Need to seal steel pipe with PVC pipe inside, How?

[cavitate]

I have as an example, an 8" pipe 6 feet tall, I want an inner 4" plastic pipe down the center with the plastic pipe out the bottom of the steel pipe.
There will be a another steel pipe inside the plastic pipe. The seal must be electrically insulated for High Voltage. (10kV?) I'm using the generic plastic, because whatever the tube is, it has to hold up to oils and 90*C heat, PVC won't work. The only pressure is gravity, so less than 3 PSI on the seal. I have a drawing to help understand what I want.
Thanks, Mikek

 

[cavitate]

Acetone, Hexane, bits made from plumbing parts, 90C operation, 10kV electricity....

Hope you have
A) Life insurance
B) Your garage is a long way from your house
C) A video recorder running so that investigators can see what the big bang was...

The hexane is only for cleaning between runs of different oils.
The emulsion is oil/water, I used soybean oil over the weekend.
Yep, High Voltage gets ticklish,
EDIT to add, the final assembly will have a plexiglass enclosure with a shut off switch when the enclosure is opened.
I'm also going to redesign my RED FlashingHV warning indicator, to work on AC and DC