The five coping technique of pneumatic valve is leaking

a pneumatic valve, pneumatic valve body and cover the leak: :. Cast iron casting quality is not high, pneumatic valve body and valve cover on the body has the defects such as sand holes, loose organization and slag. Days freezing crack; 。 Bad welding, there is a slag, no welding, stress crack defects such as; 。 Pneumatic valves are heavy cast iron after a crash damage. Methods: maintenance. Improve the quality of casting, before installation in accordance with the provisions of strength test; 。 To temperature under ° and ° pneumatic valve, should be insulated or hot, stop using the pneumatic valves should be ruled out water. Pneumatic valve body and valve cover of welding the weld, shall be carried out according to relevant welding procedures, also should carry on the inspection and after welding strength test; 。 Pneumatic valves on push heavy objects, do not allow the hammer impact non-metallic pneumatic valve, cast iron and the installation of large diameter pneumatic valve should have support.
2, filler leaks ( The packing place of pneumatic valve leakage, accounted for the proportion of largest) Choose wrong packing, no resistance to corrosion medium, not resistant to high pressure or vacuum pneumatic valve, the use of high and low temperatures; Packing installation is wrong, exist in small generation, spiral wound under joint, to tighten the loose defects such as; Insufficient packing laps, gland not compaction; Gland, bolts, and other components damaged, make gland cannot compress; Improper operation, too hard, etc. ; Gland askew, and pneumatic valve rod between the gap is too small or too large, the pneumatic valve stem wear and damage of the packing. Should be according to the working condition choose packing materials and type; According to the relevant provisions of the correct installation of packing, packing should be by circle put pressure, joint should be into ℃ or ℃; Life is too long, aging, damaged packing should be replaced in a timely manner; Pneumatic valve rod bending and wear should be carried out to the straightening, after repair, the badly damaged should be replaced in a timely manner; Packing shall be installed in a specified number of turns and gland should be symmetrical evenly the tight, pressing sleeve due mm above the preloaded gap; Damage of gland, bolts and other parts, should be timely repair or replacement; Shall comply with the operational procedures, in addition to the percussive handwheel, normal force at a constant speed operation; Should be symmetrical tighten gland bolts evenly, gland and pneumatic valve rod gap is too small, should be appropriate increase its clearance. Gland with pneumatic valve rod gap is too big, should be replaced. Three, leakage of sealing surface reasons:, sealing surface grinding, cannot form a closed line; , pneumatic valve stem and shut down a joint centers are suspended, incorrect or wear; , pneumatic valve rod bending or assembly is not straight, make close a skewed or do not meet; , sealing surface material selection of quality or not according to the working condition of pneumatic valve maintenance methods:, according to the working condition correctly select top gasket material and pattern; , the careful adjustment, stable operation; , should be symmetrically screw bolt, torque wrenches should be used when necessary, should comply with the requirements, the prestressing force is too large or small. Flange and threaded joints due and certain preloaded gap; , gasket for assembly should meet, force uniform, gaskets are not allowed to overlap and the use of double gasket; , static sealing surface corrosion and damage to the processing, the processing quality is not high, should be repaired, grinding, the examination of the color, make the static sealing surface in compliance; , installing a spacer should pay attention to clean and sealing surface application of kerosene, gaskets should not fall to the ground.
4, sealing ring link leak reason: welding, sealing ring rolling is lax, sealing ring and ontology, welding quality is poor; , sealing ring connecting thread, loose screw, compression ring; By corrosion, sealing ring connection. Methods: maintenance, sealed rolling place leakage should note adhesive rolling fixed again; , the sealing ring should be according to the welding specification to don't understand the repair welding of shi. When unable to repair welding should be cleared the original welding and surfacing processing; , unload screws, pressure washing, replacement of damaged parts, grinding seal and connection closed surface, repackaging. Of corrosion damage larger components, available methods of welding, bonding repair; , sealing ring junction surface corrosion, usable abrasive, adhesive and other methods to repair, should replace the sealing ring are used when beyond repair. Cause leaks: five, shut off:, bad operation, make close a jammed or over top dead center, joint damage fracture; , closing a connection is not strong, slacken off and fall off; , selection of fitting material is wrong, can't afford to medium corrosion and mechanical wear and tear. Methods: maintenance, correct operation, close the pneumatic valve don't too hard, cannot exceed top dead center, open the pneumatic valve pneumatic valve is fully open, the handwheel should reverse a little; , close connected to the pneumatic valve stem should be solid, thread should check the product; , closed connected with pneumatic valve stem with fasteners should withstand the corrosion of medium, and has certain mechanical strength and wear resistance.