John,
The Fan Handbook from Buffalo Forge, edited originally by Dr.W.H. Carrier, has some numbers for asbestos insulation. Molded amosite with binder is given as 15-18 lb/ft3 density, which brackets the CAESARII value of 16 lb/ft3 for asbestos. The handbook also gives values for corrugated-laminated asbestos paper 4 ply (11-13 lb/ft3), 6 ply (15-17 lb/ft3) , and 8 ply (18-20 lb/ft3). Basic laminated paper density of 30 lb/ft3 gives an upper boundary value for the density of asbestos insulation. Densities for asbestos rope packing and gaskets have densities 60 to 140 lb/ft3 for dense material needing to seal. The type and amount of binder adds much to the density of raw asbestos. Another resource for density values might be the asbestos abatement contractors (Chryatech ?).
Remember to watch decimal point when inputting densities as lbs/IN3 for CAESARII. Otherwise the insulation will be heavier than the pipe, and will fall down from the supports! (And I wondered why there was over-stress condition.)
Regards, Richard Yee