Editor’s Note: This is the third in a multi-part series about the Online Piping and Usage Specification (OPUS) resource available from the Mechanical Contractors Association of America (MCAA).

Long before the idea of putting a piping usage and specification resource online came to fruition, the founders of OPUS recognized the need for tradespeople to have access to what he or she wanted to know as quickly as possible in order to be able to complete their work or assignments on piping systems. The original hard copy “guideline” manual would eventually become the Online Piping and Usage Specification resource, or OPUS.