The mud pump is the “heart” of the oilfield drilling system and the mud pump cylinder liner is an important wearable component of the hydraulic pump fluid end. Therefore, the life of the mud pump cylinder liner directly affects the life of the mud pump. Due to the contact with the high-temperature, high-pressure gas, the piston ring has a high-speed reciprocating motion on the surface of the cylinder ring. This determines that the cylinder liner must not only have sufficient strength and rigidity, but also must withstand high temperature, corrosion and wear damage.
Oil drilling mud pump accessories
Single metal, bimetal, ceramic, nickel based alloy.
There are several types of common mud pump cylinder liners: single metal cylinder liner, double metal cylinder liner, ceramic cylinder liner, and nickel base alloy cylinder liner.
Single metal cylinder liner
The single metal cylinder liner has the hardness of HRC58-62 after carburizing and high frequency treatment. It has the characteristics of high finish, wear resistance, corrosion resistance and long service life. It is suitable for use in milder and corrosive mud.
Double metal cylinder liner
The double metal cylinder liner is currently the most widely used and is one of the most abundant mud pump hydraulic end fittings. The double metal cylinder liner combines the advantages of hot forging high-wearing jacket and high-chromium wear-resistant and corrosion-resistant inner sleeve. The jacket is formed by hot pressing of high-quality carbon steel, and the inner sleeve is made by centrifugal casting of high-chromium cast iron. With a tensile strength of 900,000 psi, the inner sleeve has a hardness of more than HRC62 after heat treatment, and can withstand a mud pressure of 7000 psi. The inner surface is smooth as a mirror, the inner hole has a tight tolerance, and the normal service life can reach 800 hours or more.
Ceramic cylinder cover
As human beings continue to expand the range of global oil and gas resources, and become more and more severe, the replacement of a large number of metal cylinder liners is difficult to ensure the high pressure and wear requirements of the drilling rig, while the ceramic cylinder liner is zirconia and oxidized. Zirconium toughened alumina (ZTA), high performance A-99 alumina ceramics three material systems. The raw material is made of high-purity nano zirconia and alumina micropowder. It is formed by advanced cold pressing process, high temperature sintering and assembly, and finally polished by high precision. It has high flexural strength and tensile strength. Fracture toughness and acid and alkali corrosion resistance.
Nickel base alloy cylinder liner
With the continuous advancement of science and technology, nickel-based alloy cylinder liners made of new materials have been developed. The process is to coat the alloy material on the inner wall of the cylinder liner and apply vacuum sintering technology to form a 1.5mm alloy sintered layer and a sintered layer. The material is selected from high-performance rare-earth nickel-based alloy powder and a micron-sized hard alloy material is added to uniformly distribute micro-scale high wear-resistant hard spots in the sintered layer, thereby effectively improving the overall wear resistance of the sintered layer. At the same time, due to the small microstructure of the alloy, no tissue peeling occurs. Since the powder forms a good alloy sintered layer, the bonding strength is good, and the sintered layer has a Rockwell hardness of HRC: 60-64.
Compared with bimetal materials, high-performance wear-resistant and corrosion-resistant rare earth alloy powders are based on nickel. On the basis of this, due to the addition of trace elements such as C, Cr, B, Yb, Mn, Cu and rare earths, in nickel The formation of fine, dispersed and hard spots such as NiB, Cr7C3 and Cr23C6 in the matrix effectively improves the high temperature red hardness and wear corrosion resistance of the alloy, and has excellent comprehensive properties due to the action of elements such as Yb, Mn and Cu. , grain refinement, grain boundary purification, the wear resistance of the alloy is greatly improved, and the thermal shock resistance and crack resistance are improved. At the same time, the high wear resistance alloy material also enables the use of the coating. The service life is more than 2000 hours, and the maximum is about 4000 hours. It is 5-10 times that of the ordinary metal cylinder liner, which is comparable to the ceramic cylinder liner. Wear-resistant, high-temperature resistant, high-strength, high-hardness, and not easy to break. The price is far lower than the ceramic cylinder liner. The key is to improve the drilling progress and reduce the transportation, maintenance, labor, storage and other costs of drilling.
