Globe valves are used in many industries. They are a popular choice for their versatility and easy maintenance. However, they have some common faults that can be easily solved to keep them running smoothly. In this article, we’ll look at the most common globe valve problems!
1. Valve body leakage
1) Poor casting during manufacturing, there are sand holes or cracks, resulting in reduced mechanical strength;
2) valve body welding when pulling crack.
1) the suspected cracks at the polished, 4% nitric acid solution etching, such as cracks can be shown;
2) the crack with a grinding wheel grinding or shovel to remove the cracked metal layer for welding.
2. Stem head breakage or stem bending
1)Improper operation, excessive force to close the small valve;
2) Thread with too tight or too loose;
3) too many times the operation has been used for a long time.
1) improve the operation, and avoid excessive force;
Close the valve;
2)The material of the threaded sleeve should be in accordance with the requirements, and the material should be selected appropriately;
3)Replace the valve stem again.
3. Valve cover combination surface leakage
1)The bolt tight force is not enough or tight deviation;
2) damage to the cover gasket;
3) combination surface is not flat.
1)bolt should be corner tight, tight force consistent; bonding surface clearance should be consistent；
2) replace the gasket;
3) disassembly re-examination of the bonding surface.
4. Valve flap and seat sealing surface leakage
1) not closed tightly;
2) poor grinding quality;
3) valve flap and stem gap are too large resulting in valve sagging or poor contact;
4) poor sealing surface material or impurities jammed.
1) improve the operation, re-open or close, the force must not be too large;
2) improve the grinding method, re-grinding;
3) adjust the valve flap and valve stem clearance or follow the replacement of the valve flap;
(4) re-replacement or overlay welding sealing surface, remove impurities.
5. Valve flap corrosion damage
Causes: improper selection of valve material.
1) according to the nature of the work and temperature selection of qualified valve flap material;
2) replace the valve to meet the requirements, installation should be in line with the flow direction of the fluid.
6. valve flap and valve stem from the switch failure
1) improperly repaired or not add a stop nut gasket, running due to steam, water flow, so that the bolt loosens and the bullet falls out;
2) longer running time so that the pin wear or fatigue damage.
1) According to the maintenance records to shorten the maintenance interval;
2) valve cover and stem pins to meet the specifications, and the quality of materials to meet the requirements.
7. Cracks in valve flaps and seats
1)Crack in the alloy steel joint surface overlay welding;
2) the temperature difference between the two sides of the valve is too large;
Eliminate methods: Cracks at the weld, heat treatment according to the provisions of the car light, and grinding.
8. Leakage between the valve seat and the valve body
1) assembly is too loose;
2) there are sand eyes.
Eliminate the method.
1) the seat will be removed, in the leak at the welding, and then turning process, in the embedded valve seat turning light or direct replacement of the valve seat；
2) welding on the sand hole, then turn and grind.
9. Packing leakage
1)Improper material selection of packing;
2) Packing gland is not tightened or pressed off;
3)Improper method of adding packing;
4)The surface roughness of the stem is too high or the stem becomes elliptical.
1)Select the packing that meets the requirements;
2)Check and adjust the packing gland;
3)Install the packing according to the correct method;
4) Repair or replace the valve stem.
10. The valve stem lift does not work or the switch is stuck
1) the cold state off too tight, after the heat expansion or open too tight;
2) packing pressure is too tight;
3) the clearance between the valve stem and the packing gland is too small and swollen;
4)The stem and the stem nut are damaged;
5)The packing gland is stuck tightly;
6) high temperature, the stem due to serious corrosion and poor lubrication.
1) force slowly try to open or open enough too tight and then back to open 0-5 ~ 1 turn;
2) slightly loose packing gland bolts, try to open back and forth;
3) properly expand the clearance between the valve stem and stem and packing gland;
4) Replace the stem and nut;
5)Readjust the gland bolts and tighten them evenly;
6)Adopt pure graphite powder as a lubricant for the valve passing through high-temperature working material.
In summary, the common causes of failure of globe valves are the ones listed above. To avoid these problems, you should regularly check the valve for leaks. If there are any leaks, they should be repaired immediately to prevent major damage from occurring.
TAG: elimination methods of globe valves, faults, globe valves, wesdom, wesdom valve