Product Introduction of Valve Cover
The valve cover is an important pressure-bearing accessory in the hydraulic end valve cavity area of the drilling mud pump. It is installed at the maintenance opening position corresponding to the suction valve or discharge valve, mainly used to seal the hydraulic end valve cavity, and together with the valve cover sealing, pressing or locking parts, forms a reliable static sealing structure.
During the operation of the mud pump, the suction valve and the discharge valve need to be periodically opened and closed along with the reciprocating motion of the piston, while the valve cover remains in a fixed position to seal the opening of the valve cavity. At pressure-bearing positions such as the discharge side, the valve cover and its matching structure need to withstand the axial load formed by the internal pressure at the hydraulic end. Therefore, the pressure-bearing end face of the valve cover, the sealing fit part, the positioning dimension and the clamping structure all belong to important technical parameters.
The valve cover is also an important disassembly and assembly part for the maintenance of the valve group. After removing the external locking or pressing parts and taking out the valve cover, the valve, valve seat, spring and guiding parts can be inspected and replaced according to the specific pump structure.
The main function of the valve cover
1. Closed valve chamber: The valve cover is installed at the opening position of the hydraulic end valve chamber, separating the internal working chamber from the external environment. It is an important component of the pressure-bearing boundary of the valve chamber.
2. Provide a mating basis for static sealing: The valve cover works together with the valve cover seal through the outer circle, end face, sealing groove or corresponding mating structure to prevent high-pressure drilling fluid from leaking from the maintenance opening of the valve cavity.
3. Bearing and transmitting pressure loads: The internal pressure at the hydraulic end acts on the effective pressure-bearing area of the valve cover to form an axial load. This load is transmitted to the hydraulic cylinder or valve box through the valve cover and the external compression and locking structure.
4. Form a valve assembly maintenance passage: The valve cover adopts a detachable design, facilitating maintenance personnel to enter the corresponding valve cavity to maintain parts such as the valve, valve seat, spring, and valve stem guide.
The pressure-bearing and sealing principle of the valve cover
The valve cover body is usually a rigid pressure-bearing part. The interface seal is usually achieved by the sealing ring or special sealing parts that are matched with it. After the valve cover is installed into the corresponding hole cavity of the liquid cylinder or valve box, the seal forms a compression at the specified installation position, thereby closing the leakage channel between the valve cover and the valve cavity.
External compression parts, locking parts or threaded structures are responsible for maintaining the correct axial position of the valve cover and preventing abnormal movement of the valve cover under internal pressure. Therefore, the valve cover, seal and external locking structure belong to a system that works in coordination with each other. It is not possible to determine whether they can be interchanged merely based on the outer diameter of the valve cover.
The difference from valve cover sealing
Valve cover: It is a metal pressure-bearing and sealing structural component, responsible for sealing the valve cavity, withstanding pressure loads, and providing an installation mating surface for the sealing parts.
Valve cover seal: It is a static seal installed between the valve cover and the cylinder or valve box, relying on a specified compression and sealing structure to prevent drilling fluid leakage.
If the valve cover seal repeatedly leaks, in addition to replacing the sealing parts, it is also necessary to check whether there is erosion, scratches, corrosion or dimensional abnormalities on the valve cover sealing mating surface, sealing groove and the corresponding hole cavity of the liquid cylinder.
The difference from the valve cover clamping part
Some mud pump valve cavities adopt a combined structure of valve covers and external pressure caps, pressure covers, threaded locking parts, etc. In this structure, the valve cover and the external compression part cannot be mixed as the same component.
The valve cover is located on one side inside the valve cavity, directly forming a sealing fit between the valve cavity closure and sealing. External compression or locking parts maintain the axial position of the valve cover through structures such as threads, reliably confining the valve cover within the opening of the valve cavity.
The valve cover locking methods adopted by different mud pumps vary. The specific structure should be based on the corresponding pump type part drawing and assembly drawing.
