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The main factors affecting the life of drilling wire rope and a scientific method for inspecting oil wire rope
Breaking accident of hoist wire rope is an important problem that has not been solved for a long time in the oil industry. Due to complex operating environment and high load application, steel cables will produce various damages such as wire breaking, wear, rust and fatigue. Without efficient and reliable safety monitoring means, damage of steel cables will accumulate over time and transform from quantitative change into qualitative change. Finally lead to the occurrence of wire rope fracture accident.
Wire rope fracture failure, mainly divided into broken wire, wear, rust, fatigue and other conditions:
1, wear broken wire: wire rope in the use process, due to the pulley, reel, hook and other objects surface contact and steel wire wear. After external wear, the diameter of the rope will become thinner, and the fine steel wire on the peripheral surface will be worn flat. The wear will become more and more serious over time, and eventually lead to broken wire. The two sides of the fracture are inclined stubble, and the fracture is flat.
2, fatigue broken wire: mainly due to the low stress damage caused by alternating load steel wire. In the actual production, the failure forms of wire rope fatigue break are the most, which are mainly divided into bending fatigue, tension fatigue, torsion fatigue, contact fatigue, vibration fatigue and so on. Its basic performance has two forms of shear fatigue caused by shear stress and positive fracture fatigue caused by normal stress. All forms of fatigue are composed of these two basic forms under different conditions.
3. Corrosion: Under the influence of environmental climate and salt spray corrosion in the working environment, lifting wire ropes in the petroleum industry are prone to serious internal corrosion. The surface of steel wire rope damaged by rust is different in oxygen affinity, which makes a local metal on the surface become the anode, and another nearby local metal become the cathode, forming a large number of small batteries. Under the action of the small battery, a number of circular corrosion pits are formed on the surface, and gradually deepened. These pits become stress concentration points, forming the source of wire rope fracture.
Due to the lack of scientific wire rope damage detection instruments, for a long time, the main detection method of drilling wire rope is still based on manual detection, manual detection because of objective reasons, there are serious "inefficient, inaccurate, high energy consumption" situation. Low efficiency, occupy a lot of operating time, reduce productivity; Inaccurate, will bring misinformation to the operating units and personnel, the formation of major safety risks; High energy consumption, not conducive to the realization of the oil industry "double carbon" goal.
Magnetic weakening measurement technology is an important innovation achievement that Chinese scientists have successfully discovered the change and motion law of space magnetic field vector situation and made great achievements in the field of wire rope detection. It takes advantage of the magnetic memory properties of ferromagnetic materials: in the structure of ferromagnetic materials, a kind of material is densely packed with magnetic domains. Each domain has a spin magnetic moment direction. If the number of domains in one direction is superior, the material will appear magnetic on a macro scale. If the direction of the spin moment in the domain is disordered, there is no magnetic performance. In its natural state, the direction of the spin magnetic moment of the magnetic domains in the wire rope is disordered, and if an external magnetic field is applied to the wire rope, it will change the number of magnetic domains in one direction in the ferromagnetic material, giving all the loading materials a moderately low order magnetic energy product, thus forming a kind of "memory field".
The weak magnetic sensor invented by TCK.W is based on the innovative principle of "spatial magnetic field vector synthesis" to modulate and demodulate the given weak electromagnetic field and form a physical field correlation relationship with the weak magnetic field information after magnetic memory planning. By extracting the memory information of ferromagnetic material with magnetic load, the defects of the wire rope can be identified quantitatively. By calibrating the characteristic information of magnetic energy potential of the normal volume element memory of the wire rope and comparing it with other volume element information extracted, the difference of magnetic energy potential caused by degeneration of the wire rope can be effectively identified. By analyzing the quantitative relationship between the physical field variable information and the corresponding mechanical bearing performance, the technical goal of wire rope quantitative detection can be realized.
The TCK.W online automatic detection technology of steel wire rope developed on the basis of magnetic weakening detection technology is an advanced technology of independent innovation in our country. Through continuous continuous detection in the process of steel wire rope operation, the safety state of steel wire rope is promoted to a higher level.
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