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Maintenance requirements of chemical process pump parts
Source:未知|Popularity:0|release date:2020-12-16 17:17:23
The main coupling of stainless steel pump is rigid coupling and gear coupling. 1. Rigid coupling rigid coupling is generally used on centrifugal pumps with low power. When overhauling, first remove the connecting bolt and rubber elastic ring. For the liquid with low temperature, the plane clearance between the two couplings is 2.2 ~ 4.2 mm, and when the temperature is high, it should be 1.55 ~ 2.05 mm larger than the front displacement. The diameter of rubber ring should be smaller than that of rubber ring. At the same time, special tools must be used to keep smooth and clean, and no bruises and scratches are allowed. 2. The gear coupling has good flexibility and automatic centering performance. During maintenance, the following methods are generally adopted:
a, check the meshing condition of the coupling tooth surface, the contact area along the tooth height is not less than 50%, along the tooth width is not less than 70%, there is no serious pitting, wear and crack on the tooth surface;
b, the radial runout of the outer gear ring of the stainless steel pump coupling is not greater than 0.03 mm, and the end face circular runout is not greater than 0.02 mm;
c, if the gear ring needs to be removed, special tools must be used instead of knocking, To avoid bending or damage to the shaft. When reassembling, the ring gear should be heated to about 200 ℃ and then installed on the shaft. The interference between the outer gear ring and the shaft is generally 0.01 ~ 0.03 mm;
d, when installing the intermediate extension tube or other parts, it should be assembled according to the original marks and data;
e, use the torque handle to tighten the bolts evenly.
The dynamic seal of centrifugal pump refers to the seal of impeller ring, and the radius direction should be controlled within 0.20-0.45 mm. If the clearance is too small, it is difficult to crank after assembly; if the clearance is too large, it is easy to cause pump vibration. The direction of the clearance radius between the shaft sleeve and the lining ring is generally 0.2-0.6 mm.
3. Maintenance of the static seal part of the chemical process pump includes the split joint surface of the pump body, the joint surface of the bearing gland and the bearing box, the joint of the lubricating oil system, the flange of the inlet and outlet pipes, etc. if the maintenance can not ensure no leakage, the pump can not run. The sealing of the above parts can ensure no leakage as long as the suitable adhesive and gasket are selected according to the medium. At present, the commonly used adhesive for dividing joint surface is NANDA 703 and NANDA 704.
4. impeller and rotor maintenance commonly used corrosion-resistant chemical process pump for single-stage impeller or single-stage double suction rotor. During maintenance, first check the appearance of the impeller and clean it. No matter whether it is to replace the spare parts to install a new impeller or clean the old impeller, static balance should be done after reassembly, and dynamic balance should be done if necessary. The matching of impeller and shaft adopts H / h. When installing impeller, the key and keyway should contact correctly. The allowable bending of rotor shaft diameter is not more than 0.013 mm, the maximum bending of low speed shaft is less than 0.07 mm, and the maximum bending of high speed shaft is less than 0.04 mm. The assembly of shaft sleeve and shaft adopts H / h. For the shaft of the rotor part, the radial runout of the shaft is not more than 0.013 mm, the shaft sleeve is not more than 0.02 mm, the impeller ring is not more than 0.04 mm, and the impeller end face runout is not more than 0.23 mm. The shaft diameter at both ends shall not be greater than 0.02 mm. However, for the centrifugal pump with complex structure, the above data vary according to the condition standard of the pump.
5. Maintenance of mechanical seal when repairing the mechanical seal of chemical process pump, the dynamic and static rings of the mechanical seal should be removed with special tools, and the wear of the end face should be checked. The dynamic or static balance test should be carried out for the pump rotor installed with mechanical seal, regardless of the power. In order to ensure no leakage of the seal, the static and dynamic surfaces can be pressed on the fitter platform, and water is poured to do the leakage test. If the static water does not leak, the surface roughness and flatness of the sealing surface meet the requirements. The perpendicularity deviation of end face shall not be greater than 0.015 mm during installation. The axial displacement is not greater than 0.45 mm after installation. It should be emphasized that after the mechanical seal is installed according to the requirements, it is necessary to turn the machine and check whether the cooling water part is reliable to prevent leakage or damage to the end face of the mechanical seal after rotation. The mechanical seals of pumps used in chemical plants are mostly single-stage, double-stage and series seal arrangement. However, no matter which seal arrangement, leakage is not allowed.