The fit relationship with the valve group
The valve cover is located at the external closed position of the valve cavity of the suction valve or discharge valve, and the inner side corresponds to the valve, valve seat, valve spring and related guiding structure. For some pump types, the valve cover or its matching parts may also be involved in the positioning or guiding at the upper end of the spring. The specific determination should be based on the structure of the hydraulic end.
The installation height of the valve cover and its internal structure cannot be changed at will; otherwise, it may affect the assembly relationship of the valve spring, guide vane or other valve group parts. Therefore, when selecting the model, in addition to the external installation dimensions, it is also necessary to verify the inner structure of the valve cover and the fit dimensions with the valve group.
Suction side and discharge side valve covers
According to the design of the hydraulic end of the mud pump, the maintenance opening structure of the suction valve cavity and the discharge valve cavity may be different. Correspondingly, there may also be differences in the diameter, height, sealing structure, inner profile and locking method of the valve cover.
Therefore, it cannot be concluded that the suction side and the discharge side can be interchanged merely because the appearance of the two valve covers is similar. When making a purchase, the specific installation location should be clearly defined, and priority should be given to matching it with the model of the mud pump and the original part number.
Common Failures and Inspections
When inspecting the valve cover, special attention should be paid to checking the outer circle of the sealing fit, the sealing groove, the pressure-bearing end face, the positioning step, the inner working surface, and the force-bearing position in contact with the compression structure.
Common abnormalities include erosion of the sealing surface, damage to the sealing groove, end face indentation, corrosion, local wear, plastic deformation and structural cracks, etc.
If there is mud leakage in the valve cover area, the valve cover seal, the valve cover sealing surface, the liquid cylinder installation hole and the external compression structure should be inspected simultaneously. It is not advisable to deal with leakage simply by increasing the clamping force when the sealing surface is already damaged.
Key points for selection
When purchasing valve covers for drilling mud pumps, 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. Installation position on the suction valve side or the discharge valve side;
4. Outer diameter of the valve cover and total height;
5. Diameter of the valve cover insertion or positioning part;
6. Position the diameter and height of the steps;
7. Dimensions of the pressure-bearing end face and inner contour;
8. Diameter, width and depth of the sealing groove;
9. Sealing specifications for the matching valve cover;
10. Model of the matching pressure cap, pressure cover or locking part;
11. The mating structure with the valve spring or valve stem guide, if any;
12. Disassemble and assemble tools in coordination with the structure, if any;
13. Original part number, physical sample or technical drawing.
Installation and Maintenance
Before disassembling or assembling the valve cover, it is necessary to confirm that the mud pump has been shut down, and the hydraulic end and related high-pressure pipelines have been reliably depressurized. Do not disassemble the valve cover or external locking parts when there is still residual pressure in the valve cavity.
Before installation, the outer circle of the valve cover, the sealing groove, the positioning step and the corresponding installation holes of the liquid cylinder should be cleaned. Check whether there is any sand, rust, burrs or scratches on the sealing mating surface.
After replacing the valve cover seal, it is necessary to confirm that the specification and installation position of the seal are correct to avoid twisting, cutting, squeezing or coming out of the groove during assembly.
The valve cover should be kept in the correct direction and fully positioned, and then the corresponding clamping or locking parts should be installed. The specific fastening method and parameters should be carried out in accordance with the corresponding mud pump maintenance data, and it is not advisable to use a uniform empirical torque.
Procurement Instructions
Juli Petroleum Drilling and Production Equipment Co., Ltd. provides valve covers and hydraulic end valve group accessories for drilling mud pumps. The valve cover is mainly used to seal the suction or discharge valve chamber, and together with the valve cover sealing and compression locking structure, it establishes a reliable pressure-bearing sealing interface. There are differences among various models of mud pumps in terms of the outer diameter of the valve cover, height, positioning steps, sealing grooves, inner structure and locking methods. When purchasing, it is recommended to provide the model of the mud pump, the model of the hydraulic end, the installation position, the matching seal, the original part number, the physical dimensions or the technical drawings for matching verification.