Leakage of valve body and bonnet
1.The casting quality of cast iron parts is not high, and there are defects such as trachoma, loose structure, slag inclusion on the valve body and valve cover body;
2.Sky freeze cracking;
3. Poor welding, including defects such as slag inclusion, non-welding, and stress cracking;
4. The cast iron valve is damaged after being hit by a heavy object.
1.Improve the quality of casting, and perform strength test strictly according to regulations before installation;
2. For valves whose air temperature is below 0 ° C and below 0 ° C, heat preservation or mixing shall be carried out, and valves that are not in use shall be drained of standing water;
3. The welding seam of the valve body and bonnet consisting of welding shall be carried out in accordance with the relevant welding operation regulations, and the flaw detection and strength test shall be performed after welding;
4. It is forbidden to push and put heavy objects on the valve, and it is not allowed to hit the cast iron and non-metal valves with a hammer.
Leakage at the packing
Leakage of the valve, the proportion of packing is the largest.
1.Wrong selection of fillers, resistance to medium corrosion, high pressure or vacuum, high temperature or low temperature resistance of valves;
2. The packing is not installed properly, and there are defects such as small generation, poor spiral coiled joints, tight tightening and loosening;
3. The filler has exceeded its useful life, has aged and lost its elasticity;
4, the valve stem is not high in accuracy, and has defects such as bending, corrosion and wear;
5. The number of packing rings is insufficient and the gland is not tight;
6. The gland, bolts, and other parts are damaged, making the gland unable to be tightened;
7, improper operation, excessive force, etc .;
8, the gland is skewed, the gap between the gland and the valve stem is too small or too large, resulting in valve stem wear and packing damage.
1.The material and type of the filler should be selected according to the working conditions;
2. Packing should be installed correctly according to relevant regulations. Packing should be compacted one by one, and the joint should be 30 ℃ or 45 ℃.
3.The packing which is too long, aging and damaged should be replaced in time;
4. The valve stem should be straightened and repaired after it is bent and worn, and it should be replaced in time if the damage is serious;
5. The packing should be installed according to the specified number of turns, the gland should be tightened symmetrically and evenly, and the compression sleeve should have a pre-tightening gap of more than 5mm;
6. Damaged glands, bolts and other components should be repaired or replaced in time;
7. Observe the operating rules, except for the impact type handwheel, operate at a uniform speed and normal force;
8. Tighten the gland bolts evenly and symmetrically. The gap between the gland and the valve stem is too small, and the gap should be appropriately increased; the gap between the gland and the valve stem is too large and should be replaced.
Leakage of sealing surface
1. The sealing surface is not ground smoothly and cannot form a close line;
2.The top of the connection between the valve stem and the closing part is suspended, incorrect or worn;
3. The valve stem is bent or incorrectly assembled, so that the closing part is skewed or misaligned;
4. The quality of the sealing surface is not selected properly or the valve is not selected according to the working conditions.
1.According to the working conditions, the materials and types of the gaskets are correctly selected;
2. Carefully adjusted and stable operation;
3. Screw the bolts evenly and symmetrically. If necessary, use a torque wrench. The pre-tightening force should meet the requirements and should not be too large or small. There should be a certain pre-tightening gap at the flange and thread connection;
4. The gasket assembly should be centered and aligned, and the force is uniform. The gaskets are not allowed to overlap and use double gaskets.
5. The static sealing surface is corroded, damaged, and the processing quality is not high. Repair, grinding, and color inspection should be performed to make the static sealing surface meet the relevant requirements. [The above contents are organized and released for you by electric actuators ]
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