1. Failure analysis of power terminal

(1) the shaft burning and the wear of the copper sleeve in the connecting rod assembly part

The connecting rod is the component connecting the crankshaft and the crosshead in the connecting rod mechanism of the power end crank. The one which is connected to the crankshaft is known as the big head, which is fitted to the semicolon, which contains the 08 high tin alloy thin-wall bearing, which is attached to the cross head, which is called small head, and is fitted with bronze bushing. In the process of the functioning of the power end, due to the fit clearance is too small, or large clearance between pressure build up, liquid film lubrication is not stable, the bearing shell and a lot of heat due to friction between the crankshaft, the temperature increases rapidly between the two, and in the case of not being able to cool in time, the heat accumulates in the shaft. Between the liner and the crosshead pin due to the small clearance, long friction,
And bushing with the crosshead pin with the lubrication between the crankcase oil duct into the crosshead slide, again through the reciprocating movement of the crosshead, lubricating oil tank by cross into the connecting rod small head bushing, lubrication of the crosshead pin. Once the lubrication is due to the dry friction between the liner and crosshead pin, the surface of crosshead pin is hardened by quenching, resulting in the wear of bushing.

(2) wear of crosshead slide

The oil field effluent of the booster pump is highly corrosive, so it is easy to cause the corrosion and wear of the pump in the long run and running process. In particular, the clearance between the crosshead and the sliding way causes the crosshead center to fall due to the greater wear and tear, resulting in the friction between the top rod of the crosshead and the inner hole of the oil seal. This causes the oil to be exposed to large quantities of oil, and the sewage enters the crankcase, combined with high chloride ions and other corrosive ions in the sewage, and produces a large amount of crystallized salt particles. In the end, the cross head and the slide are stuck, and then the crosshead will continue to move, which will cause the scuff and burn.

The analysis of the failure of the liquid end

(1) damage to the intake valve and drain valve

The inlet valve and drain valve are collectively referred to as pump valve, which is usually composed of seat, valve sleeve, valve plate and spring.

It is a device that guarantees the flow of liquid in one way, and the main function is to make the studio connect or separate from the suction or discharge line in a timely manner. Because the sewage is corrosive, and the booster pump is often relocated, the cutting and welding of the import and export pipeline is easy to get the slag into the pump head. In this way, the impact of high pressure water flow and the abrasion of impurities make the sealing reliability of pump valve repeatedly open and close in acid medium gradually decrease, resulting in leakage of valve after closing. The pump valve damage is mainly manifested in the grinding of the seat and valve disc, as well as the fracture of the spring. As long as there is one occurrence, the sealing performance of the pump valve will be reduced, resulting in the failure of the pump.

(2) the leakage of filling parts

The packing distribution of the booster pump is in the main and auxiliary functions. The leakage of the packing is mainly due to wear and tear except for the reason of the looseness of the main and auxiliary function. There are a lot of impurities in the sewage medium, and the pressure of the pressure pump can reach up to 30 mpa. Therefore, the packing is easy to leak in high temperature. In addition, the main and auxiliary functions are usually bonded together by corrosion. During the repair process, there is no special tool, which causes the damage of the main and auxiliary functions, and the added packing is easy to miss.