Fitting Instructions for
SUPAGRAF® PREMIER
High Performance Emission Control
Packing for Valves*
I.
For complete application details please visit the JW website:
http://www.jameswalker.biz/
Packing Installation:
1. Ensure valve is isolated and all relevant required PPE is worn to ensure a safe working
environment. Carefully remove old packing from the gland. Ensure stuffing box stem and bore are
clean and free from debris; use a solvent based cleaner to remove ingrained graphite.
Examine the stem, housing bore, gland follower and bolting for signs of wear and damage. Repair and
refurbish as required. For full housing recommendations, please consult JW brochure “Improving Valve
Sealing Performance and Emissions Control” pp 14-15. These would include a max radial extrusion
clearance of 0.2mm and a stem surface finish between 0.4-0.6 μmRa.
Measure the valve stem and gland diameters as well as the depth of the gland, so the correct sized packing
ring can be chosen. The packing section (S) is calculated by:
S= (Housing Bore Diameter – Valve Stem Diameter) / 2
2. JW recommends between 5 and 6 rings of packing for optimum performance. In order to
accommodate the recommended number of compression packing rings (5-6), as well as the gland
follower entry into the stuffing box, the overall packing space (A) should be:
7.5S +L ≤ A ≤ 8.5S +L
Where:
L is the length of the lantern ring/spacer.
(Location of ring does not affect the formula.)
S is the section of the compression packing
ring
If the gland is deeper than this, it should be fitted
with a bushing to reduce he excess depth. (The
bush should be made from a suitable material for
the process conditions, such as stainless steel,
phosphor bronze, hard carbon, etc.)
3. Ensure bolt threads are clean before use. Lubricate threads with an appropriate lubricant, suitable
for the required temperature range and application, before applying any load.
The information contained in this transmission is intended for the person(s) named above. It may contain
privileged information and if you are not the intended recipient you must not copy or distribute or take any action
in relation to it. If you have received this in error please notify us immediately by telephone and return the original
by post.
Thank you.
II.
Rings Cut From Length Form Packing:
4. Rings produced from length form packing should be cut by spirally
wrapping the packing around a spare stem or mandrel of the same
diameter and subsequently cutting axially along the stem, using a sharp
knife, to produce rings with a butt join.
*Compression packing is supplied as preformed rings and sets or boxed in
8m lengths.
III.
Ring Installation (For Preformed Rings And Rings Cut From Length):
5. Install the rings individually, by partially entering the ends together into the gland, before inserting
the remainder of the ring. The join should be fitted first, followed by the portion of the ring 180°
from it. Subsequently fit the two points at 90° from the join. The ring should be tapped firmly to
the bottom of the housing, using the follower and/or distance piece as required.
6. Ensure rings are fitted in such a way that the join points of adjacent rings are staggered by 90° to
180°.
7. Fit the first two (2) rings of packing into the stuffing box, as described in section 7, pressing each
ring firmly into the base of the housing. A split extension to the follower may be required as
discussed in section 7. Compress the rings to the full recommended torque (100%), using a
calibrated torque wrench to the pre-determined bolt torque, to generate the pre-determined axial
stress in the assembly (see Section IV: Bolt Load Calculation)
8. Continue by fitting the next two (2) rings as described in section 7. Compress with 100% of the
pre-determined bolt torque.
9. Subsequently fit the remaining rings (1-2) as described in section 7 and compress with 100% of the
required torque.
Before system pressure is applied, in order to maximise the performance of the packing set, 10-20
bedding in/settling cycles at increasing torque levels are required, as described in the sections
below:
10. Unload the full packing set completely (back off). Compress the packing set with 25% of the predetermined torque applied on the bolts and carry out 10-20 bedding in cycles. Re-apply the torque
at the top and bottom of each stem stroke.
11. Compress the packing set with 50% of the pre-determined torque applied on the bolts and carry out
10-20 bedding in cycles. Re-apply the torque at the top and bottom of each stem stroke.
The information contained in this transmission is intended for the person(s) named above. It may contain
privileged information and if you are not the intended recipient you must not copy or distribute or take any action
in relation to it. If you have received this in error please notify us immediately by telephone and return the original
by post.
Thank you.
12. Finally, compress the packing set with the full pre-determined torque (100%) applied on the bolts
and carry out 10-20 bedding in cycles. Re-apply the torque at the top and bottom of each stem
stroke.
13. In the event that a sub-zero thermal cycle will be carried out, it is advised that additional beddingin cycles and/or retightening of the bolts at the low temperature conditions are carried out, to help
consolidate the packing, increase packing friction, reduce fugitive emissions performance and
stopping water ingress.
IV.
Bolt Load Calculation:
To deliver leakage performance associated with fugitive emission standards such as ISO 15848-1, it is
recommended that a compression stress between 50-70 MPa is applied to the compression packing.
Please note that this stress value could vary up to 100MPa for certain applications.
The following formula can be used to calculate the required bolt torque to achieve a 70MPa stress:
T=
(B2 – C2) x D
Where: T is the required torque, measured in Nm. N is the number of bolts.
D is the bolt diameter, measured in mm. B is the Housing Bore diameter, measured in mm.
C is the Valve stem diameter, measured in mm.
The information contained in this transmission is intended for the person(s) named above. It may contain
privileged information and if you are not the intended recipient you must not copy or distribute or take any action
in relation to it. If you have received this in error please notify us immediately by telephone and return the original
by post.
Thank you.