I use RectorSeal Blue +. I used to use RectorSeal #5. Our piping contractor keeps me up to speed as to what the professionals use. I hire the contractors, so they are good about helping us out in other ways. For those of us in process industries, this sealant is preferred because it works well and can be put into service immediately. Production people are impatient.
Teflon tape can be an issue. It should not be applied to the first threads at the end because it can break off and be carried down stream. Valves and other control components will end up damaged or jammed by the tape. It is difficult to troubleshoot the problem and identity the troublesome component.
Thank you,
Rich Aldrich
65 miles SE of Steve Schlumpf.
"To a pessimist, the glass is half empty; to an optimist, the glass is half full; to an engineer, the glass is twice as big as it needs to be." Unknown author