You didn,t specify which vehicle you are using. I find the 50 ft up flatcar is useful. Still as you have an 52 ft pipe I see a problem
there. Whatever you are using you should try configuring it in surveyor. Open the Locomotve tab on the right and use the ? to open the vehicles commodity window. look at the top of each row where it will say max load 1,3, whatever. Try the max load 1 if it has one. Click on the black cross and select your pipe from the commodity list then select "load" and you will see one pipe load on the wagon. If it looks ok problem solved. if not try another row. If none of them look right you need another vehicle, lol. try the AUS flatcars.