PTFE Lining Inside the Tank

This sounds like something you should subcontract out; HF is toxic and absurdly dangerous. Any leak that develops will seriously endanger your workers.

TTFN (ta ta for now)
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I agree with IRstuff, this is not something you do not want to do in-house without the right kinds of expertise. HF is an extreme hazard and this coating would need to be perfect in order to avoid a very bad outcome. You should search for a contractor with extensive experience in this field to perform that task.

Andrew H.

Are you sure you need a PTFE lining?

What is HF's concentration that you are going to work with?

As per some chemical resistance tables, PE is resistant to 60% HF solution.

Either way, if you need to line an existent tank, I would consider buy a new HF resistant tank instead.
HF is a nasty, nasty chemical to work with and the last thing you want is a leak or a work accident because someone wanted to retrofit some old tank to save a few bucks.

Hi,
Safety first , you should investigate the feasibility with specialized contractors .
Consider the link attached to get advices :

I'm very surprised that you did not consider a new tank , for someone familiar with HF !!!

Good luck , HF is a very nasty product to be handle with extreme care , for the people and the environment.
Pierre