Reynolds Wrap Up: Interpreting “Shall” vs. “Should” Statements in FEMI Standards

By John Reynolds, Principal Consultant at Intertek. December 28, 2023


Have you ever wondered what you have to do/must do/can do when you come across a “shall” statement or a “should” statement in an industry regulation, an industry FEMI standard, or even in your own internal company standards? If so, read on. This Reynolds Wrap Up is all about 50+ years of my experience with writing and interpreting “shall” vs. “should” statements in FEMI codes, standards, and regulations, as well as providing expert testimony for the legal defense of industry clients and then deciding what needs to be done. There are plenty of modal action verbs used in standards/contracts/regulations, but I will address primarily the ones labeled on the doors shown in Figure 1 that we typically deal with in order to understand all our requirements and options. Modal verbs typically show necessity, options, intent, possibility, or ability.

Figure 1. Modal Verbs Used in FEMI Standards Writing
Figure 1. Modal Verbs Used in FEMI Standards Writing

Modal Verbs Used in API and Other FEMI Standards

Let’s start with how the API uses the terms shall, should, may, and can in their published industry FEMI standards. The written forms (and I’m quoting here) used to express these provisions in API Standards are as follows:

  • Shall denotes a minimum requirement to conform to the standard.
  • Should denotes a recommendation or that which is advised but not required to conform to the standard.
  • May denotes a course of action permissible within the limits of a standard.
  • Can denotes a statement of possibility or capability.

By far, the most important aspect of this controversy is in the definition of how FEMI standards use “shall” and “should” statements, while the use of “will,” “must,” “can,” and “may” are included for the sake of completeness and understanding herein. I recognize that these modal verb terms are sometimes used interchangeably and/or incorrectly. I’m not addressing how these terms are used in formalized or informal English dialogue and other forms of documentation. I’m only addressing how they are commonly used in FEMI standards, contracts, and regulations and will likely be interpreted in a court of law when legal issues arise.

So, let’s cover what’s included behind each door in Figure 1.

What’s Behind the “Shall” Door for FEMI Standards?

As indicated above, when an industry FEMI standard tells us that something “shall” be done, that means exactly what it says in the API definitions – that it’s a minimum requirement to comply with the standard (i.e., that it is imperative/mandatory/obligatory/compulsory) and it is required in 100% of the cases – no exceptions – in order to meet the requirements of the standard wherever the word “shall” is used. “Shall” is used to indicate a clear command for action and is not permissive, optional, or just recommended. Likewise, “shall not” clearly means the indicated action/activity is prohibited under the circumstances being addressed.

Both API 510 and 570 Codes on Inspection of Pressure Vessels and Piping Systems now have over 300 shall statements in each of them. I find it useful when sites conduct first-party auditing of their own FEMI programs take a copy of each of those Codes and highlight all the “shall” statements to make sure your site can demonstrate that you are in compliance with each of the “shall” statements. That work process will best prepare your site for an eventual second-party or third-party audit or even regulatory audit. Additionally, there are now some “shall” statements in the many API RPs referenced in these two API Codes. Since these RP standards are, in fact, Recommended Practices, they are, for the most part, optional, except where mandated by the referencing Code. However, in order to claim compliance with any referenced RP standard, the owner-operator would need to comply with any included “shall” statements.

Generally, the “shall” statements are pretty much no-brainers (a slang term), meaning something that is so obvious that you do not need to think much about it (i.e., anyone who is reasonably schooled in industry FEMI practices would believe that compliance with shall statements would be necessary in order to avoid excessive risk of FEMI failures). Such “shall” statements include those from API 510, such as:

  • The owner/users shall respond to any inspection results that require corrective actions to assure the continued safe operation of pressure vessels and pressure-relieving devices.
  • An owner/user of pressure vessels shall exercise control of the vessel and pressure relief device inspection program, inspection frequencies, and maintenance and is responsible for the function of an authorized inspection agency in accordance with the provisions of this code.
  • All repairs and alterations shall be performed by a qualified repair organization.

Most knowledgeable, experienced FEMI personnel would agree with these few examples and all the other “shall” statements being obvious and mandatory for minimizing the risk of FEMI failures.

“Will” is sometimes used in place of shall, but in standards writing that I have been involved in, that substitution is discouraged, as it can cause confusion since “will” is not as clear as a “shall” statement. Most standards use the word “shall” to denote something that is a minimum requirement while reserving the “will” for simple statements about what is expected to happen sometime in the future.

What’s Behind the “Should” Door for FEMI Standards?

Similar to “shall” statements, “should” statements help to reduce the FEMI risks further and are what the FEMI SMEs who write and approve FEMI standards believe are most needed for instituting best practices to approach FEMI operational excellence [1]. As stated above in the API definitions, “should” statements in FEMI standards denote a recommendation or that which is advised but not required to conform to the standard. However, that said, there is generally a unanimous consensus in voting members on FEMI standards that following the “best practices” recommended by “should” statements is very important to achieve operational excellence, even if not required.

