Deep seat ball valve

Abstract

The invention relates to petroleum engineering and can be used in downhole sucker rod pumps that pump mainly liquids with an increased content of mechanical impurities.Ensuring reliable operation in conditions of increased abrasive wear at high temperatures in chemically aggressive environments is ensured by a deep fit, which increases the grinding area of the ball to the seat. The surface area of the lap affects the reduction of specific loads on the valve pair, which provides a reliable seal, as well as an increase in the valve's working life by reducing contact stresses. According to this indicator, the valves made of tungsten carbide have the best values among the investigated valves, which have the highest surface hardness (88-90 NCC) in comparison with other materials.The valve pair with a deep fit ensures the stability of the shut-off element in the seat, which accordingly improves its tightness, increases the working life of the valve pair and wear resistance.

Description

The invention relates to petroleum engineering and can be used in borehole sucker rod pumps that pump primarily liquids with a high content of mechanical impurities. In accordance with GOST R 51896 and API ZRES 11 AX standards, sucker-rod pumps are equipped with valve assemblies depending on the characteristics of the pumped fluid. Valve assemblies are made of various materials: 33 - stainless steel, 3T - stellite (cobalt alloy), TS1 - tungsten carbide. The balls in the valve assemblies of the above-mentioned materials have different specific gravities. The valve assemblies are the most critical component of the pump, as they are subject to the greatest chemical and mechanical stress. Pump valves ensure operation under the harshest operating conditions, including corrosion from salts and water, the destructive action of hydrogen sulfide, and abrasive inclusions. A check valve is known [RU Patent No. 2187709, published 2002.08.20 IPC F04D 15 / 02,] for a borehole electric centrifugal pump, comprising a module-head with a seat and a shut-off element made in the form of a plug made of plastic material with splined grooves, wherein the outer diameter of the splined grooves of the upper end of the plug is greater than the inner diameter of the tubing pipe screwed into the module-head, and the inner diameter of the grooves is less than the inner diameter of this pipe, and the inner diameter of the splined grooves of the lower end of the plug is greater than the diameter of the hole in the seat of the module-head, and the lower end of the plug is made in the form of a cone, a truncated cone, a ball or an ellipsoid, wherein the height of the plug is less than the distance from the hole in the seat to the pipe of the tubing string. The shut-off unit of the check valve [RU Patent No. 2324097, published: 10.05.2008 Bulletin No. 13, IPIK F16D 15 / 00, F16D 15 / 04] is a seat and a shut-off element of various shapes: ball, cone or plate. The seat and shut-off element contact each other in the locked state along the seating surface. Part of the seat, in the area of ​​the seating surface, is made in the form of a cylindrical insert made of titanium nickelide with a critical martensitic strain stress value ac, lying in the range of 350-250 MPa. The part of the seat, which is a conical sleeve, is made of this alloy. The flat washer is made of the same alloy. The valve seal is formed by an annular groove machined into the seat surface and a wire inserted into the annular groove. The wire diameter should be slightly larger than the groove cross-section so that the wire protrudes above the seating surface. The wire is made of an alloy with the same acrylate value.The required acro value is ensured by the alloy's component composition. The critical martensitic stress in the specified range of 350-250 MPa is achieved by the TN-20 alloy. A common drawback of commercially available ball bearings, including those described above, is the instability of the ball's seat fit due to the high center of gravity relative to the seat's lapping surface and the small diameter of the contact surface. As a result, the ball "bounces" several times when seating, subjecting the bearing surfaces to impact loads. On dynamometer charts, this instability manifests itself as damped pulsations along the operating line. Under conditions of increased content of mechanical impurities in the liquid, impact loads lead to increased wear of the lapping surface and loss of tightness. The technical challenge addressed by a valve pair with a deep seat made of hard alloy is to ensure the stability of the shut-off element's seating, increasing its reliability and durability under conditions of increased content of mechanical impurities in the liquid. The technical result is achieved by deepening the seat of the ball in the seat, which leads to an increase in the diameter and, accordingly, the area of ​​the contact annular surface of the "ball-seat" pair while maintaining a constant contact width (at least 0.6 mm) by increasing the radius of curvature (R) and the input edge of the valve seat, increasing the stability of the seat of the ball due to the displacement of its center of gravity relative to the seat, accordingly, increasing the tightness and service life of the valve pair. Increasing the lapping area with an increase in the diameter of the contact surface of the ball-seat pair allows for a reduction in specific loads and contact stresses and an increase in the service life of the valve. The use of deep-seat valve pairs ensures the fundamental tightness of the pair and long-term operation of the valve due to the mutual geometric shape of the mating of the ball to the lapped surface of the seat. A deep-seat ball valve in the closed state (figure) consists of: a seat 1 with a seating surface 2 (with a concave arc profile) and a rounding - R of the upper edge 3, a shut-off element 4 in the form of a ball with a ground contact surface of at least 0.6 mm in width to the seating surface of the seat. Operation of a deep-seat ball valve: seat 1 with seating surface 2 with a rounding - R of the upper edge 3 and shut-off element 4 contact each other in the closed state along seating surfaces 0.6 mm wide. The lapped surface of the seat and operating element ensures a high-quality seal, while the deep seat ensures the stability of the shutoff element, thereby promoting the tightness of the valve pair. Current domestic technology and engineering make it possible to manufacture deep seat ball valves. JSC Munaymash manufactures these valve pairs, which are successfully used at domestic oil production facilities and confirm the intended technical result.

Claims

A deep-seat ball valve comprising a shut-off element and a seat with seating surfaces, a portion of the seat and shut-off element in the area of ​​the seating surface forming a seal, characterized in that the seat has a ground seating surface allowing the center of gravity of the shut-off element to shift toward the lower edge, to a position of static stable equilibrium with a width of the contact surface of at least 0.6 mm, with a radius of curvature of the upper edge depending on the seating depth.