1:144 industrial handrails and stairs

Your best bet would likely be model railroad or architectural model suppliers. For the former, you might have to go N scale -- 1/160, not an exact match but often visually compatible with 1/144. For the latter, try suppliers like Plastruct and Evergreen...although for architectural model fittings, 1/100 is a much more likely standard scale.

Cheers

I was going to second the N-scale (1:160 in US) recommendation and call out Loren Perry's Gold Medal Models.  But I'm not sure that what he has will fill your bill.   For stairways he has several fire escapes  http://goldmm.com/nscale/gmnsfesc.htm  He does offer industrial rails and stairs (no pictures)

A problem with 160 scale details on a 144 scale subject is that they will appear 10% small