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RE: ASD Torsion

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>Is there an AISC spec for torsion analysis per ASD?
There is no formal torsion specification. Torsion is normally dealt with at the stress level by calculating normal and shear stresses due to warping and pure (St. Venant) torsion, combining them in the proper locations for the maximum effects, and compring to the generalized stress interaction formulae in Chapter H (LRFD or ASD).
Torsional analysis and design is not an ASD or LRFD thing. You can do it in either method and the results are nearly identical (torsional stresses for factored loads in LRFD are normally about 1.5 times the torsional stresses for service loads in ASD, but that's also the ratio for the LRFD design stresses to the ASD allowable stresses).
>I am aware of the LRFD spec for steel hollow structural sections, but not one dealing with ASD.
The HSS Specification has only been written in LRFD. The 2005 AISC Specification, which will primarily unify LRFD and ASD, will also integrate the HSS and single-angle specifications into one document with all addressed for both LRFD and ASD.
>Does AISC design series 9 cover this?
Yes, in detail for all common structural shapes in both LRFD and ASD. Including some strategies for eliminating and minimizing torsional effects in the first place, which is the best design approach, in my opinion.