★ Before fixing new packing, the used packing should be removed completely with special tools, and the box of packing should be mopped clean. Observe carefully tosee if there is any part within the box of being off-centre. In case of failure to be up to the required standard, the box should be repaired or replaced.
★ Select the right packing to seal the fluid. Cut the exactly rigs with the packing cutter. If the cutter is not available, proceed as follows: the cutting length of the rings L=(shaft diameter D+ packing width S) X 1.07X ~ . In principle, for rotating shafts, to cut the packing straight in90° ;but in valves, slanted cut is more recommend, about 45°。
★ While fitting cross-sections of packing should be used for valves, preferably prepressed rings, a packing cross section with a slignt undersize (abt.0.3mm to 0.6mm)isrecommended for pumps. The required leakage gap ensures the necessary higher starting leakage for lubrication and dissipation of friction heat.
★ Cut packing rings should be installed with the cut ends staggered by 90° each layer. The rings should be carefully opened axially and radially just sufficient for them to be pushed on the shaft. If the rings are opened they can suffer damage through buckling.
★ Continue to fit rings in the stuffing box until the gland has thread available to either about 25% the packing thickness in the case of valves, or about 50% in the case of pumps.
★ In order to enhance the tight-sealing performance, it is preferential to select two or more gasket of cushion plates, and mix them for the said fixing.
★ Press the rings home with the grand and tighten the nuts by hand. In order to obtain a uniform and controlled pretension of the packing, we recommend the use of a torque wrench or a similar power measuring device.
★ Before putting into regular operation, try it under zero-load, and observe if there is anything abnormal. After putting into normal operation, it is still necessary to observe carefully to see if there is any serious leakage due to lack of compactness, or if there is sudden friction-heat and the danger of ring burning as a result of over compactness.