Cylinder casing processing
Introduction to the processing technology of mud pump cylinder liner
As a kind of oil drilling mud pump vulnerable parts, the mud pump cylinder liner often needs to meet the following three conditions during processing:
First: The first thing to understand is that the mud pump cylinder liner belongs to thin-walled parts. Due to the poor rigidity of the thin-walled workpiece, the cutting force and the clamping force are easily deformed during the turning process, which affects the dimensional accuracy of the workpiece. Shape accuracy. Therefore, the reasonable choice of clamping method, tool geometry, cutting amount and adequate cooling lubrication are the key to ensure the accuracy of thin-walled parts.
Second: It should be specially noted that the inner and outer circles of the part have high precision requirements, and should be thick and finely separated during processing.
Third: In addition, we must pay special attention to the fact that the mud pump sleeve is used in the final use, after the cylinder sleeve is pressed into the cylinder, the inner diameter size should be reworked again.
Mud pump cylinder liner processing process:
Coat: inspection of raw materials—-coating blank processing—-rough car outer circle—-rough car inner hole—-hot charging (and inner set for hot loading) —Fine grinding—-fine car.
Inner sleeve: centrifugal casting—-annealing—-rough car outer circle—-rough car inner hole—-semi-finishing car outer circle—-quenching—-non-destructive testing— – hot pack (hot pack with jacket).
Heat treatment method
Normalizing (removing internal stress, enhancing hardness) 800°C insulation 4-5h air cooling.
Annealing (softening) 980 ° C burning 5-6h with furnace cooling.
Quenching (hardening hardness) 980 ° C insulation 30 min air cooling.
Tempering (increased material toughness) 200 ° C for 60 min.
Hot loading: 450 ° C -500 ° C burning 5-6h, 100% full inspection, cooling after 24h pressure test .
How to prevent quenching deformation in the processing of mud pump cylinder liner?
During the operation of the oil drilling mud pump, the cylinder liner is subject to the abrasion of sand particles and the corrosive medium in the high-speed flowing mud, which is prone to failures such as strain, groove, spalling, leakage, de-cylinder and crushing. In order to improve the anti-wear and corrosion resistance of the cylinder liner, it is now formed by Cr26 high-chromium cast iron material. The blank is quenched and tempered after annealing and machining. The hardness is required to be greater than HRC62. However, due to the thin wall of the cylinder liner (6) =5.5mill, 7illm), 100% of the heat treatment has different degrees of deformation, can not meet the assembly requirements, must add shaping process, which not only increases the process cost, but also some cylinder liners are cracked and scrapped due to excessive plastic shaping. The following methods can be used to prevent mud The pump cylinder sleeve is quenched and deformed.
First: In order to prevent quenching deformation, the oil mud pump cylinder liner should adopt a lower heating temperature (980 °C) and a slower cooling rate (air cooling). When the hardness HRC>60 is required, the Cr26 high chromium cast iron material is used. The above process has a CrC ratio of 8.9 to 9.6.
Second: prevent the structure, shape and heat dissipation conditions of the basket from affecting the workpiece. The workpiece should be moved away from the basket as soon as possible to disperse the air and cool, but to avoid deformation caused by clamping under high temperature, so control the temperature range of the workpiece moving away from the basket. . Due to the repeated heating and cooling of the basket, the welded support beam on the bottom of the basket will be deformed. Therefore, the flatness of the edge of the support beam should be periodically checked and kept within the tolerance range by the process.
Matters needing attention
Things to be aware of when purchasing
When purchasing a mud pump cylinder liner, first check the standard size and drawing number of the standard cylinder liner. The cylinder liner to be installed must be the same as the standard cylinder sleeve size code. Only in this way can the standard clearance be ensured.
Things to be aware of when installing and using
First: It is strictly forbidden to throw, beat or impact the mud pump cylinder liner. If it is necessary to lay down the cylinder liner, it needs to be carried out slowly.
Second: During installation, it is necessary to ensure that the metal part of the mud pump piston and the inner wall of the mud pump cylinder sleeve are not subjected to eccentric wear as much as possible. If there is a eccentric wear phenomenon, it needs to be corrected as soon as possible.
Third: It is strictly forbidden to directly hit the cylinder liner with heavy objects such as a hammer. When hitting, it must be padded with wood and other materials, and tapped gently to cushion.
Fourth: When the equipment is deactivated for a long time below 0°C in winter, the mud in the suction chamber should be released to prevent the mud from freezing and lining the liner of the mud pump cylinder.
Eternal Bliss Alloy Casting & Forging Co.,LTD.
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