A mud pump is a machine that transports flushing fluid such as mud or water to the borehole during drilling, and is an important part of drilling equipment. Its main function is to inject the mud into the well with the drill bit during the drilling process, cooling the drill bit, cleaning the drill tool, stabilizing the well wall, driving drilling, and bringing the cuttings back to the ground after drilling. In normal circulation drilling, the mud pump transfers the surface flushing medium-clean water, mud or polymer flushing fluid under a certain pressure, through the high-pressure hose, faucet and the center hole of the drill string to directly send it to the bottom end of the drill bit. The purpose of this process is cooling the drill bit, removing the cutting debris and transporting it to the surface.
The mud pump we use is driven by the power machine to rotate the crankshaft of the pump. The crankshaft drives the piston to reciprocate in the pump cylinder through the crosshead. Under the alternating action of the suction and discharge valves, the purpose of pressure delivery and circulation of the flushing fluid is realized.
The valve box of the drilling mud pump is an important component of the hydraulic end of the mud pump. Because the working condition of the mud pump valve box is high pressure, high sprint, high abrasiveness and other harsh working environments. In this way, during the maintenance and repair of the mud pump, the valve box is a vulnerable part that needs to be replaced frequently.
Causes of valve box leakage
The main cause of valve box leakage is long-term high-pressure use, the fatigue of the valve box material, when penetrating cracks occur, the current conditions cannot be repaired.
Due to the extremely bad working conditions of the drilling pump valve, in each stroke, the valve disc and valve seat of the discharge and suction valve have an impact. The higher the pump speed, the greater the impact and scouring wear. Because of this, the working stroke of the drilling pump is not very high. Even so, the working life of the drilling pump valve is still very short. It is one of the weakest links in the drilling pump. The valve disc and valve seat need to be replaced frequently during work.
1. According to the valve box used and maintained, most of the leakage occurs at the fitting surface of the valve seat and the valve box. Therefore, it is necessary to replace the valve seat regularly. At the same time, check the inner and outer walls of the mud pump valve box, When install and replace the valve disc and valve seat, the valve seat must be cleaned to ensure that the valve box and the contact surface with the valve seat are clean and free of dirt. There should be no anti-rust oil on the valve seat, nor any oil stains. Replace the valve disc correctly. The valve seat and careful inspection of the valve box can reduce the fatigue limit of the valve box, thereby extending the service life of the valve box.
2. When a puncture occurs in the valve box, our current repair method is welding, but the effect is weak. Generally, the surface puncture and obvious cracks can be used after the extension and then welded to the original size. Therefore, a good welding repair process has a certain value for extending the service life of the overhaul valve box. However, penetrating cracks cannot be seen by the naked eye. Now we basically rely on experience in repairing, and it is difficult to solve the problem fundamentally. Many mud pump valve boxes are under repairs that cannot be judged as penetrating. The use of the valve box can be determined from the integrity of the surface of the valve box. For some valve boxes with good appearance, they will leak completely as long as they eat high pressure during specific use. Therefore, there will be many repaired valve boxes that cannot be used once they are in the well. The puncture was serious within a few days, causing rework, which significantly shortened the service cycle of our pump head after overhaul.
If it can be ensured that the tools for detecting the hidden damage of the valve box are complete, the hidden damage of the valve box cannot be hidden during the overhaul, and the service life of the valve box can be prolonged through effective repair methods.
At present, the method that can detect hidden flaws is flaw detection, but general machinery repair companies do not have such conditions: first, they are highly professional and do not have specialized technical personnel; second, flaw detection equipment is expensive, even if the valve box is detected as having hidden flaws. Data such as the direction of the hidden wounds can be targeted to determine whether the valve box has repair value. After all, many hidden wounds are difficult to repair. In addition, a large cost is invested in the purchase of new equipment and the valve box that has reached its service life is directly scrapped. , The cost difference of renewal also needs to be further budgeted.
3. Analysis of the situation we currently use: the puncture problem of the mud pump valve box mainly occurs in the Qingzhou pumps. The valve boxes of Lanshi and Baoshi also have punctures, but they are less than the Qingzhou pumps and easy to repair.
Among them, the material problem has a great impact. The situation of ordinary carbon steel and high-quality alloy structural steel is completely different. The welding rod used for machine repair and the base material of Qingzhou valve box doesn't match. There will be more problems after welding repair. The material of Qingzhou valve box is a bit more rigid, so it is easier to puncture and crack.
In summary, at present, our most fundamental and effective way is to pass the standardized operation and inspection of the good team, combined with the overhaul quality of the mechanics' company, try to ensure that the use of the valve box can reach its use limit, and then to scrapped and replaced the valve box with a new one.