Plug type stem packing on old valve

[scooter911]

I have a 60's vintage Crane 8 inch water valve with what looks to be a plug type packing gland. There is a bolt with locknut and tag that says to adjust packing tighten bolt.

Is there a special way to tighten the packing other than just tightening the bolt?

If I bottom out the packing, can I just back out the bolt and insert some regular packing and tighten back up or do I need to buy a plug type packing?

Thanks in advance

Scoot

 

[Cockroach]

Depending on the packing gland material, you can swell the seal in order to increase compression. This works well for gaskets, particularly those in the automotive industry. I would talk to a gasket manufacturer to see exactly what agent they use, it's probably hard on the packing compound.

Typically for o-ring or equivalent elastomers, which I doubt you have here, swelling leads to explosive decompression once the load is removed by disassembling the valve. This means that the seal cannot be reused. Also the swelling is uncontrollable, you may find your torques go through the roof.

With the Crane design, there is very little option to stop stem leaks other than tightening the gland bushing. This was the intent of the design. If the bolt bottoms out, simply use a shim between the bolt and packing. That's about all you can really do, sorry!

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada