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Re: Design for anchor bolt corrosion in refineries, etc

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Tom,

Check ASCE's "Wind Loads and Anchor Bolt Design for Petrochemical Facilities". I don't think it will have the specific information you are looking for but it may help guide you to other information sources. Section 2.4.3 under anchor bolt design section states 'there are substantial variations in corrosion rates even under relatively similar conditions'. I have personally seen this in chemical plants/refineries - some severe corrosion of steel building columns to the point where I was amazed that the structure was still standing and the columns in the next bay had relatively minor corrosion. I suspect there may have been a chlorine source nearby.

Walt Sawruk
ABS Consulting
Shillington, PA

At 04:54 PM 5/12/2005, you wrote:
What is the recommended practice, if any, for accounting for corrosion
acting on anchor bolts for industrial equipment (say, in a refinery,
chemical plant, paper mill, water towers, etc) and the effect this may have
on the bolt ("anchor rod") size?

When selecting connection bolt size for buildings and similar structures the
size is based by determining the tensile stress acting on the shank. But in
this sort of application corrosion seems to be of little concern.

Unlike anchor bolts for most building structures, those for industrial
equipment (and I am thinking specifically of tall pressure vessels and
stacks in refineries) are often subject to large tensile forces. For
industrial equipment subject to large amounts of corrosion the threaded
portions of the rod may also corrode, so it seems reasonable to size the
bolt based on the thread root area in the corroded condition.

I have seen a conflicting opinions in various published references. Maybe
not so conflicting, 'structural' references address sizing anchor bolts by
stress on the shank but do not mention anything about corrosion, texts that
address design of ASME pressure vessels size the bolts based on root area
and generally mention that corrosion is a factor.

So, what is practiced? apply a corrosion allowance to the threads and size
the bolt based on the corroded root area? size the bolt based on the
corroded shank area? Or ???


Thanks!
Tom Barsh, P.E.



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