codes and specs for platform on power plant stack

huangyhg

codes and specs for platform on power plant stack
i am designing a maintenance platform to be installed around a power plant stack approximately 70 feet off the ground.  as with other platforms that have been installed at differnent elevations on the same stack, i am intending on welding connection plates to the stack to support the platform.
the question i have is what applicable codes might be involved in this design?  i am aware of the obvious osha requirements for working platforms with regards to handrails, ladders, and the like.  is there anything else i should consider because the platform is on a stack, elevated, in the elements, etc?
any response is appreciated.  thank you.
the cicind code (european) on steel chimneys has a section on rest platforms.  din 4133 also described rest platforms on load and dimension etc.  
the code that applies to the design of steel structures is the aisc code. be aware of the fact that the stack is most likely hot, therefore reduced allowables should be considered.  allow for the thermal growth of the structural   
in addition to the good advice from bbird & pbonarrio, you may want to consider the general loading guidelines in asce 7.
the stresses on the stack wall may govern your design.
you will need to know the stack material, wall thickness,it's allowable stress at the design temperature, any internal design pressure and the corrosion allowance for the stack.
the "pressure vessel design handbook" by bednar has a section on local stresses in shells due to attachments.
warren.
frostrobn,
you may want to check the applicable api code for vessels and stacks.  also note, the minimum design wind load for these is 100 mph.
david
assuming the stack is in the usa, you may also want to refer to asme sts-1, steel stacks.