Reasons for failure of mechanical seal of stainless steel corrosion-resistant high-temperature pump
There are three reasons for the failure of the mechanical seal of the stainless steel corrosion-resistant and high-temperature resistant pump:
Stainless steel corrosion resistant high temperature pump
1 The axial displacement of the pump shaft of the stainless steel corrosion-resistant and high-temperature resistant pump is large
The sealing surface of the mechanical seal must have a certain specific pressure in order to achieve a sealing effect. This requires the spring of the mechanical seal to have a certain amount of compression to give a thrust to the sealing end surface and rotate to make the sealing surface produce the required ratio of the seal. Pressure. In order to ensure this specific pressure, the mechanical seal requires that the pump shaft can not have too much displacement, generally within 0.5 mm. However, in the actual design, due to the unreasonable design, the stainless steel corrosion-resistant and high-temperature resistant pump shaft often produces a large amount of channeling, which is very unfavorable for the use of mechanical seals. This phenomenon often occurs in stainless steel corrosion-resistant and high-temperature resistant pumps, especially in the pump start-up process, the amount of channeling is relatively large. When the balance plate is working, the axial gap b between the balance plate and the balance ring is automatically changed, thereby changing the pressure difference between the front and rear sides of the balance plate, and generating a force opposite to the axial force to balance the axial force. Due to the inertial effect of rotor movement and the fluctuation of transient pump operating conditions, the running rotor will not stand still at a certain axial equilibrium position. The balance plate is always in a state of moving left and right. The axial displacement of the balance plate in normal operation is only 0.105 ~ 0.11 mm, which meets the requirement of 0.15 mm of the allowable axial displacement of the mechanical seal, but the axial displacement of the balance plate may be possible when the pump is started, stopped, or when the working conditions are drastically changed. It greatly exceeds the allowable axial displacement of the mechanical seal. After a long time operation of the multi-stage centrifugal pump, the balance disc and the balance ring are frictionally worn. As the gap b increases, the axial displacement of the mechanical seal increases. Due to the axial force, the pressing force of the sealing surface on the suction side increases, and the wear of the sealing surface increases until the sealing surface is damaged and the sealing effect is lost. For the mechanical seal on the discharge side, as the stainless steel corrosion-resistant and high-temperature resistant pump balance plate wears out, the axial displacement of the rotor components is greater than the axial displacement required by the seal, and the pressing force of the sealing surface is reduced, which fails to meet the sealing requirements. Eventually, the mechanical seals on both sides of the pump lose their sealing effect.
2 The axial force is too large
The mechanical seal cannot bear the axial force during use. If there is axial force, the impact on the mechanical seal is serious. Sometimes the axial force is not balanced due to the unreasonable design of the axial force balance mechanism of the stainless steel corrosion-resistant and high-temperature resistant pump and the reasons of manufacturing, installation, and use. The mechanical seal bears an axial force, and the temperature of the sealing gland will be higher during operation. For polypropylene-based media, it will be melted at high temperatures. Therefore, the stainless steel corrosion-resistant and high-temperature resistant pump loses its sealing effect soon after it is started. When the corrosion-resistant high-temperature pump is stationary, intermittent spray leakage occurs on the sealing end face.
3 The deflection of the stainless steel corrosion and high temperature resistant pump shaft is too large
Mechanical seal, also known as end face seal, is a contact type dynamic seal with a rotating axis. Under the action of fluid medium and elastic elements, two seal end faces perpendicular to the axis line closely fit and rotate relative to each other to achieve The sealing effect requires uniform force between the two seals. However, due to the unreasonable design of the stainless steel corrosion-resistant and high-temperature resistant pump product, when the pump shaft is running, the deflection generated at the installation of the mechanical seal is large, resulting in uneven force between the sealing surfaces, resulting in poor sealing effect.
