(1) Use and maintain valves scientifically to reduce stem corrosion.

The gate valves used outside lack protection, and the valve stem thread is covered with sand and dust, which is easily corroded by rain, dew, frost, and snow. Add lubricating oil and grease, and check the lubrication frequently to ensure normal lubrication. Turn the hand wheel regularly to avoid the valve stem rusty and blocked.

(2) Adjust the packing gland. The pressing force of the gland on the packing should be appropriate. Under normal circumstances, the gap between the packing box and the gland is generally 0.10-0.15mm, and the gap between the valve stem and the gland is generally 0.10-0.30mm. In this way, the friction between the valve stem and the packing is minimized and good sealing performance is kept.

(3) To reduce asbestos impurities, washing with distilled water, or adding corrosion inhibitors to asbestos can reduce its corrosiveness.

(4) Improper installation of packing can also accelerate the corrosion of the valve stem, resulting in leakage of the valve stem seal. To ensure good sealing performance,

The gland should not be inclined, and there should be enough compression margin to compress the entire packing group by 30%. The pressure sleeve of the packing gland is pressed into the stuffing box to a depth of 1/4-1/3 of its height. The packing will age after a certain period of use, and the packing needs to be replaced regularly.

(5) The valve stem should have sufficient strength and willfulness, be able to withstand medium corrosion, scratch resistance, and the processing technology should be good. The surface finish should be better than ▽8 to reduce friction.

(6) The valve stem must be surface treated, such as nitriding, chrome plating or surface quenching, etc., to prevent medium leakage due to valve stem corrosion, bending deformation or surface strain.