Mechanical seal work should pay attention to the problem1

1. Special attention should be paid to avoid installation deviations during installation

(1) Tightening the gland should be carried out after the coupling is aligned. The bolts should be evenly supported to prevent the end face of the gland from being skewed. Check each point with a feeler gauge, and the error should not be greater than 0.05 mm.

(2) Check the matching clearance (ie concentricity) between the gland and the outer diameter of the shaft or the shaft sleeve, and the surrounding area should be uniform. Use a feeler gauge to check that the tolerance at each point is not greater than 0.01 mm.

a The spring compression should be carried out according to the regulations, and it is not allowed to be too large or too small, and the error is required to be 2.00 mm. If it is too large, it will increase the specific pressure of the end face and accelerate the wear of the end face. If it is too small, the specific pressure will be insufficient and the sealing effect cannot be achieved.

b. After the moving ring is installed, it should be able to spring back automatically after pressing the moving ring against the spring.

2. Precautions when disassembling

a. Be careful when installing and disassembling the mechanical seal. It is strictly forbidden to use a hand hammer and a flat shovel to avoid damage to the sealing element. If the scale cannot be removed, it should be cleaned and then removed.

b. If mechanical seals are used at both ends of the pump, take care of each other during assembly and disassembly to prevent one from losing the other.

c. For the mechanical seal that has been run, if the gland is loose and the seal moves, the dynamic and static ring parts must be replaced, and should not be re-tightened for continued use. Because the original running track of the friction pair will change after loosening, the sealing performance of the contact surface is easily damaged. Mechanical seal normal operation and maintenance issues

3. Preparations and precautions before starting

a. Check whether the mechanical seal, as well as the installation of auxiliary devices and pipelines are complete and meet the technical requirements.

b. Before starting the mechanical seal, perform a static pressure test to check whether the mechanical seal has leakage. If there are too many leaks, the cause should be found out and tried to eliminate. If it is still invalid, it should be disassembled, checked and re-installed. The general static pressure test pressure is 2~3 kg/cm².

c. Press the pump to turn the steering wheel to check whether it is brisk and even. If the cranking is difficult or does not move, check whether the assembly size is wrong and whether the installation is reasonable.

4. Installation and shutdown a. The sealed cavity should be kept filled with liquid before starting. When conveying solidified media, the sealed cavity should be heated with steam to melt the media. The crank must be cranked before starting to prevent the soft ring from breaking due to sudden start.

a. For the mechanical seal using the oil sealing system outside the pump, the oil sealing system should be started first. Stop the oil sealing system after parking.

b. After the hot oil pump is out of operation, the cooling water of the sealing oil cavity 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, so as to avoid damage to the sealing parts.

5. Operation

a. If there is a slight leakage after the pump is started, it should be observed for a period of time. If the leakage is still not reduced after continuous operation for 4 hours, the pump should be stopped for inspection.

b. The operating pressure of the pump should be stable, and the pressure fluctuation should not be greater than 1 kg/cm2.

c. During the operation of the pump, the phenomenon of evacuation should be avoided to avoid dry friction of the sealing surface and seal damage. d. The sealing condition should be checked frequently. During operation, when the leakage exceeds the standard, the heavy oil is not more than 5 drops/min, and the light oil is not more than 10 drops/min. If there is no improvement trend within 2-3 days, the pump should be stopped to check the sealing device.