Product Introduction of Plunger Fixing Bolt Assembly
The plunger fixing bolt assembly is an important fastening component of the plunger transmission connection part of the plunger pump. It is mainly used to reliably fix the plunger on the plunger rod, crosshead or corresponding connection end, and maintain the correct axial connection relationship between the plunger and the reciprocating mechanism at the power end.
When the plunger pump is in operation, the crankshaft, connecting rod and crosshead mechanism convert rotational motion into reciprocating motion and drive the plunger to perform reciprocating motion through the plunger rod or the connecting end. The plunger fixing bolt assembly is located at this connection position and needs to maintain the reliable fixation of the plunger under continuous reciprocating load and vibration conditions to prevent axial loosening of the plunger or abnormal connection status.
Depending on the specific structure of the pump type, the plunger fixing bolt assembly, in addition to the fixing bolt body, may also be equipped with flat gaskets, copper gaskets, sealing gaskets, O-rings, anti-extrusion rings or other holding parts. Therefore, when purchasing, it is necessary to verify against the complete assembly structure of the original equipment. It is not advisable to replace merely based on the diameter and length of ordinary bolts.
Main function
1. Fixed plunger: Lock the plunger onto the plunger rod, crosshead or corresponding connection end through threaded connection to maintain the correct axial installation position of the plunger.
2. Transmitting reciprocating force: During the reciprocating motion of the plunger, the fixed components need to cooperate with the connection end to bear alternating loads, ensuring that the motion at the power end is reliably transmitted to the plunger.
3. Maintain the assembly position of the plunger: Coordinate with the plunger end face, positioning step, gasket and connection structure to restrict abnormal axial movement of the plunger and maintain the correct positional relationship between the plunger and the packing seal system.
4. Matching sealing or anti-loosening parts: For some pump types, the plunger fixing bolts are also equipped with O-rings, anti-extrusion rings, copper gaskets or sealing gaskets. The specific functions and combination forms should be determined according to the original pump structure.
Installation position and transmission relationship
The plunger fixing bolt assembly is usually located at the connection end between the plunger and the plunger rod or crosshead. After the plunger assembly is installed in the corresponding connection position, the fixing bolt is inserted from the end of the plunger and fits with the threaded holes of the crosshead, plunger rod or internal connecting parts, thereby axially locking the plunger.
The other end of the plunger enters the packing box and the working area of the hydraulic end. Therefore, the assembly state of the fixed end will affect the axial position and reciprocating motion state of the plunger. If the fixed position becomes loose, it may further cause abnormal shock, vibration and abnormal working condition of the plunger seal system.
Component structure
The plunger fixing bolt assembly does not necessarily consist of only one bolt. Different plunger pumps may adopt different component combinations based on the plunger material, connection end structure and sealing requirements.
Common structures may include plunger fixing bolts, fixing washers, and corresponding sealing or anti-extrusion parts. For instance, in some maintenance structures of plunger pumps, the fixing bolts are equipped with copper washers, O-rings and anti-extrusion rings simultaneously. Some other ceramic plunger structures use fixed bolts in combination with fixed washers.
Therefore, the specific number of components, gasket form and sealing structure of this product shall be subject to the original part number, assembly drawing or physical object of the corresponding plunger pump.
The difference from ordinary bolts
The plunger fixing bolts are special fasteners in the plunger reciprocating connection mechanism. Their threads, lengths, bolt head structures, washer combinations and installation requirements all need to match the plunger and the connection end.
It not only undertakes the general fastening function, but also directly relates to the axial fixation and reciprocating motion connection of the plunger. Therefore, ordinary bolts with similar shapes cannot be used as substitutes without confirming the specifications, strength grades and original equipment requirements.
Common examination areas
During maintenance, special attention should be paid to inspecting the threads of the fixed bolts, the bolt heads, the transition positions of the rods, and the matching washers. It is necessary to observe whether there is any thread damage, loosening marks, deformation, cracks, abnormal wear or indentation on the contact surface.
For components equipped with O-rings, anti-extrusion rings, copper gaskets or sealing gaskets, after disassembly, these parts should also be inspected in accordance with the corresponding pump type maintenance requirements. Parts that are specified to be replaced after disassembly should not be reused.
If the connection position of the plunger repeatedly becomes loose, the end of the plunger, the connection thread of the crosshead or plunger rod, the positioning end face and related mating parts should also be inspected. It is not advisable to only replace the fixing bolts while ignoring the wear of the connection end itself.
Key points for selection
The plunger fixing bolt assembly is a dedicated component that directly matches the plunger and the transmission connection end. When purchasing, it is recommended to focus on confirming the following information:
1. Brand, series and specific model of plunger pump;
2. Piston diameter and piston structure;
3. The connection method between the plunger and the crosshead or plunger rod;
4. The diameter, pitch and effective length of the fixed bolt thread;
5. Total length of bolts and structure of bolt heads;
6. The outer diameter, inner diameter and thickness of the matching gasket;
7. Whether it is equipped with O-rings, anti-extrusion rings or other sealing parts;
8. The bolt grades and fastening requirements specified for the original equipment;
9. Original part number, physical component or technical drawing.
Installation and Maintenance
Before installation, check the fixing bolts and the internal threads of the connection ends, remove oil stains, foreign objects and residues, and confirm that the plunger positioning end face, gasket and other matching components are installed correctly.
The thread treatment method of the fixing bolts, whether thread locking agent is used, and the final tightening torque should be strictly carried out in accordance with the maintenance requirements of the corresponding plunger pump manufacturer. The bolt sizes, materials and connection structures of different pump types vary, and a uniform empirical torque should not be used for fastening.
For structures such as ceramic plungers that are more sensitive to assembly forces, installation should be carried out in accordance with the prescribed sequence and torque to avoid plunger damage caused by improper force on the fixing bolts.
Before disassembling and assembling the plunger fixing bolt assembly, the shutdown, pressure relief and power isolation should be completed in accordance with the equipment operation procedures. Maintenance can only be carried out after confirming that there is no accidental start-up or residual pressure in the equipment.
Procurement Instructions
Juli Petroleum Drilling and Production Equipment Co., Ltd. provides plunger fixing bolt assemblies and related accessories for plunger pumps. The fixing bolts of different pump types may vary in terms of thread, length, bolt head structure, gasket combination and sealing accessories. When purchasing, it is recommended to provide the pump model, plunger specification, original part number, complete physical assembly or technical drawings to accurately verify the product.