Product Introduction of Valve Cover Sealing Ring
The valve cover sealing ring is an important static sealing accessory in the valve cavity area of the hydraulic end of the drilling mud pump. It is mainly installed at the mating position between the valve cover and the liquid cylinder or valve box, used to seal the leakage channel between the outer circle of the valve cover and the installation hole of the valve cavity, preventing the drilling fluid from leaking out from the valve cover installation position during the operation of the mud pump.
When the mud pump is in operation, the valve cover remains fixed, and the valve cover sealing ring does not participate in the reciprocating motion of the piston or the valve body. Therefore, its main working form belongs to static sealing. After the sealing ring is installed in the specified sealing groove or sealing cavity, an initial seal is formed through the designed compression amount, and the sealing state of the valve cover area is maintained under the working pressure.
The valve cover sealing rings used in the hydraulic end structures of different mud pumps may vary in inner diameter, outer diameter, cross-sectional profile, material, hardness and installation direction. When purchasing, do not replace merely based on the name of "valve cover sealing ring" or a similar outer diameter. Instead, check the structure of the valve cover, hydraulic end and sealing groove simultaneously.
The main function of the valve cover sealing ring
1. Sealing valve cover installation interface: The valve cover sealing ring fills the specified sealing space between the valve cover and the valve cavity of the liquid cylinder, preventing the working medium from leaking out along the valve cover fit clearance.
2. Establish an initial seal: After the sealing ring is installed, it generates a specified degree of elastic compression, ensuring that the sealing surface maintains effective contact with the valve cover and the sealing cavity.
3. Adapt to changes in working pressure: During the operation of the mud pump, the pressure at the hydraulic end changes periodically. The sealing ring of the valve cover needs to maintain stable sealing contact under the corresponding working conditions to prevent external leakage in the valve cover area.
4. Matching the pressure-bearing structure of the valve cover: The valve cover bears the main structural load, and the valve cover sealing ring is responsible for sealing the mating interface. Together with the external compression or locking parts, they form the valve cavity sealing structure.
The working principle of static sealing
After the valve cover sealing ring is inserted into the sealing groove or the specified sealing position, when the valve cover is installed into the valve cavity of the liquid cylinder, it causes a certain elastic deformation of the sealing ring, thereby forming an initial contact pressure between the two fixed mating surfaces.
In sealing structures with pressure self-tightening function, the pressure of the working medium can further make the sealing lip or effective sealing surface adhere closely to the adjacent surface. The specific mode of pressure application depends on the cross-sectional shape of the sealing ring and the installation structure. Therefore, sealing rings of valve covers with different cross-sections cannot be simply replaced according to the same outer diameter.
The sealing ring is not necessarily better when the compression amount is larger. If the sealing groove is too shallow, the cross-section of the sealing ring is too large, or the assembly clearance is incorrect, it may cause excessive compression, shearing, extrusion or premature failure of the sealing part.
The fit relationship with the valve cover
The valve cover and the valve cover sealing ring are two different parts that work in conjunction. The valve cover is a metal pressure-bearing structural component, responsible for sealing the valve cavity, withstanding internal pressure loads and maintaining the structural position of the valve cavity. The valve cover sealing ring is responsible for the interface sealing between the valve cover and the liquid cylinder.
The outer circle of the valve cover, the sealing groove or the corresponding sealing mating surface must be kept in good condition. If there is erosion, corrosion, scratches, burrs or obvious wear at these positions, the new sealing ring may also fail to form a stable seal.
Therefore, when repeated leakage occurs at the valve cover position, it is not only necessary to replace the sealing ring, but also to simultaneously inspect the sealing surface of the valve cover and the sealing mating surface of the liquid cylinder valve cavity.
Section structure and installation direction
The valve cover sealing ring may adopt O-shaped, special-shaped cross-section, lip or other special cross-section structures. The specific form depends on the model of the mud pump and the design of the hydraulic end.
Sealing rings with symmetrical cross-sections usually do not have obvious forward and reverse direction issues. However, for sealing rings with lips, pressure chambers or other directional structures, the pressure-bearing direction and installation direction must be confirmed in accordance with the original equipment requirements.
Incorrect installation direction may cause the seal to fail to self-tighten under normal pressure, and even lead to lip flipping, extrusion or early leakage. Therefore, for seals whose direction cannot be clearly determined by appearance, confirmation should be made based on the original part number, assembly drawing or the original accessory structure.
