Yes, Parallam is acceptable and durable as guide material. The manufacturer can give you certification data and/or direct you to users. The assorted certifying authorities (federal, state, provincial) in North America should be able to provide guidance as well.
Good luck. Wish I would have seen your question earlier, but I'm a new visitor to Eng-Tips.
Backfill: sorry for the late reply- we had done some testing a few years ago, but that was in the headframe only- they worked well, but from our 'investigating' we've learned that they are OK for dry shafts ( ours are not)but in wet shafts they swell up to 25%- we can't live with a swell factor like that- I think there was some hesitation from the gov't people also- I only know of one site using thenm in Canada & the grapevine talk is not very encouraging
