stainless sanitary plug valve

[sancat]

One of our clients has asked us to fix 10 sanitary conic plug valves, which are leaking. The pressure is very low (10 psi), the liquid is very thick (cough syrup), and yet the valves leak.
The valves are supposed to have a conic plug, with a hole, and work in a similar way to a ball valve. The client insists that there has not been any Teflon jacket neither on the plug nor in the body, and that both the plug and body are made in Stainless Steel 316, however all the information I have found on the web states that some kind of sleeve is used. We have rebuilt as new both the body and the conic plug, and checked them with Prussian blue, to be sure that they are matched, and yet, we still have leaks.
Does anybody know if indeed there are conic plug valves with no sleeves?
Any advice on how to stop leakage on these valves will be much appreciated.
Thanks

sancat

 

[Q2]

I have delt with this problem in the food industry. The valves have no jacket. The best you can do is lightly grind with a buffing wheel the plug part of the valve, not the body. This will buy the cleint time to replace it with a better valve, it only a temperary fix. There have been severl food processing plant that have had to do this.

Q2

 

[sancat]

Q2,
thanks for the advice, however, these guys are not willing to replace the valves; they just want them to be fixed. However, since you do know the valves, please let me know:
Were there any kind of seals, in the pipe conection, in contact with the cone?
Was any special shaped pressing packing on the top of the cone, to ensure that the cone is always pressed?
Thanks
sancat