Two guys are killing time messing around in an abandoned oil storage tank farm. They climb up a rusty ladder (or at least one does, can't recall) and part of it breaks off. There they are, on top of this 100 foot oil tank -- nobody around for miles -- no way down, no way to call for help -- sun is beating down on them.
Not a happy story. I think this was in a paperback collection of "macabre" stories. Can't google up the slightest trace of this story, so it's probably an obscure author.
Thanks for any clues.