General questions about tub drains

[Jim G -DIY]

Is there a reason why a chromed metal nut is used on PVC trap adapters. I see this on many kitchen sinks as well. I'm talking about the nut that secures the tail piece. Can you just use the PVC nut? Do these joints require a greater tightening torque and the metal one can provide this? Also, I often find some type of white sealant around the threads. Is this necessary or common practice? I don't see this on the other slip connection joints.

When using a brass drain assembly, the washer is "square" but using PVC they are tapered. From a performance and longevity perspective which is the preferred or superior method?

Thanks for any info.

 

[Terry]

You have a lot of options for connecting a kitchen sink. Chrome plated brass fittings weigh more and cost more. They also can perforate over time.
Most do have the square cut slip joint washers. I have seen chromed and unchromed nuts for these.

You can also use plastic, either the white or the black tubular fittings. I hand tighten these. I don't use pipe dope on them, they some do. I tighten the swivel on the p-trap first, as that is the interference fit that needs to center.

You can also use the glued up fittings, though it does make it harder later on to clear a drain. Some places view those as code worthy.
I plumbing where you have all of these choices. I tend to use the white tubular, which seems to last forever. They never rust through and acids don't affect them.
The kits you pick up for the trap and disposer kits will come with their own washers.