Page 236 - Root Cause Failure Analysis

224 Root Cause Failure Analysis
Precautions

The following precautions should be taken when repacking a packed-stuffing box:

Coordinate with operations control.
Observe site and area safety precautions at all times.
Ensure that equipment has been electrically isolated and suitably locked out
and tagged.

Ensure machine is isolated and depressurized with suction and discharge valves
chained and locked shut.

Installation
The following steps are followed when installing a gland:

1. Loosen and remove nuts from the gland bolts.
2. Examine threads on bolts and nuts for stretching or damage; replace if
defective.
3. Remove the gland follower from the stuffing box and slide it along the
shaft to provide access to the packing area.
4. Use a packing extraction tool to carefully remove packing from the gland.
5. Keep the packing rings in the order they are removed from the gland box.
This is important in evaluating wear characteristics. Look for rub marks
and any other unusual markings that would identify operational problems.
6. Carefully remove the lantern ring. This is a grooved, bobbinlike spool situ-
ated exactly on the centerline of the seal water inlet connection to the gland
(Figure 18-4). NOTE: It is most important to place the lantern ring under
the seal water inlet connection to ensure that the water is properly distrib-
uted within the gland to perform its cooling and lubricating functions.
7. Examine the lantern ring for scoring and possible signs of crushing. Make
sure the lantern ring’s outside diameter (O.D.) provides a sliding fit with
the gland box’s internal dimension. Check that the lantern ring’s I.D. is a
free fit along the pump’s shaft sleeve. If the lantern ring does not meet this
simple criterion, replace it with a new one.

Figure 18-4 Lantern ring or seal cage (95/96 Product Guide).