Most Canadian and US standards have sections for terminology or definitions intended to identify the proper use of specific words within the document. In the ASME B31 series, the definitions section includes “Shall”, “Should” and “May”. The definitions of “Shall”, “Should” and “May” can also appear in the scope, as they do in the CSA Z662, to establish the expressions and implications (the intent) of the document.
In the CSA Z662, there are 4 specific types of information provided:
- Mandatory Elements (the Shalls)
- Recommended Elements (the Shoulds)
- Allowable Elements (the Mays)
- Information Elements (the Notes to Clauses)
The proper use and understanding of these words is CRITICAL (I do not believe it is possible to put enough emphasis on this) to compliant projects and operations. Because of this, we review the use of these words at the beginning of every course we teach. Without the proper understanding of these words, as defined by the document being trained, the information provided is of a lesser value.
The following is a transcript from the North American Pipeline Fundamentals course in Houston:
“…so how are we supposed to know what the intent of the document is? Both the ASME B31 series and the CSA Z662 provide us tools in the form of the wording used in each of the clauses.
In the CSA Z662 the word shall is defined as being used:
“to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard”
and the ASME B31 defines shall as:
“”shall” or “shall not” is used to indicate that a provision or prohibition is mandatory”
Now this is pretty straight forward, but remember, as “shall” clauses are mandatory and pipelines are subject to inspection and audit from various groups, including the AHJ’s, you must have documented evidence to prove you met the clause.
Now a little more complicated is “Should” and “May” clauses.
“Should” clauses are recommendations. They are however, not mandatory and as such documentation becomes a matter of good practise as opposed to the obligation created by a “Shall” clause. When you read a “Should” clause, think of the code committee saying “we strongly recommend this, but recognize you may have a situation where it is not required. I personally recommend documenting your reasons any time you choose not to follow a “Should” clause.
Now it brings us to the “May” clause. “May” is probably the most misunderstood of these words. May is a permissive. It is not a requirement and it is not a recommendation. It is permission if you need it. For most “May” clauses it is easiest to think of the code committee saying “We are not crazy about this, but recognize there can be some situations where it is required and accordingly we will allow it.” Again, my personal recommendation is that you document situations where you feel you need to use a “May” clause. There are also clauses where “May” is permission to make a choice, like “you may use red, white or blue…”
With a solid grasp on the use of these three words, establishing the intent of the various clauses of technical standards like the Z662 and the B31 series should become second nature. Don’t forget, if Simon says “shall”, you need to be able to prove it to an inspector or an auditor.