【正文】 if must now be opened, the valve cover is screwed loose half circle to the circle, eliminating stem stress, then moving the hand wheel plate.( two) noteIn 1, more than 200 DEG C high temperature valve, because the installation at room temperature, and after normal use, temperature rise, heat expansion bolt, increase a gap, so must be tightened again, called hot tight, the operation staff should pay attention to this work, otherwise prone to leaking.In 2, when the weather is cold, the water valve closing stop valve should be long, after removing ponding. Steam valve steam stop, also to drain condensed water. The bottom of the valve as the plug, it can be open drainage.In 3, a metal valve, some hard and brittle, some low intensity, operation, opening and closing force can not be too large, especially not so fierce. Also note that monarch free object collision.In 4, the new valve when in use, packing pressure should not too tight, not leakage, so as not to stem pressure too big, accelerate wear, and open and close it.。t let the flange joint surface in contact with the ground. This not only in appearance, is mainly protects the valve from damage. The safekeeping and improper handling, hand wheel broken, stem touch askew, the handwheel and the stem of the fixed nut loose loss etc, these unnecessary losses, should avoid. On the short term not used valves, should remove the asbestos packing, in order to avoid electrochemical corrosion, damage to the valve stem. Just into the library of the valve, to check, such as during transport into the water or dirt, to wipe clean, and storage.、The valve import and export use waxed paper or plastic sheet to seal, to prevent in dirty things.、On the energy in the atmosphere rusted valves processing surface antirust oil, to protect.、Outside of the valve, must be covered with linoleum or tarpaulin, rainproof, dustproof articles. Warehouse storage valve should be kept clean and dry.、( two) the use of maintenance、The purpose is to use and maintenance, prolonging the service life of the valve and assure reliable opening and closing.、Threaded stem, often with a stem nut friction, to apply a little oil or graphite, molybdenum disulfide, Huang Gan, play the role of lubrication. Not frequent opening and closing valves, also to regularly rotate the handwheel, the stem threads add lubricant, in order to prevent the bite. The outdoor valve, to stem with protective sleeve, with rain, snow, dust, rust. Such as valves machinery to move, to the gearbox to add lubricating oil. To keep the valve cleaning. Always check and keep the valve parts integrity. If the hand wheel fixing nut off, to plete, cannot use makeshift, otherwise it will Mill Park the upper valve stem Quartet, gradually lost with reliability, can39。 cold insulation materials are cork, perlite, foam, plastic etc.. Without water, steam valve must be drained water.( four) bypass and instrumentSome valves, except for the necessary protection facilities, but also has a bypass and instrument. Install bypass, convenient drainage valve maintenance. Other valves, also install bypass. Whether to install bypass, to see the valve status, importance and the requirements of production and.( five) packing replacementStock valve, some packing has been not so, some with the use of dielectric mismatch, which requires the replacement of packing.Valve factory is unable to consider the use of units of thousand doors million class in different media, the stuffing box is always filled with a mon root, but when in use, must let the filler and the medium is adapted to.In the replacement of the stuffing, to a circle press. Each lap joint with 45 degrees appropriate, ring and ring seam stagger 180 degrees. Filler height to consider gland continue pressing room, now to cover lower pressure packing chamber proper depth, the depth the general for the packing chamber total depth of 1020%.For the high requirements for the valve, joint angle of 30 degrees. Circle and circle seam stagger between 120 degrees.In addition to the filler, can also be based on specific circumstances, adopt rubber O ring ( natural rubber resistant to 60 degrees Celsius below weak base, acrylonitrile butadiene rubber resistant to 80 degrees Celsius below oil, fluorine rubber resistant to 150 degrees Celsius below various corrosive medium ) three stacked PTFE ring ( resistant to 200 degrees Celsius below the strong corrosive medium ) nylon bowl shaped ring ( resistant to 120 degrees Celsius below ammonia, alkali ), forming filler. In ordinary asbestos packing outside, coated with a layer of Teflon belt, can improve the sealing effect, relieve stem electrochemical corrosion.In packing, valve stem to rotate at the same time, in order to keep around evenly, and to prevent too much death, tighten the cap evenly, Do not tilt.Section second maintenanceOn valve maintenance, can be divided into two kinds of circumstances。 even if the installation of temporary difficulties, but als