【2026 Conveying Machinery】Causes of Leakage in Mechanical Seals of Pumps and Countermeasures

Reasons for the failure of mechanical seals in pump machinery: Corrosion causes the failure of mechanical seals. The corrosion of mechanical seals in pump systems includes corrosion of the metal rings, corrosion of the non-metallic rings, as well as corrosion of the auxiliary sealing rings and contact areas. 1. Corrosion of the metal ring: The metal ring itself does not have corrosion resistance; it will be corroded when in direct contact with corrosive substances. In the initial stages, issues such as unusual noises, leaks, and wear may occur. Corrosion will spread inward at a certain rate. Under the action of external forces, the metal ring undergoes stress-induced deformation; the exposed areas as a result are prone to corrosion, and this corrosion gradually affects other areas through the weak points, leading to leakage in the mechanical seal.

2. Corrosion of non-metallic rings: The corrosion of graphite rings is also one of the major reasons for failures in mechanical seals. Factors such as excessively high temperatures at the interface, improper selection of impregnating resin, and insufficient depth of resin impregnation can all lead to the corrosion of graphite rings. When the graphite ring is in an oxidizing medium, and cooling is inadequate or friction occurs, temperatures of three to four hundred degrees in such an environment cause an oxidation reaction between the graphite and the oxidizing medium, resulting in the loss of performance of the end face.

3. Corrosion of the auxiliary sealing ring and contact areas Different materials have varying degrees of corrosion resistance. The material used for auxiliary sealing rings is usually elastic rubber; however, when rubber is corroded, its surface becomes extremely rough and it loses its original elasticity. Moreover, rubber has poor high-temperature resistance, generally not exceeding 200 degrees Celsius. 　　 The area in contact with the auxiliary sealing ring remains relatively stationary; gaps between the two and friction can all be causes of corrosion, and the corroded areas are generally wide and deep.

This post was last edited by The one on 2026-7-9 11:27. Fault manifestations of mechanical seals in pumps: During the production process, the leakage of mechanical seals in pumps can be attributed to both internal and external factors. The choice of materials, as well as the methods of installation and operation, can all lead to the failure of these seals. The symptoms of failure vary as well, and it is important to learn how to make accurate and timely judgments based on these different symptoms.

This post was last edited by The one on 2026-7-9 at 11:28. 1. Leakage during hydrostatic testing: During installation, carelessness on the part of the staff can often result in the sealing surfaces being damaged or deformed. Inadequate cleaning may lead to particles getting trapped between the sealing elements. Additionally, loose setting screws, insufficient compression of the gland, or low precision of the machinery can all prevent the sealing surfaces from fitting together properly, thereby causing the mechanical seal to fail and leading to medium leakage. If the sleeve is leaking, the reason may be that insufficient compression was applied to the sleeve’s sealing ring during installation, or it may not have been compressed properly; it’s also possible that the device is damaged.

2. Periodic leakage: The periodic rotation of the rotor components within the mechanical seal assembly, as well as excessive axial movement, can lead to leakage in the mechanical seal. The sealing surfaces of the mechanical seal must be subjected to certain stresses in order to function properly as seals. To meet the above requirements, the spring mechanism of the mechanical seal must have a certain degree of compression in order to apply stress to the end faces, thereby enabling the mechanical seal to achieve the desired sealing effect. At the same time, to keep the stress within an appropriate range, the pump shaft must not move much. However, in practical design, unreasonable factors often arise that result in the pump shaft moving more than expected, which has a significant negative impact on the performance of the mechanical seal.

3. Frequent leakage of mechanical seals: The frequent leakage problems caused by damage to the sealing surface include uniform circular grooves on the graphite surface of the mechanical seal, deep circular grooves formed at the cut surface of the graphite, wear on the inner edges of the graphite, wear of the steps in the graphite ring, notches on the outer edge of the graphite ring, fracture of the graphite ring, corrosion pits on the graphite ring, cracks in the cemented carbide surface, as well as burns. 　　 Common leakage problems caused by auxiliary sealing rings include end face wear and loose insert rings. 　　 Leakages caused by springs include rotor vibration, loose components, medium-related issues, and damage to the auxiliary mechanisms of mechanical seals.

4. Other mechanical seal leakage issues: In addition to the above common types of leakage, there are also cases of excessive vibration of the mechanical seal, leakage caused by pump cavitation, leakage resulting from cavitation within the seal chamber, leakage due to vaporization at the seal surface, leakage caused by excessive pump vibration, and leakage problems that occur when no flushing is provided.

Measures to address mechanical seal leakage: 1. Install fault-prevention devices. The occurrence of faults is related to actual operation and the internal structure of the machinery; certain factors can lead to faults under specific conditions. By identifying these factors, it is possible to eliminate them using fault-prevention devices. For example, an electric contact pressure gauge can be installed at the pump outlet to create a linkage between the pressure in the pump and that at the outlet; if the pressure drops, the power supply will be automatically cut off. To prevent backflow when the automatic pump stops, a check valve can be installed at the outlet of the automatic pump.

2. Improve the equipment structure: The mechanical seal has certain design flaws, and these issues increase the risk of leakage in such seals. Where conditions permit, the structure of the mechanical seal can be redesigned to minimize the risk of leakage. For example, the end faces of mechanical seals are mostly designed with a double-end face configuration; this doubles the contact area between the device and the medium, thereby increasing the risk of corrosion. From a safety perspective, the double-ended design can be modified to a single-ended sealed bellows mechanical design.