What is valve packing?
What is valve packing?
Valve packing performance for wear-resistant, soft material, rich in lubricants and blocking agent, so pump packing is generally soft and lubricated.
- 1： Packing series: carbon packing, tetrafluoroethylene packing, graphite packing, high water-based packing, aramid packing, polytetrafluoroethylene slotted yarn packing, polytetrafluoroethylene packing, expanded tetrafluoroethylene packing, asbestos packing, carbon fiber packing, butter cotton yarn packing, oil impregnated cotton yarn packing, oil flax packing, canvas packing, ceramic fiber packing, nylon packing, composite fiber packing, ceramics Packing, valve packing and other products.
- 2： Various gasket series: PTFE gasket, tooth shaped gasket, asbestos gasket, ladle gasket, metal spiral wound gasket, graphite gasket, high strength graphite composite gasket, tetrafluorocarbon gasket, rubber flange gasket, asbestos manhole pad, asbestos hand hole gasket, asbestos flange gasket, etc.
- 3： Polytetrafluoroethylene products (polytetrafluoroethylene tube, rod, plate, cushion, membrane. Polytetrafluoroethylene elastic belt, etc.
- 4： Polytetrafluoroethylene coated gasket series (PTFE lined asbestos rubber packing gasket, PTFE coated non asbestos packing gasket, polytetrafluoroethylene lined asbestos rubber plate gasket, polytetrafluoroethylene lined rubber pad, condenser gasket, manhole pad, handhole gasket, PTFE lined flexible graphite composite gasket, PTFE clad metal composite gasket).
Correct installation of valve packing
Before packing installation, pay special attention to that the effective sealing of pump and valve depends on the overall condition of each component, and it is believed that the equipment requiring replacement of packing has been effectively isolated according to the site and system. The following contents are used to guide maintenance personnel, engineers and assemblers to correctly install and adjust packing.
1. The required tools need to use special tools when removing the old packing and replacing it with a new packing, and preload the gland nut with a fastener. In addition, standard safety facilities should be used frequently and relevant safety regulations should be observed. Before installation, you should be familiar with the following equipment: cutter for checking packing ring, torque wrench or wrench for calibration, safety helmet, internal and external calipers, lubricant for fastener, reflector, packing extractor, cutter for cutting packing, vernier caliper, etc.
2. Cleaning and inspection. Slowly loosen the gland nut of packing box, release all residual pressure in packing assembly, remove all old packing and thoroughly clean the packing box of shaft / rod; check whether the shaft / rod has corrosion, dent, scratch or excessive wear; check other parts for burr, crack and wear, which will reduce the life of packing; Check whether the stuffing box has excessive clearance and the eccentricity of shaft / rod; replace the parts with large defects; check the old packing as the basis for failure analysis, so as to find out the cause of early failure of packing.
3. Select packing. Ensure that the selected packing meets the operating conditions required by the system and equipment; calculate the cross-sectional area of the packing and the number of packing rings required according to the measurement records; inspect the packing to ensure that it is free from defects; ensure that the equipment and packing are clean before installation.
4. Measurement and recording. Record the diameter of the shaft / rod, the diameter and depth of the stuffing box, and record the distance from the bottom of the stuffing box to the top when sealing the ring with water.
5. Install the packing. Carefully install one packing ring at a time, and wrap each ring around the shaft or valve stem. Before installing the next ring, make sure that the ring is completely in place in the stuffing box. The next ring should be staggered, at least 90 degrees apart. Generally, 120 degrees are required. After the top ring is installed, tighten the nut by hand and press the gland evenly. If there is water seal ring, check whether the distance from the top of stuffing box is correct. At the same time, make sure that the shaft or stem can rotate freely.
6. Preparation of packing ring. Braid the packing on the shaft of appropriate size, or use a calibrated packing ring cutting machine; cut the packing into butt joint (square) or miter joint (30-45 degrees) according to the requirements, cut one ring at a time, and check whether the size is appropriate with the shaft or valve stem. Molded packing to ensure that the ring size fits the shaft or stem precisely. If necessary, cut the packing ring according to the packing manufacturer’s operating instructions or requirements.
7. Adjust packing:
- 1) Pump packing: (1) continue to tighten the gland nut by hand; (2) after starting the pump, adjust the gland nut to allow a little more leakage; (3) slowly tighten the gland nut to gradually reduce the leakage until the leakage reaches an acceptable level; (4) if the leakage stops suddenly, the gland nut should be tightened back to prevent the packing from overheating; (5) the leakage rate can be adjusted to a stable state.
- 2) Packing for valves: consult the packing manufacturer or the technical department of the enterprise for the specification of torque or compression percentage, and tighten the gland nut according to the following steps. (1) Apply torque to gland nut to 30% of full torque or compression percentage; (2) repeatedly open and close valve several times, and apply full torque when valve is in closed position;
- (3) repeat step (2) 3 or 4 times.
8. Tighten and replace again after several hours of operation. Check the adjustment of the gland and tighten it if necessary. When the gland can not be further adjusted, the packing must be replaced.
Source: China Valve Supplier: www.epowermetals.com
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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