Hi Steve,

ICBO, International Conference of Building Officials creates and writes uniform building codes, which protect the public from faulty design structures and certifies all different types of inspectors by training and testing.

Maybe these two links will help get you started:

http://www.nssb.org/certapp_details.cfm?certapp_id=1015

http://www.icbo.org/About_ICBO/

Certifications apply to mechanical inspection, plumbing inspection, electrical inspection, building inspection, plans examiner, etc., or a combination.
There's an ASW-CWI ICBO home preparatory course available that requires the following publications: AWS, D1.1, AWS, D1.3, AWS, D1.4, UBC, IBC, and the AISC/ASD Manual.