pre-soaking teflon packing

[BoilerOps]

when I was in Naval service, we used to pre-soak teflon packing for pre expansion before installation into stuffing box. And it appears that this is no longer a need or never has been. Is there a need to pre-soak teflon rope packing prior to installation to reduce burnout?

 

[JJPellin]

I would still pre-soak any packing. Even if the packing material is not prone to absorb water, it will fill with water between the fibers and swell slightly. Properly soaked, it will provide a better result with lower leakage and less chance to burn up on start-up.

Johnny Pellin

 

[Artisi]

Having been round pumps most of my working life so guess I have either packed, set the policy for or been indirectly responsible for the packing of many thousands of pump stuffing boxes but never once have I pre-soaked the packing. I have also packed quite a number of stern tube stuffing boxes in my day where each turn of packing was coated with water-proof grease as it was fitted but not pre-soaked.

 

[JJPellin]

Artisi,

Your statements are powerful. But, they say nothing about the value of soaking. All you have said is that you have never tried it. And, it is implied that you have had good results. On the other hand, I have tried it both ways on our largest packed pumps. And, I believe that soaking the packing produces better results. The original post says nothing about the application. So, I should note that my experience is only relevant to the stuffing boxes of pumps in water service where the packing is lubricated with the pumped product. I cannot address any other applications.


Johnny Pellin

 

[Compositepro]

I'm not familiar with presoaking. What are the supposed benefits? Any water trapped in the packing will slowly leak-out and reduce compression. Is that good, perhaps?

 

[JJPellin]

I think the theory would be that the first time packing is exposed to product, it will swell slightly. If the packing is installed dry and given an initial adjustment before it is fully saturated, it could swell slightly resulting in inadequate leakage and the possibility of burning up or glazing over. Especially with Teflon packing, once it is glazed over, it will never seal properly again, no mater how it is adjusted. I probably came across as harsh with my first reply directed at Artisi. On further thought, I might state my case differently.

There is no doubt that a skilled and experienced person can install packing dry (or coated in grease) and get excellent results. It may involve a very careful packing technique. It may involve a period of operation and adjustment at various times after start-up. But, in my experience, these skills are harder and harder to come by. And spending the time to make multiple adjustments over time is harder and harder to justify. It may be that packing that was soaked before installation could be installed with slightly less skill and less adjustment during initial run and still achieve very good results. Perhaps it is saying that you could get about the same outcome, but get it faster and cheaper with a less skilled workforce. And, I include myself under that category of less skilled. I have personally packed our largest water pump with Teflon packing that had not been soaked and had the packing smoke on start-up. Installing packing is one of those things that is harder to do well than it first appears. And, by soaking the packing before installation, I have been more successful with less time and effort.


Johnny Pellin