Leaking water urn

[toplondonchef]

I have a catering sized water urn that has started to leak from the threaded tap connector where it passes through the body of the urn.
Have tightened up the nuts that hold the tap to the urn and both internal and external washers are in good condition.
Have removed tap and wrapped threaded connector with plenty of PTFE tape but this seems to melt due to the high temp reached when boiling water.
Any ideas on what sealant I can use to stop the leak
Many thanks

[plumbbob]

Not sure why your PTFE tape is melting?! PTFE is used in high pressure steam equipment and will work at temperatures in excess of 200 degrees c.