pvc
From what I read, "regular" PVC is not for food applications. You have to get uPVC or Rigid PVC (same thing I believe.) But I can't find it anywhere. Is Schedule 40 the same across Rigid and on Rigid? I'm asking can Schedule 40 sometimes be food grade NSF-51 or other non-toxic and other times refer to regular PVC with plasticizers?
Edit: Sorry. This is for Hydroponics and growing food.
Depending on how strong you want the joints, you could just push them together and leave it unglued. I've done this to create poster tubes out of 3" PVC which went through airport baggage handling just fine. PVC fittings are tapered on the inside, so the further in the pipe goes the stronger it will naturally hold.
If you want to use some glue, anything which will hold non-porous surfaces should work.
Gorilla glue makes a non-toxic PVC cement.
Best Answer
Schedule 40 is a thickness standard. Schedule 40 is thinner than schedule 80 and they are considered rigid with pipe. When you are discussing food grade it actually can be affected by the type of food. I know in some cases plastics were not allowed only stainless (years ago there may be modern plastics that can handle high acid then base ph levels other than stainless ) You would not want to use schedule 40 conduit or soil pipe for example. Knowing the type needed would help. Provide a better answer but schedule 40 is basically a pipe thickness.