I. Fault Analysis Methods for Screw Pump Seals

1. Necessity of Fault Analysis for Screw Pump Seals

Domestic and international statistics show that screw pump seal failures account for 50%-70% of centrifugal pump failures. Among screw pump seal failures, aging failures account for 10%-30%, and the vast majority are accidental failures. Accidental failures are the subject of fault analysis research.

2. Performing Fault Analysis Properly

Personnel conducting fault analysis must meet two conditions: firstly, they must possess a certain level of basic knowledge; secondly, they must have rich practical experience. In addition, they must be dedicated to their work and personally conduct in-depth on-site fault analysis.

3. Maintaining Proper Machine Pump Maintenance and Fault Analysis Records

Machine pump operation records, machine pump maintenance records, seal and fault logs, etc., should be established. Maintenance records, seal failure phenomena, failure locations, failure times and lifespans, cause analysis, and improvement measures should be recorded accurately and on time.

4. Data Collection

Correctly judge the source and conduct thorough investigation and research. This investigation process involves questioning, observing, inspecting, and necessary testing of the on-site situation. That is, collecting on-site data (including understanding and researching historical maintenance records and equipment archives), paying attention to the authenticity and completeness of the data, conducting in-depth and detailed on-site observations, and preventing subjective assumptions and one-sidedness.

5. Comprehensive Analysis

Summarize and organize the data, identify the main problems, make a preliminary diagnosis, and verify the diagnosis in maintenance practice. Understanding of faults requires a process of practice, understanding, re-practice, and re-understanding. Strive for excellence in technology, continuously improve the understanding of faults, keep records when analyzing faults, and preserve damaged seals. Common external conditions encountered during screw pump seal fault analysis can also be directly corrected or used as the direction for fault diagnosis.

When disassembling the seal, maintain the original appearance of the parts and do not damage them. Analyze and inspect all parts, clean them, and then check for wear. The main content of fault analysis is to determine the cause of the accident and formulate improvement measures by analyzing the traces, degree, and location and size of the friction pair (or wear).

II. General Fault Diagnosis Methods—Visual Inspection and Fault Judgment

The best and most important indicators of failure causes usually start with visual inspection. Once the cause is determined, the effective solution is usually clear. It must be noted that if signs or indications are lost during disassembly, they cannot be retrieved. To avoid the risk of losing key information, the following failure modes should be noted:

① External signs;
② Inspection results before disassembly;
③ Inspection results after disassembly;
④ Visual inspection results of each sealing component.

Fault analysis mainly determines the location of the fault through diagnosis (experience and testing), and then eliminates it through adjustment or replacement. Correct diagnosis is the basis for preventing and eliminating faults. Diagnosis is the process by which maintenance personnel comprehensively analyze, reason, and judge the data collected through on-site observation, inquiry, inspection, and necessary testing to reach a practical conclusion about equipment failures. It is also a process of exploring the essence of a fault through the phenomenon of the fault, raising the understanding from sensory cognition to rational cognition, and then returning from rational cognition to maintenance practice—a repetitive process of understanding.