Polypropylene was the pipe material of choice for concentrated (36%) HCl and
many other acids in the process industry. IIRC one of the trade mags
Process Today or some such title used to give a free chemical/corrosion
resistance chart away with their new year issue each year. A copy of such a
chart might be a useful addition to the FAQ if someone can get hold of a
current one.

Right then, hands up all those setting up a diy chemical plant in your
back garden.....


Dave