Exterior propane runs.

[Scott'n'Wendy]

All my previous trailers had exterior propane run in black iron pipe. GD uses rubber throughout. I'm assuming other mfrs are as well. Seems to me the black pipe would withstand the wear and tear from road debris much better. Was there a safety reason for this change? Or just $$.
Reason I ask is I am plumbing some new propane lines at camp and where I got parts said rubber lines are not for permanent runs between tank and appliance....I'm not doing that I'm using copper....but...made me think of the trailer propane lines.

[ncitro]

I would assume it's for time savings during assembly. If I recall correctly mine are stamped for RV use only.