Graphite valve packing melted?

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Graphite valve packing melted?

Author: ihatedrips (CA)

A few months back, I replaced the packing in my ancient Crane/Repcal shower valves. The new packing washer didn't fit exactly (I have trouble sourcing these old parts) so I used the Danco graphite packing string from the hardware store to fill in the gap along the edge: [www.danco.com]

This worked great for a while. But eventually the packing on the hot side leaked. When I took it apart, everything was filled with black goo. This graphite packing seems to soften and ooze when it gets warm. The black goo was hard when cold, but easily removable after heating it up with a hair dryer.

Is this a known issue? Everything I see online claims that graphite packing has a wide temperature range. My hot water heater is set to 120F. Graphite itself has an extremely high melting point (but possibly other ingredients in the packing string do not). I'd like to understand what I did wrong.

I'm using the white PTFE packing string now, hoping for a better result.

Re: Graphite valve packing melted?
Author: packy (MA) do some reading about 120 deg hot water and legionnaiers disease.
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Re: Graphite valve packing melted?
Author: ihatedrips (CA) It's a Rinnai tankless heater with recirculation running every 15 minutes. Not sure if there's a good place for Legionella to grow in this system? AIUI the bacteria prefers still water.
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