Maintenance of Sino Mechanical's F-500/F-800/F-1000 drilling mud pump
Routine inspection of the power end is the most important way of preventive maintenance. This inspection can timely detect various faults of varying sizes. For existing faults, necessary maintenance should be arranged, or the drilling rig should be repaired when it is disassembled and moved.
1. Check the preload of the main bearing bolts.
The main bearing bolts must be tightened to the following torques:
F-500 4065N.m (3000ft.lbs)
F-800 8620N.m (6360ft.1bs)
F-1000 11920N.m (8800ft.1bs)
2. Locking wire
Check all bolts (including the main bearing cap bolts and the locking wires at the heads of the crankshaft bearing baffle screws. After re-tightening the screws, the wires must be replaced. For the requirements of tightening torque, please refer to the crankshaft assembly chapter).
3. Oil pipes
Check all oil pipes to ensure that they are intact and unobstructed. Check whether the oil pump suction hose is damaged or flattened.
4. Suction filter
Check the condition of the filter and clean or replace it if necessary.
5. Main bearing cap
Remove the main bearing cap and check the tightness of the main bearing stop bolts, the condition of the bearing rollers, etc. Clean and remove any debris and foreign matter, as they will accumulate at the bottom of the bearing area.
6. Gear teeth of large and small gears
Check whether the large and small gears have abnormal wear. There will be some spots on the tooth surface during the running-in period. This is "initial pitting" and it has no effect on the life of the gear. However, during routine inspection, if the pitting continues to expand, contact the pump manufacturer immediately for a thorough inspection of the gear.
7. Crosshead pin bolts and crosshead guides
Remove the cover plate to check the crosshead pin screws and locking wire (when checking the middle crosshead pin, you can remove the rear cover and turn the connecting rod to the outer dead point). Tighten the crosshead pin bolt (No. 4 in Figure 18) to the following torque values:
F-500 120~135N.m (90~100ft.lbs)
F-800 190~205 N.m (140~150ft.1bs)
F-1000 225~240N.m (165~175ft.lbs)
Use a torque wrench and do not exceed the above values.
If the crosshead or guide plate is abnormally worn, replace it immediately. Because it may cause damage to the bearings and other parts, excessive wear will also accelerate the wear of the piston and liner.
8. Lubricating oil and oil tank
Check the oil condition and the cleanliness of the oil tank, and maintain the lubrication system according to the method described in the lubrication chapter of this manual.
9. Roller bearings
Although the basic structure of various F pumps is slightly different, they have one important thing in common - the use of roller shafts and roller bearings is a precision mechanical part. In order to ensure high service and load characteristics, the roller bearings must be carefully maintained.
Main bearing is a spherical roller bearing. The pinion shaft is mounted on a roller bearing. The eccentric bearing uses cylindrical rollers and has thrust blocks on both sides to keep the connecting rod on the center line. The crosshead pin bearing is a double-row cylindrical roller bearing. The bearings do not require special adjustment. The outer and inner rings of all bearings are assembled with very precise fits. This precision is necessary. Therefore, when the bearing is used again, the inner and outer rings and rollers must be kept together and reinstalled with the same accuracy as when they were removed.
It is often necessary to replace all faulty bearings. Even if only one part is faulty, all rows must be replaced. The movement clearance of these bearings is very small. Excessive clearance, grooves or wear on the races, and pitting or peeling of parts indicate that the bearings have failed and must be replaced as soon as possible.
All roller bearings and journals are fitted with heat (refer to the data on bearing fit for each assembly). Damaged or worn bearings or races can be knocked off the shaft with a copper rod and hammer, or removed by gas cutting, but great care must be taken not to damage the shaft. When assembling bearings, they are usually heated in an oil bath at a temperature below 149°C (300°F). The oil and oil tank must be very clean. If the oil tank is heated directly from below, the outer ring of the bearing should be padded when placed in the oil tank. The bearing should not be heated in an oil bath for more than three minutes.