Hence there’s a fine line (albeit a very important line) between the use of “shall” and “should” in FEMI standardization (both in industry and company standards). If some “should” statements are vitally important 99% of the time, but there can still be reasonable alternatives and exceptions in a few cases, then a “shall” statement is not appropriate, and a “should” statement is more appropriate.

What’s Behind the “Must” Door for FEMI Standards?

Those of us involved in standards writing activities have been asked to avoid the use of the term “must” as it is most similar to a “shall” statement but is not as clear as “shall” when it comes to expressing a “minimum requirement.” API standards directors have been asking us to stop using “must” in preference to “shall” statements and requirements to avoid confusion. Hence, there are very few “must” statements left in any API FEMI standards, as we have made a concerted effort to find them and reword them into other modal verbs covered herein (i.e., mostly to “shall” statements). I still find some “must” statements in documents published by other standards development organizations, so if you find them, I recommend you treat such statements as “shall” statements.

What’s Behind the “May” Door for FEMI Standards?

A “may” statement, as indicated above in the API definitions, denotes a course of action permissible within the limits of an API standard. The word “may” is very different in meaning than the words “shall” or “should” and is generally used in relation to added helpful, informative material. “May” is generally used to indicate a permissive provision, ordinarily implying some degree of discretion by the user of the standard. The word “may” addresses optional ways of meeting a recommended practice, while “shall” addresses obligations, requirements, etc., and “should” addresses specific recommended practices. “May” clearly means something is optional or that some action is okay to accomplish something that will meet a recommended practice but is not mandatory. For example, you “may” use ultrasonic thickness testing (UTT) to record metal thicknesses during in-service inspections, or you “may” use radiography for inspecting for CUI. That means those inspection techniques are possible, yet optional, but you can still use other inspection techniques if you wish. “May” statements should not be confused with recommended practices but only as one method of complying with a recommended practice.

What’s Behind the “Can” Door for FEMI Standards?

“Can” statements are similar but a bit different than “may” statements, as indicated above in the API definitions of the two modal verbs. The two are fairly closely related relative to added informational material in FEMI standards. “Can” means that some action is possible to do – it has more to do with the ability to do something rather than permission to do something. “Can” is also used to express a possibility in place of “may.”

Both “may” and “can” have limited use in most API codes and standards but are important to understand in comparison to “shall” and “should” statements. For example, the use of “can” appears in the opening statement of API RP 572, which states: “This recommended practice (RP) supplements API 510 by providing pressure vessel inspectors with information that can improve skills and increase basic knowledge of inspection practices.” Another example using both “may” and “can” in the same sentence in API RP 572 is: “CMLs may contain one or more examination points and can be a single small area on a pressure vessel (e.g., a 2 in. (50 mm) diameter spot) or plane through a section of a nozzle where recording points exist in all four quadrants of the plane.” As indicated herein, this means the reader has permission to have more than one examination point in individual CMLs and that the user of the API RP 572 has the ability or possibility of defining a CML as a plane or a small area on a pressure vessel.

Shall vs. Should for Regulatory Compliance

For the most part, my experience as an expert witness in numerous legal defense cases in our industry is that we need to interpret the shall/should terms used in FEMI laws and regulations pretty much the same way as indicated above for industry standards. The use of a “shall” statement in regulations means that it is a mandatory requirement. “Should statements” read more as a recommendation allowing those affected by the regulations to make their own judgment about what they will do to meet the recommended practice and be ready to defend their actions where necessary. I know that some first-line government inspectors have tried to cite companies for not complying with “should” statements, but in my experience, when that happens, it typically does not stand up on an appeal.

Shall vs. Should in Internal Company Standards

In my experience over the last 50+ years, I recommend that you treat your internal company standards the same way “shall” and “should” statements are used in industry standards. Why? Because if you overuse “shall” statements in your company standards simply to encourage operating sites to do the things you really want them to do, you can create a legal trap if your operating sites aren’t aways in 100% compliance. “Shall” statements are not for getting sites to do things you really want them to do. That’s what “should” statements, along with other appropriate guidance, are for. Otherwise, if your operating site should have a bad accident (explosion, fire, injuries, etc.) and regulators or plaintiff investigators come onsite to find out what happened to find that the site was not in 100% compliance with your own “shall” statements in your own internal standards, then citations, fines, legal liability for injuries, etc. are sure to follow. I have witnessed that situation on numerous occasions. Very often, the noncompliance citations have nothing to do with the cause of the accident; but the investigators are simply looking for any and all noncompliance issues to build up their case against the owner-operator who experienced the accident.

In order to encourage/demand compliance with “should” statements in company FEMI standards, some company managements make it clear that during first- or second-party FEMI audits, they expect operating sites to be in 100% compliance with all the “should” statements in company and referenced industry standards in order to achieve a passing grade on the audit. In other words, some company management teams do not treat the “should” statements in internal company FEMI standards as optional. In that way, the company benefits by enforcing important “should” statements in internal standards without building a “legal trap” if sites are not always in full compliance with all recommended practices.

From my perspective, this section on “shall” vs. “should” in internal company FEMI standards is probably the most important part of this article. So, if I was not as clear as I intended to be, I suggest you reread it. If you are in disagreement, I would very much like to hear your thoughts.

