Hydraulic valves are an all-important component in any hydraulic system. Not coincidentally, they’re also a pain point for many manufacturing maintenance supervisors because they require routine maintenance delivered with precision and care. Those undertaking valve stem packing specifically need to do so with a mind for thoroughness as an improperly packed valve stem can lead to leakage or premature valve failure.
Prepacking tips
Correct valve stem packing begins before you remove any old packing. First, flush the hydraulic system behind the valve thoroughly and completely. This helps ensure no fluid will be present while you service the valve and that you won’t be operating in proximity to a live hydraulic system.
Making sure you have the right tooling and packing materials on hand before performing the maintenance is also important. Packing removal tools can vary in their utilities, so it’s best to determine manufacturer-specific tool requirements for each valve. Similarly, consult OEM packing material specifications to ensure you’re packing the valve appropriately.
Finally, it’s also a good idea to have a probing mirror handy to visually inspect the valve stem for any pitting or scoring after you’ve unpacked it.
The packing process
Valve stem packing is one of the first maintenance procedures a hydraulic maintenance worker learns, yet it’s one of the hardest to master. Removing old packing without shredding it or leaving debris behind can be difficult. More difficult is packing to the right density and with the right technique.
Here are a few simple tips to make packing easier and ensure better results:
- Don’t wind in new packing material. Instead, cut it into individual rings and layer the rings in. This will ensure better packing and make the packing easier to change the next time the valve stem is due for service.
- In addition to the packing material, use all-new gland studs, nuts, and washers. This will help maintain valve integrity over a longer term. Also, be sure to check bearings and replace them if needed as part of routine maintenance.
- Do not overly stuff packing material. Overpacked valve stems can result in a drop in PSI and compromised seals.
- When cutting packing material, always cut at a 45-degree angle. Right-angle cuts make it harder to seat the packing material and result in gaps when you restore pressure to the valve. Leak paths also tend to develop when packing rings aren’t appropriately cut.
Developing good habits when packing hydraulic valves leads to better performance from properly packed valves.
Proper valve stem packing benefits
Properly packed and thoroughly serviced valve stems benefit from lower leak rates, better longevity, and more consistent operation. Good valve stem packing practices and an emphasis on better quality control in routine valve maintenance are what drive these benefits.
If you notice your hydraulic valves often require repacking before manufacturer suggested guidelines, pay mind to how you’re packing them. A quick refresher and a few simple tips on proper valve stem packing can go a long way to more efficient valve operation in all your hydraulic applications.