hi
you can get a u bend and a L bend pipe conector the screws onto to the ends of the pipes to join them up, they have a rubber "O" ring in them. a bit like the ones you get for copper pipes. so you have two long pipes and two "L" bend connectors and a short middle piece.
the short middle piece can be ajusted but unscrewing the pipe and pulling it out a bit, i made one years ago out of pvc piping and got the fitting in b&q where i got the pipe. cost about £7 in all. also lets you change the middle piece for a bigger piece and use it for your chipping too.
bill