Rotary drilling rig failure analysis is an observation, hypothesis, reasoning, verification, correction hypothesis, re-verification ... until the fault is accurately determined, it refers to the use of various logical methods, philosophical methods and mathematical methods to deduct the fault information obtained Reasoning or scientific justification to reveal the essence of a fault through the surface phenomenon.
The following editors sort out three common methods for analyzing common faults of rotary drilling rigs and share them with you.
① Analysis, induction and logical reasoning
According to the fault information, first analyze the various fault hypotheses (causes) that lead to a certain fault phenomenon (result), and then compare and verify from the possible fault hypotheses to eliminate false components and explore the true cause.
For more complicated causality, you can use the causality diagram, fishbone diagram, and fault tree to make your thinking clear and clear.
Inductive method refers to the method of deriving general conclusions from individual facts. Generally, we can only use incomplete induction method. For example, for a rotary drilling rig, the luffing mechanism does not operate, the lifting system does not operate, and the slewing mechanism does not operate. We can conclude by inductive method that the main oil pump or pilot oil pump that controls the operation of these three mechanisms at the same time is faulty. Of course, this conclusion needs to be further confirmed with other evidence.
② Proof and Rebuttal
Various fault hypotheses are tentative and have a subjective and objective conjecture. To achieve the purpose of the argument, the argument must be true and sufficient.
The individual information we obtain can only provide weak support for it. Finding negative evidence or refuting this evidence will be more powerful for fault diagnosis.
In the above example, the luffing mechanism of a rotary drilling rig does not work. One of the possible failure hypotheses is the damage of the hydraulic pump, that is: the main oil pump is damaged-the luffing mechanism does not work, but the reverse proposition is not true, and you must look for other Negative evidence, for example, that the main oil pump is damaged-the slewing mechanism cannot move, and now that the slewing mechanism is operating normally, it can be contradicted that the main oil pump is not damaged, that is, the failure hypothesis of the main oil pump failure.
③ Replacement method
The replacement method refers to the replacement of suspected failures with the same type of rotary drilling rig components in the fault diagnosis and maintenance practice of rotary drilling rigs, and a comparative analysis of the working conditions of the new and old components to determine the fault. The purpose of the part is also called the prototype replacement method. When there is no replacement condition, a similar analog signal or load can be applied to a local system or component (such as applying a specified pilot variable pressure to a hydraulic pump with a hydraulically controlled variable), and then the operating conditions can be compared and judged. When using this method, attention should be paid to the appropriateness of the new and old parts or analog signals used for replacement. It cannot be replaced blindly or the fault is expanded or a new fault is generated.