How to properly install and adjust flexible graphite packing?

Flexible graphite packing (flexible graphite packing) is a pure graphite product made from natural squamous high carbon graphite after special chemical and physical treatment.

In addition to the excellent properties of the natural scaly graphite, the flexible graphite packing has the main characteristics of softness, elasticity, corrosion resistance, high pressure resistance, radiation resistance, and thermal conductivity.

The material of the flexible graphite packing is woven from low-sulfur expanded graphite wire, and the inner lining cotton yarn is reinforced. It has a very low coefficient of friction, does not abrade the pump shaft and stem, and has good thermal conductivity, chemical resistance and high resilience.

Flexible graphite packing has the characteristics of wide applicability, resistance to strong acid, strong alkali, high temperature resistance, long service life, self lubrication, bottom friction coefficient, etc., and is especially suitable for use under harsh media conditions.

Flexible graphite packing is made of flexible graphite composite coils. It is mainly used for the static and dynamic sealing of valves, pumps and pipe joints.

The following is used to guide service personnel, engineers, and assemblers to properly install and adjust flexible graphite packing.

First, the tools needed to remove the old flexible graphite packing replaced with a new packing root requires a special tool (packing remover), and pre-tighten the gland nut with a fastener. In addition, it is necessary to use standard safety facilities and comply with relevant safety regulations. Before use, you must first be familiar with the following equipment: Check the flexible graphite packing ring cutting machine, calibration torque wrench or wrench, helmet, inside and outside calipers, fasteners lubricant, mirror, packing remover, packing Cutters, calipers, etc.

Second, cleaning and inspection

1) Slowly loosen the fixing nut of the stuffing box and release any residual pressure in the flexible graphite packing element;

2) Remove all old flexible graphite packing and thoroughly clean the shaft/rod stuffing box;

3) Check the shaft/rod for corrosion, dents, scratches or excessive wear;

4) Check whether other parts have burrs, cracks, wear, they will reduce the life of the sealing packing;

5) Replace parts with major defects;

6) Check the old flexible graphite packing as a basis for failure analysis to find out the reasons for the early failure of the flexible graphite packing.

3. Measure and record the diameter of the shaft/rod, the bore diameter and the depth of the stuffing box. Record the distance from the bottom to the top of the stuffing box when sealing the rings with water.

Fourth, choose the right flexible graphite packing

1) Ensure that the selected flexible graphite packing should meet the operating conditions required by the system and equipment;

2) Calculate the cross-sectional area of ​​the flexible graphite packing and the number of required flexible graphite packing rings based on the measurement records;

3) Test flexible graphite packing to ensure it is free from defects;

4) Before use, make sure that the equipment and flexible graphite packing are clean.

Fifth, adjust flexible graphite packing

1) Pump the flexible graphite packing 1 and continue to manually tighten the gland nut; 2 After the pump is turned on, adjust the gland nut, allowing a little more leakage at this time; 3 Slowly tighten the gland nut,

Gradually reduce the leakage until the leakage reaches an acceptable level; 4 If the leakage suddenly stops, tighten the cap nut back and re-adjust to prevent the packing from overheating; 5 Adjust the leakage rate to a steady state.

2) The valve uses flexible graphite packing. Ask the manufacturer or technical department of the flexible graphite packing to inquire about the torque or the percentage of compression. Tighten the gland nut as follows: 1 Apply torque to the gland nut to 30% of full torque or The percentage of compression of the party; 2 repeatedly open and close the valve several times, when the valve is in the closed position, apply all the torque; 3 Repeat steps 2, 3 or 4 times.

6. Re-tightening and replacement After several hours of operation, check the adjustment of the gland and tighten it if necessary. If the gland can no longer be adjusted, replace the flexible graphite packing.