Shall vs. Should for FEMI Operational Excellence

As I have indicated in my first book and in some previous articles on FEMI excellence, compliance with “should” statements is generally equally as important as compliance with “shall” statements [2]. Typically compliance with “shall” statements is most important from a basic common sense standpoint as well as a legal compliance perspective. However, compliance with “should” statements is most important for those seeking FEMI operational excellence, minimizing FEMI releases, and having their fixed equipment continuously available to meet the business plan [3].

In another previous article on building the three tiers of FEMI programs at operational sites, I indicated that Tier 1 was about building the basics of a strong FEMI program [4]. That is where the bulk of minimum compliance requirements (i.e., “shall” requirements) will typically be referenced. Then, in Tiers 2 and 3, the site will get into building and maintaining a lot of best practices that will help the site pursue FEMI operational excellence (i.e., seeking the goal of no significant FEMI failures).

I have previously compared FEMI compliance and operational excellence to that of climbing a ten-rung ladder in that, often, compliance with “shall” statements will only get you up to rung three or four on the ladder of FEMI excellence, whereas compliance with all “should” statements in FEMI standards/procedures will more likely get you to the top of the ladder (i.e., FEMI excellence). How far up that ladder you get is often the basic difference between compliance with FEMI minimum requirements and implementing FEMI best practices [5].

A few managers view the FEMI role at operating sites as a necessary evil or, at best, something they have to do in order to stay in compliance with rules and regulations, while they prefer to spend their budget on production improvements and other favorite endeavors. If your manager just wants FEMI compliance, they may think they do not need to seek excellence in their FEMI programs. But in my 50+ years of experience in this business, I take a very dim view of those just seeking the minimalist approach for “compliance” with minimum requirements in standards, procedures, rules, and regulations. First of all, with that approach, they rarely ever achieve or stay in compliance, whether they want to admit it or not. And secondly, minimal “compliance” is not the be-all, end-all of a successful business plan. Compliance with minimum requirements alone will rarely help you avoid all significant FEMI failures and all the loss of profit opportunities associated with them, let alone all the downtime to repair and rebuild equipment after the consequences of a significant release of hazardous material.

Summary Thoughts

Here are a few key takeaways from this article on the use of “shall” and “should” statements in industry standards, regulations, and company standards:

  • “Shall” statements are used to indicate an imperative command, indicating that certain actions are a minimum requirement in order to comply with the standard and are not permissive, optional, or just recommended.
  • “Should” statements denote a recommendation or that which is advised but not required to conform to the standard, but “should” statements should not be taken lightly as they are typically vital to the success of your FEMI program.
  • “Shall” statements are for basic minimum requirements that are an absolute necessity (i.e., no-brainers), whereas “should” statements are for recommended best practices that are more likely to lead to operational excellence in FEMI programs (i.e., fewer leaks/failures).
  • Don’t build yourself a legal liability trap for regulators and plaintiff lawyers by making actions you simply want to highly encourage into “shall” statements in your company standards; that’s what “should” statements are for.

I would be very interested if your thinking or views on the matter of “shalls” vs. “shoulds” are significantly different than mine, and if so, that you respond by leaving your thoughts in the comments section below.


  1. Reynolds, J., 2021, “How Effective Are Your BIG FIVE FEMI Risk Management Programs?” Inspectioneering Journal, 27(1), pp. 24-33.
  2. Reynolds, J., 2015, The 101 Essential Elements in a Pressure Equipment Integrity Management Program, Second Edition, Inspectioneering LLC.
  3. Reynolds, J., 2023, “The Ten Foundational Management Systems Needed to Achieve FEMI Operational Excellence,” Inspectioneering Journal, 29(4), pp. 16-24.
  4. Reynolds, J., 2014, “The Three Tiers of Most Fixed Equipment Mechanical Integrity (FEMI) Programs,” Inspectioneering Journal, 20(3), pp. 11-14.
  5. Reynolds, J., 2023, “Worst-to-First in FEMI Performance - How One Site is Making it Happen,” Inspectioneering Journal, 29(2), pp. 21-28.

Comments and Discussion

Posted by CHAD PATSCHKE on December 30, 2023
Good article, John (as usual). Here's a video I... Log in or register to read the rest of this comment.

Posted by Eric Butz on January 8, 2024 (Edited on January 8, 2024)
John, I really enjoyed your article and... Log in or register to read the rest of this comment.

(Inspectioneering) Posted by Nick Schmoyer on January 8, 2024
Hi Eric, Replying on behalf of John here to... Log in or register to read the rest of this comment.

Posted by Eric Butz on January 8, 2024
Thanks, Nick! Log in or register to read the rest of this comment.

Posted by Paul Gorman on January 9, 2024
ASME B31.3 definition "may: a term that indicates... Log in or register to read the rest of this comment.

Posted by John Reynolds on January 9, 2024
Thanks for the comment, Paul. I like it. With... Log in or register to read the rest of this comment.

Posted by Paul Gorman on January 9, 2024
Thanks John, I value and have followed your... Log in or register to read the rest of this comment.

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