How to deal with common failures of mechanical seals on rotating equipment

If the mechanical seal part fails, it is necessary to replace the part or improve the mechanical processing precision of the part, improve the processing precision of the mechanical seal itself and the processing precision of other parts of the pump body is very beneficial to the effect of the mechanical seal.

In order to improve the sealing effect, the smoothness and unevenness of the friction surface of the dynamic ring are higher. The friction surface of the moving ring is not very wide, usually between 2 and 7 mm.

First, the principle of mechanical seal leakage

The leakage of mechanical seal is caused by a variety of reasons, we have to deal with specific problems. In order to minimize the amount of leakage, the installation of mechanical seals must be strictly in accordance with technical requirements for assembly, but also pay attention to the following things.

1) Assembly should be clean and smooth. Mechanically sealed parts, work tools, lubricants, wipe materials should be very clean. The sealing end face of the moving ring should be wiped with a soft gauze.

2) Trim the angled rounding. Shafts, sealed end caps, etc. to be smooth trimming, shafts and end caps of the relevant fillets to be polished.

3) When assembling auxiliary seals, rubber auxiliary seals cannot be washed with gasoline and kerosene soaking, so as not to swell and deform, premature aging. After the static ring is assembled, press the compensation ring by hand to check whether it is in place and flexible; Whether the elastic opening ring is positioned reliably. Once the ring is installed, it must be guaranteed flexibility in axial movement on the shaft.

Second, mechanical seal vibration, heat treatment

If the gap between the static ring and the sealing cavity is too small, it is necessary to increase the internal diameter of the sealing cavity or reduce the rotating outer diameter, at least to ensure a clearance of 0.75mm. If the friction sub-pairing is not correct, it is necessary to change the static ring material, so that it is temperature-resistant, corrosion-resistant. This reduces vibration and heat in the mechanical seal.

Third, the pump shaft sprang a large amount of treatment

The balance device of axial force is designed reasonably to eliminate axial run-by. In order to meet this requirement, for multi-stage centrifugal pumps, the design is: balanced disc plus axial thrust bearings, by the balance plate balance axial force, from axial thrust bearings to the pump shaft axial limit.

Fourth, pump vibration treatment measures

In the manufacturing and assembly process of pump products, strictly in accordance with standards and operating procedures to carry out, eliminate vibration sources. Pumps, motors, base, field lines and other auxiliary equipment installed in the field, to strictly control, eliminate vibration sources.

Fifth, increase the auxiliary flushing system

Sealing medium in the sealing cavity contains particles, impurities, must be flushed, otherwise it will be due to crystallization, particles, impurities deposition, so that the mechanical seal spring failure, if the particles into the friction side, will lead to the rapid destruction of the mechanical seal. Therefore, the auxiliary flushing system of mechanical seal is very important, it can effectively protect the sealing surface, play the role of cooling, lubrication, washing away debris and so on.

The above is the application of mechanical seal on rotating equipment and the treatment method after failure. In the event of mechanical seal failure, we should first consider the influence factors of the mechanical seal itself, and then consider some influence factors of the external mechanical seal. For example, when analyzing the cause of mechanical seal quality accident, we should take into account the effect of other parts of the pump on the operation of mechanical seal, and take measures to continuously improve the effect of mechanical seal.