compression female connectors with no washers on kitchen tap

[tonton]

My kitchen tap was connected to fittings that look like the attached picture. There was a lot of what looked like PTFE tape on the tap's threads, but no washer at the bottom of the threads / in the fitting. What is the correct way to fit this type of connector?

 

[Deleted member 267285]

Ptfe tape can be used, preferred method is fibre washer.

 

[Jackrae]

That has a parallel thread so designed to seal against a flat face, Use of tape is a bodge, there should be a fibre washer.

 

[tonton]

That has a parallel thread so designed to seal against a flat face, Use of tape is a bodge, there should be a fibre washer.

My fittings have nuts with flat faces, that picture is just the most similar-looking thing I could find online. How can you tell if a fitting has non-parallel thread, is it obvious?

 

[polesapart]

 

[tonton]

The fitting was parallel threaded. The threads are internal and there are only 10mm of them, I used calipers to check. They looked like they had a seat for a washer, I read that non-parallel threaded fittings won't always include that. I also read that there aren't any non-parallel threaded female brass fittings? Anyway, PTFE had worked for many years, but I'll go for fibre washers as well. Thanks for the help.

 

[Madrab]

Sometimes with these fittings regardless of the thread type, the male fitting doesn't reach all the way to the bottom, therefore using a washer doesn't always work. Regardless of the thread type, I always use some Gas PTFE tape, hasn't failed me yet.