GLOBE VALVES OS & Y - FORGED - ISO 15761/API 602/B16.34
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
18
repacked without removing the bonnet, care must be taken when removing the original packing not to
scratch the valve stem sealing surface. For fugitive emission service, proprietary fugitive emission
packing must be used.
Note, PTFE has superior sealing properties compared to graphite, but is not firesafe.
Genuine APV die formed moulded low friction PTFE or graphite packing sets are recommended. A
compatible ribbon packing system or equivalent braided packing stock may be used but the emissions
will be higher. Also torque may increase. A corrosion inhibitor is recommended for stuffing box.
b) Partially unscrew gland packing nuts to reduce the compression load on the stuffing box. Remove the
stem packing.
c) Lift the gland flange/follower and gland out of the stuffing box.
d) Remove old packing as per Section 4.2.1 below.
e) APV fugitive emission graphite and PTFE packing has solid seal ring that must be cut for removal. Any
remains of existing packing must be removed from the stuffing box and stem.
4.2.1 Stem Packing Replacement & Stem Repair
First remove the valve from the line. To prevent injury ensure that all fluid and
pressure is removed from the valve both upstream and downstream before removal
and disassembly. When removing drain or stem plugs, wear protective eye masks to
avoid injury.
1. Check tightness of valve operation to serve as reference when re-tightening. Remove gland nuts and
the hook. Lift the gland up the stem clear away from the packing chamber.
2. Remove the defective packing rings with a sharp tool or packing hook. Do not scratch or score the
machined surfaces of the stem or packing chamber.
3. Examine the machined surfaces of the stem and packing chamber. Remove any scratches, scoring or
burrs with an emery cloth or by hand filing. Clean the stem with a solvent soaked rag.
Scratches to the stem and the packing chamber no deeper than 0.25mm (0.010”) can be removed by
polishing the surface with a buffing wheel. The surface finish of the packing should be Ra 3.2
µ
m and
the stem should be Ra 0.5 ~ 0.8
µ
m.
4. Count original number of rings and measure x-section thickness. If original packing cannot be counted
or measured, follow the steps below:
a) Measure the stem diameter (OD), stuffing box diameter (ID) and stuffing box depth (d)
b) Packing x-section (R)=(ID - OD)/2
c) # rings = (1.25 x d)/R
5. Install new packing. Use a genuine APV low emission, low friction packing set. If using standard coils
of packing material: cut each ring at a 45 degree angle and stagger the joints at 120 degrees, every
fourth joint will be in the same position as the first. Install rings individually using a split ring spacer,
compressing each ring by hand tigh 1/4 turns on each packing gland nut.
6. Each ring should be firmly compressed into position before the next ring is added. Rings should fit