Generally, do not heat the bearing with a flame, unless in special circumstances. When a flame must be used, it can only be used by an experienced welder. The flame should be at least 150m (6 inches) away from the bearing and can be tested with a temperature pen.
Do not overheat the bearing. Overheating of the bearing will cause tempering, which will soften the bearing. Once the heated bearing is installed on the shaft, let it cool naturally in place. Do not use water or other liquids to cool hot bearings. Rapid cooling will cause "heat cracking" or cracking of the inner and outer rings and rollers of the bearing, which will immediately damage the bearing.
Do not knock the bearing directly with a steel hammer. If the bearing must be knocked into place, tap it gently with a wooden hammer. Usually, lubricants are applied to the journal and mounting holes before the bearing is installed. The best lubricants for lubrication are: white lead oil - an anti-adhesion oil.
Do not remove the bearing from the packaging box before installation. Always prevent dust and foreign matter from entering the bearing. If the bearing must be cleaned, use clean kerosene or other solvents.
Pinion shaft assembly
The pinion and shaft are an integral structure, so the assembly is completed as long as the bearing and oil seal spacer are installed.
The working clearance of the bearing is pre-determined according to the accuracy of the fit installed in the shaft and bearing seat. When installing the pinion assembly on the pump, observe the following precautions:
1. Ensure that the gasket of the pinion bearing seat and the end cover gasket are correctly positioned.
2. When installing the bearing seat and end cover, the oil groove should be facing upward and aligned with the drain hole.
3. Remove the burrs, scratches and grooves on the surface of the wear-resistant sleeve, and then install the end cover in place. Be careful when assembling. When the seal lip passes through the keyway of the shaft head, prevent it from being scratched by the tip of the keyway. Also pay special attention to not allowing the seal lip to rotate on the edge of the wear-resistant sleeve when the spacer is installed in the seal.
4. Tighten the bearing cover bolts. The approximate torque is shown in the following table:
F-500 135~170N.m (100~125ft.lbs)
135~170 N.mF-800 (100~125ft.1bs)
F-1000 190 225Nm (140 165ft.1bs)
2. Check the inner and outer rings and rollers of the pinion bearing. If there are scratches, peeling, or grooves, or the radial clearance exceeds 0.20~0.25mm, it is recommended to replace the new bearing.
Check the crosshead alignment
In order for the piston to move correctly in the cylinder sleeve, the crosshead must move linearly along the horizontal axis of the frame hole. Check and adjust the crosshead alignment according to the following steps:
1. Remove the stuffing box from the mud guard, but do not remove the mud guard.
2. Place the crosshead at the front end of its stroke and carefully measure the distance between the middle tie rod and the stuffing box plate at the top and bottom using an internal caliper or telescopic bore gauge. Compare these two measurements to determine the position of the middle tie rod relative to the center line of the hole.
3. Rotate the pump to the end of its stroke and compare the measurement at the same position with the value measured at the front end to determine whether the crosshead is running on a horizontal line.
4. If the concentricity of the middle tie rod (i.e. the consistency of the piston rod axis and the longitudinal axis of the frame hole) exceeds 0.381mm (0.015") at the bottom of the mudguard hole, a gasket should be added under the lower guide plate to move the middle tie rod toward the center. If there is enough clearance between the upper part of the crosshead and the upper guide plate, the above adjustment can be made. Due to the angle of the connecting rod, the lower guide plate is heavily loaded, and its rear part is subjected to greater force, so it is also more worn. Therefore, if the guide plate can be padded firmly, it is allowed to be padded a little tilted.
During the process of adding pads, do not make the gap between the upper crosshead and the guide plate less than 0.45mm. It is allowed that the crosshead has a larger gap, which is determined by the operating characteristics of the three-cylinder pump. The pressure of the crosshead always acts on the lower guide plate.
Note: Due to power reasons, when the pump must be reversed, the pressure of the crosshead will act on the guide plate, so the guide plate gap must be controlled within 0.25~040mm range.
5. Cut the steel gasket long enough to completely pass through the guide plate. Cut the protrusion on its edge and extend beyond the frame support.
