat in the valve sub, having an upstream end and a downstream end;
• a spring-biased valve element carried by the valve sub and urged by the spring against the downstream end of the valve seat to maintain the valve seat closed;
• an upstream passage in the valve sub leading from the upstream end of the valve seat to the exterior of the valve sub for communicating pressure of the bore of the tubing to the valve element to tend to cause it to open the valve seat;
• a bypass passage in the mandrel extending from the downstream end of the valve seat to the exterior of the mandrel for communicating the downstream end of the valve seat with the receptacle of the body;
• and
• a discharge passage in the body leading from the receptacle to the exterior of the tubing for discharging into the casing fluid flowing through the valve seat in the event of excessive pressure opening the valve seat.

A method for relieving excess pressure that may occur at a discharge of a well pump suspended on a string of tubing within casing, comprising:

• mounting a pressure relief valve in the string of tubing downstream from the pump, the pressure relief valve being positioned within the outer diameter of the tubing string and having a movable valve element urged by a spring against a valve seat;
• applying pressure in the string of tubing due to fluid being pumped by the pump to the pressure relief valve;
• and
• if the pressure in the string of tubing exceeds a selected amount, causing the valve element to move away from the valve seat, compressing the spring and venting the pressure in the tubing through the pressure relief valve to the casing.