Bought a 15 gallon kettle on Facebook Marketplace. Works great, except the valve to drain the wort is up around the 4 gallon mark, which I didn’t consider until my first BIAB brew day. So far, I’m just tilting the kettle once the wort drains below the valve, but I don’t have any way to prevent the trub from transferring along with the wort.
Anyone else have this issue with their kettle? Anything I can do to make transfer out of my kettle more efficient?
Sláinte! 
Sounds like you need a dip tube. You can make one similar to this if you are so inclined:
Depending on your dimensions, you may be able to purchase one that will work for you. I have a 10 gallon Blichmann Kettle that has a dip tube that sits about 1/4" from the bottom, stir up a whirlpool by hand to settle hot break and hops in center, get nearly complete drainage.
Maybe someone with a larger kettle can comment on a better idea. 
Rad
That looks like it’ll do the trick, Rad! I was imagining something similar with heat resistant tubing, but wasn’t sure how that would hold up looking term.
Sláinte!
HERE is a link to a pic from @loopie_beer’s whirlpool setup where you can see the sediment left behind based on where he has his dip tube set.
Rad
Say, did you use some sort of heat/water resistant resin to make a water tight seal there? I’m sick of using stupid rubber O-rings that you have to get just right to prevent a leak. Would much rather glue the crap out of it and never have to worry about a leak again.
That’s not mine, just a picture for reference from google images. 
Hopefully someone who has done some of their own kettle modifications can chime in.
Rad
You could. Get a different. Ball conection and weld it in. So no more leak. This way you can create. Your own thing. So the valve sit not so high any more. Indeed you could. Use some resin as well to clue it but my thought. It could leak again and proberly gonna happen. When you got a boil going on.
I would avoid resin as resins are almost always carcinogenic and why add that factor to your brew