Maintenance of Sino Mechanical mud pump hydraulic end
For many years, the hydraulic end has been considered a non-consumable part because it is not like other parts that are "punctured" by liquid flushing. However, the pressure of drilling equipment has increased, which has increased the stress of the hydraulic end compared with before, and the use of corrosive mud has caused damage to the hydraulic end. However, regular and good maintenance will give the hydraulic end parts a reasonable service life.
Some major maintenance items are described as follows:
1. Make sure that all valves on the discharge side of the pump are open before the pump is working. When the valve is closed, the impact stress on the pump body will cause the beginning of fatigue cracks. At that time, cracks may not appear, but the appearance of small cracks may start the process of "corrosion fatigue damage".
2. Do not engage the clutch when the prime mover (diesel engine, electric motor and its transmission device) is running at high speed, because doing so will cause the impact load we do not want, which is not good for both the power end and the hydraulic end.
3. Properly maintain the safety valve to ensure that it can be opened when the adjusted rated pressure is exceeded (this adjustment pressure is related to the cylinder liner size).
4. When severe hydraulic impact occurs, do not use the pump for a long time.
5. Properly maintain the hydraulic end. When the pump is not used or stops running for more than 10 days, it is recommended to remove some parts of the hydraulic end such as pistons, piston rods, cylinder sleeves, etc., and thoroughly rinse the hydraulic end of the pump with clean water, wipe it clean after rinsing, and apply grease to the machined surfaces such as cylinder liner holes, valve chamber covers, gasket surfaces, valve chamber cover threads, valve seats, etc. Of course, the parts removed from the pump, including cylinder sleeves, pistons, etc., should also be protected. This not only prolongs the life of the hydraulic end by preventing corrosion, but also protects the vulnerable parts removed from the pump, keeping them in good condition so that they can be installed and used again when the pump is put into use again.
The hydraulic end assembly of the three-cylinder pump includes three forged pump heads, cylinder sleeves, valve covers and cylinder heads, suction pipes and discharge pipes. The following precautions should be observed for the maintenance and repair of the hydraulic end assembly:
1) Pump head (liquid cylinder body)
The three independent pump heads are connected to the power end frame metal to metal through stud bolts, and the power end and pump head are aligned through the holes in the power end frame and the "guide" boss located on the pump head.
However, in order to obtain accurate alignment, the grooves, burrs and dirt on the joint surfaces of the frame holes and the pump head "guide" boss must be removed, otherwise the two will be "warped" or skewed after being connected.
2) Suction pipe
The suction pipe is connected to each pump head with bolts, and the joint of the flange is sealed with an O-ring. Thoroughly clean the O-ring groove and the O-ring sealing surface at the bottom of the pump head. Put the O-ring in before installing the suction pipe. The flange must be metal-to-metal connected to ensure the sealing of the O-ring. Therefore, any nicks, grooves or punctures on the sealing surface must be repaired before installation. For repair steps, refer to the welding and repair chapter in this manual.
Before tightening the suction pipe bolts, first tighten the bolts on the three pump heads (do not tighten if loose), and finally use the torque wrench to reach the torque value.
3) Discharge pipe
The discharge pipe is tightened on each pump head with bolts and sealed with an O-ring on the joint flange. Before tightening the discharge pipe, thoroughly clean the O-ring groove and O-ring sealing surface on the pump head. A metal-to-metal connection must be formed to press the O-ring. Therefore, any nicks, grooves or punctures on the sealing surface must be repaired before installation. Refer to the welding and repair section of the manual.
Before tightening the discharge pipe bolts, first tighten the bolts on the three pump heads (do not tighten if they are loose), and then use a torque wrench to tighten the nuts connecting the pump head and the frame according to the given torque value.
4) Cylinder head flange
The replaceable cylinder head flange is bolted to the pump head surface. The cylinder head flange must form a metal-to-metal connection to ensure that its end face is perpendicular to the axis on the pump head. Therefore, make sure to remove burrs, bumps and foreign matter on the joint surface before installation.
Note: When installing the cylinder head flange, make sure its "leak hole" is at the bottom.
