HF Alky unit screwed connections


PHILLIP HF alky unit licensor asks for the use of (Heavy-duty industrial-grade “extra-dense” Teflon “R” tape) on instrument screwed connections. I am investigating an incident leak through an instrument connection on an HF Alky process unit. On my investigations I concluded that maintenance people uses the same kind of Teflon in the liquid form it is a product from Chesterton called "900 Goldend paste". The leak on the screwed connection was due to corrosion on male and female screwed connection. My opinion is that Teflon tape gives more protection to the screw as it avoids the leak possibility and also gives some corrosion protection avoiding interstitial corrosion, rather than the same Teflon type in the liquid form.

I also would like from other refineries experiences in HF alky units what are the routine practices of on line inspection of screwed connections. We are thinking to start a programme of digital Rx inspection of screwed connections where practicable, according to a planning base on fluid criticality of the connection.

Please share

Regards

Luis Marques