Sealing groove matching requirements
When selecting the valve cover sealing ring, in addition to the inner diameter, outer diameter and cross-sectional dimensions of the sealing part itself, the diameter, width, depth of the corresponding sealing groove and the assembly clearance should also be checked.
The size of the sealing groove directly affects the compression state and deformation space of the sealing ring. If the width and depth of the groove do not match the sealing cross-section, it may result in insufficient compression causing leakage, or excessive compression leading to overheating, shearing and deformation of the sealing ring.
For pump types that adopt retaining rings or other anti-extrusion structures at high-pressure positions, the number of retaining rings, their installation positions and matching dimensions should also be confirmed simultaneously. Auxiliary sealing parts in the original design should not be omitted.
Compatibility of sealing materials with media
The material of the valve cover sealing ring should be selected based on the technical requirements of the original equipment, working pressure, temperature and drilling fluid system. Different elastomers vary in terms of oil resistance, water resistance, temperature resistance, chemical medium resistance and compressive deformation resistance.
It is not recommended to judge the material merely by the color of the sealing ring when purchasing. The same appearance color does not prove that the material grade, hardness and medium adaptability are the same. Priority should be given to confirming according to the original part number, material specification or technical drawing.
Common failure forms
Common failures of valve cover sealing rings include aging and hardening, compression deformation, cutting, extrusion, lip damage, tearing, surface wear, and expansion or performance degradation caused by incompatible media.
When there are obvious cuts on the sealing ring locally, it is necessary to check whether there are burrs or sharp edges on the valve cover and the installation inlet of the liquid cylinder. If extrusion damage occurs, it is necessary to further check whether the assembly clearance, sealing specifications and anti-extrusion structure are correct.
If the sealing ring fails repeatedly in a short period of time, it is also necessary to check whether the valve cover is correctly positioned, whether the sealing groove is worn, and whether there are any abnormalities in the relevant pressure-bearing parts of the hydraulic end.
Key points for selection
When purchasing the sealing ring of the drilling mud pump valve cover, it is recommended to focus on confirming the following information:
1. Brand, series and specific model of mud pump;
2. Hydraulic end or hydraulic cylinder model;
3. Valve cover model and original part number;
4. The specific installation position on the suction side or discharge side;
5. Inner and outer diameters of the sealing ring;
6. Cross-sectional dimensions of the sealing ring
7. O-shaped, lip-shaped or other irregular cross-sectional structures;
8. Diameter, width and depth of the sealing groove;
9. Whether there are requirements for installation and pressure-bearing direction;
10. Whether it is equipped with a retaining ring or an anti-extrusion ring;
11. Sealing materials and hardness requirements;
12. Working pressure, temperature and drilling fluid system;
13. Original part number, physical sample or technical drawing.
Installation and Inspection
Before disassembling and assembling the valve cover sealing ring, it is necessary to confirm that the slurry pump has been shut down, and the hydraulic end and related high-pressure pipelines have been reliably depressurized. The valve cover must not be disassembled when there is residual pressure in the valve cavity.
Before installation, the sealing groove of the valve cover, the outer circle of the valve cover and the corresponding sealing holes of the liquid cylinder should be cleaned. Remove mud, rust, residues of old seals and metal particles, and check whether there are burrs and sharp edges at the inlet position that may cut the sealing ring.
For special-shaped or lip seals with directional requirements, the direction should be confirmed in accordance with the original equipment assembly requirements before installation. During the assembly process, the sealing ring must not be distorted, flanged, cut or partially come out of the groove.
After the valve cover is installed, it should be confirmed that it is fully in the specified positioning position, and then the corresponding compression or locking parts should be installed. Incorrect sealing specifications or damaged sealing surfaces should not be compensated for by abnormally increasing the external clamping force.
Procurement Instructions
Juli Petroleum Drilling and Production Equipment Co., Ltd. provides valve cover sealing rings and sealing accessories for the hydraulic end valve groups of drilling mud pumps. The valve cover sealing ring is mainly used for static sealing between the valve cover and the liquid cylinder or valve box, and is used in conjunction with the valve cover and the corresponding compression and locking structure. There may be differences in the inner and outer diameters, cross-sectional profiles, sealing grooves, materials and installation directions of the valve cover sealing rings of different mud pump models. When purchasing, it is recommended to provide the mud pump model, hydraulic end model, valve cover model, sealing dimensions, original part number, physical samples or technical drawings for matching verification.