Precautions during installation
1. Pay great attention to avoid installation deviation during installation
(1) The gland shall be tightened after the alignment of the coupling. The bolts shall be evenly supported to prevent the end face of the gland from deflecting. Check each point with a feeler gauge, and the error shall not be greater than 0.05 mm.
(2) Check the fit clearance (i.e. concentricity) between the gland and the outer diameter of the shaft or shaft sleeve, and make sure that it is even all around. Use a feeler gauge to check that the tolerance of each point is not more than 0.01mm.
2. The spring compression shall be carried out according to the regulations, and it is not allowed to be too large or too small. The required error is 2.00mm. If it is too large, the end face specific pressure will be increased to accelerate end face wear. If it is too small, the specific pressure will be insufficient and the sealing effect will not be achieved.
3. After the moving ring is installed, it should spring back automatically after pressing it against the spring.
Position requirements during installation
In order to ensure the stable operation, long life and low leakage performance of mechanical seal, it is very important to correctly install it on the machine. Precautions during installation:
1. Confirmation of components
When the mechanical seal is installed on the machine, it should be well compared with the general assembly drawing before installation to confirm whether the parts are ready. At this time, it should pay attention to whether there are any scars, defects and other abnormalities on the sealing surface of the seal friction pair and the seal ring, and also pay attention to whether there are scars on the shaft or shaft sleeve surface, flange and other components that contact with the packing, seal ring (O ring), etc, If any abnormality is found, it must be replaced or repaired before use.
During the actual installation, do not bring more parts than necessary to the site, so that if there are surplus parts after the installation, there is a missing part during the installation; If the parts are insufficient, it means that unnecessary parts are also assembled, which also plays the role of self inspection during installation.
(It is wrong to think that a good assembler does not need drawings and other marks. Then he is just a skilled worker, not a good repairman.)
2. Installation position
The installation essentials vary with the type of mechanical seal and the type of machine. I will not repeat it here.
Technical requirements during installation
Mechanical seal is a high precision mechanical part, and its correct installation and operation will greatly affect its service life. We generally follow the standards stipulated by the Ministry of Petrochemical Industry.
The technical requirements for the matching part of the pump with mechanical seal are as follows:
1. Shaft bending: no more than 0.05 mm at most;
2. Rotor runout: not greater than 0.06 mm near the shaft sleeve at the dynamic ring seal ring;
3. The axial displacement of the shaft is not allowed to exceed ± 0.5mm. If there is a shaft sleeve, it is not allowed to loose the shaft sleeve;
4. Alignment error of coupling: not more than 0.08~0.10mm for gear coupling (P2008C), not more than 0.05~0.06mm for elastic coupling; (customary end jump< 0.05, radial jump< 0.10)
5. The concentricity tolerance of the gland (stationary ring seat) and the seal mating lip to the shaft centerline is 0.05 mm, and the perpendicularity tolerance of the plane contacting the gasket to the centerline is 0.03~0.05 mm. If the requirements are not met, the seal cavity should be processed;
6. The end of the shaft sleeve for installing the dynamic ring seal ring and the end of the gland (or housing) for installing the static ring seal ring shall be chamfered and smoothed.
1. The mechanical seal shall be carefully installed and disassembled. It is forbidden to use a hammer or flat shovel to avoid damaging the sealing elements. If scaling cannot be removed, it shall be cleaned before removal.
2. If mechanical seals are used at both ends of the pump, take care of each other during assembly and disassembly to prevent neglect of one thing and loss of another.
3. For the operated mechanical seal, if the gland is loose and the seal moves, the moving and stationary ring parts must be replaced and should not be tightened again for further use. Because the original running track of the friction pair will change after loosening, the sealing of the contact surface is easily damaged.
2 Maintenance problems
Preparation before startup
1. Comprehensively check whether the mechanical seal, accessory devices and pipeline installation are complete and meet the technical requirements.
2. Static pressure test shall be carried out before starting the mechanical seal to check whether there is leakage of the mechanical seal. If there are many leaks, find out the causes and try to eliminate them. If it is still invalid, it shall be disassembled, checked and reinstalled. The general hydrostatic test pressure is 2~3 kg/cm2.
3. Turn the gear according to the rotation direction of the pump and check whether it is light and even. If the turning gear is hard or does not move, check whether the assembly size is wrong and the installation is reasonable.
Installation and shutdown
1. The sealing chamber shall be kept full of liquid before starting. When transporting solidified medium, the sealing chamber shall be heated by steam to melt the medium. The turning gear must be turned before starting to prevent the soft ring from breaking due to sudden starting.
2. For the mechanical seal using the external sealing oil system of the pump, the sealing oil system shall be started first. Finally stop the oil sealing system after shutdown.
3. After the hot oil pump is shut down, the cooling water of the seal oil chamber and the end face seal cannot be stopped immediately. The cooling water can only be stopped when the oil temperature at the end face seal drops below 80 degrees to avoid damaging the sealing parts.
work
1. If there is slight leakage after the pump is started, observe for a period of time. If the leakage does not decrease after 4 hours of continuous operation, stop the pump for inspection.
2. The operating pressure of the pump shall be stable, and the pressure fluctuation shall not exceed 1kg/cm2.
3. During the operation of the pump, evacuation shall be avoided to avoid dry friction on the sealing surface and seal damage.
3. The sealing condition shall be checked frequently. During operation, when the leakage exceeds the standard, the heavy oil shall not be more than 5 drops per minute and the light oil shall not be more than 10 drops per minute. If there is no improvement trend within 2-3 days, the pump shall be stopped to check the sealing device.
