Analysis of mechanical seal failure

The seal.com/" target="_blank">mechanical seal is composed of at least a pair of end faces perpendicular to the axis of rotation under the cooperation of the fluid pressure and the elastic force of the compensation mechanism and the auxiliary seal to maintain and slide relative to form a device to prevent fluid leakage. Mechanical seals are widely used in petroleum and chemical companies.Due to their good sealing performance, stable performance, low leakage, low friction power consumption, long service life, little wear on the shaft (or sleeve), they can meet a variety of working conditions Requirements and other characteristics are widely used. However, its sealing structure is complicated, the use conditions are harsh, the price is high and the maintenance technology is high, especially the mechanical seal process conditions such as temperature, pressure and other process parameters directly affect the performance and service life of the mechanical seal of the equipment. Therefore, the mechanical seal is found The cause of failure and improvement measures are important tasks to ensure the safe production of enterprises and increase the service life of equipment. Do the following analysis.

Long-term phenomenon when mechanical seal fails

1.1 Screaming at work

This is because the lubrication effect of the sealing end surface is not good. The bypass flushing pipeline should be installed to increase the pipe diameter and the size of the corresponding throttling device.

1.2 The seal is popping when working

The reason is that the sealing medium is vaporized or flashed, and the pressure of the seal cavity should be increased within the allowable range, the seal design should be improved, and the medium should be reduced.

Temperature difference, install bypass flushing pipeline, increase pipe diameter and corresponding throttling element; strengthen the sealing end face cooling, check the seal balance design, accurately measure the pressure, temperature and medium pressure in the sealed cavity.

1.3 Stone grinding powder gathered outside the sealing surface

The reason is that the sealing surface is poorly lubricated, and the liquid film between the sealing end surfaces is vaporized or flashed, resulting in residual substances, causing graphite ring wear. The lubrication state should be improved to prevent vaporization.

1.4 Seal leak

Since the sealing medium is vaporized or flashed to seal the end face, the source of the leak should be judged first.The problem of cross-section sealing may be caused by uneven end face, crack, broken or blast, thermal deformation or mechanical deformation; unreasonable structure of the sealing parts or deformation due to insufficient strength; Residual deformation caused by materials and processing reasons; parts are unequally stressed during installation. Check whether the installation size is correct, whether the seal and material are suitable for use, whether the gasket is compressed, and whether the bolt torque is too large to cause deformation of the seal seat. If there is any damage to the installation, replace it if necessary; check the verticality of the packing cavity surface and other related components to the axis, and the installation error of the pipeline and equipment. "The auxiliary seal may be crushed or scratched during installation; media leaks from the gap of the sleeve , 0-ring aging; sealing compression yield deformation, chemical corrosion "Check whether the sealing groove and lead angle are normal, before starting the equipment, the sealing end face should be re-ground to ensure that the sealing face is smooth and smooth.