“Meetings should have as few people as possible, but all the right people.”  — Charles W. Scharf

Ever been in a Process Hazard Analysis (PHA) meeting where there were over a dozen people? Wasn’t it excruciating? Either you wondered why you needed to be there, or you wondered why some of the other people needed to be there. How many should participate in a PHA meeting?

It’s possible for there to be too few. More often though, there are too many.

One Is the Loneliest Number

Many of the PHAs that get done are required as part of complying with the Process Safety Management (PSM) standard, 29 CFR 1910.119. The PSM standard requires a PHA for each covered process.

The PSM standard requires that a PHA “…be performed by a team…” OSHA has made it clear that when it calls for a team, there must be at least two people involved in the effort. So, one person cannot perform a PHA by themselves, even if they know everything that needs to be known about the process being reviewed.

Is Two Enough?

In Appendix C to §1910.119—Compliance Guidelines and Recommendations for Process Safety Management (Nonmandatory), OSHA offers this advice about the size of PHA team: “A PHA team can vary in size from two people to a number of people with varied operational and technical backgrounds.” So, two might be enough, as long as the two of them fulfill the PSM regulatory requirements for a PHA team.

What are the regulatory requirements? There are four. Three come from paragraph (e)(4) on Process hazard analysis:

  1. Expertise in engineering and process operations.
  2. At least one employee who has experience and knowledge specific to the process being evaluated.
  3. One member of the team must be knowledgeable in the specific process hazard analysis methodology being used.

One way to think about the first two requirements is that OSHA requires that someone in the PHA understand how the process is supposed to work and that someone in the PHA understands how the process actually works.

The last comes from paragraph (c)(2) regarding Employee participation:

  1. “Employers shall consult with employees and their representatives on the conduct and development of process hazards analyses…”

Keep in mind that when OSHA refers to “employees”, they mean hourly employees. Engineers and production supervisors? OSHA considers them to be “employer representatives.” OSHA never explicitly states that hourly employees must be part of a PHA team, but many organizations have concluded that the easiest way to show that employees have been consulted “on the conduct and development of process hazard analyses” is include at least one operator on the PHA team.

Is it possible to satisfy all four requirements with a team consisting of just two people? Rarely. One possibility, however, is to form a team consisting of a very experienced operator who has extensive knowledge of the process being evaluated (satisfying requirements 2 and 4) and a process engineer for the process being evaluated who is also trained as a PHA facilitator for the PHA methodology being used (satisfying requirement 1 and 3).

Something that complicates the two-person approach, however, is OSHA’s suggestion in Appendix C that the facilitator, in addition to being “fully knowledgeable in the proper implementation of the PHA methodology that is to be used,” must be “impartial in the evaluation.” It’s usually hard to claim that two people who both work in the process being evaluated are impartial.

Which brings us to a practical minimum of three people on the team: someone from operations, a process engineer, and the independent, impartial facilitator.

Who Else?

While it’s possible that a team consisting of three people will have all the experience and knowledge necessary to perform a satisfactory PHA, it is more likely that other experience and knowledge will be necessary. Not just useful, but necessary. The addition of other people to the team should be done with care, however. Too many people on the team, and the review will bog down. There is no requirement that every department in the plant be represented with a primary and alternate participant.

So, who else? It will depend on the nature of the process and the review. There may be some utility in having a scribe, but in the age of computers and PHA software, a scribe is not absolutely necessary when adequate worksheets are prepared before the review.

More likely will be the need for technical expertise. This might include a controls expert, an industrial hygienist, or a rotating equipment specialist. If there is likely to be a continuing need for their expertise, include them on the team. Otherwise, call them when the occasional question comes up that needs their input. That’s what cell phones are for, and most people would prefer to answer the occasional question than be tied up continuously in a PHA meeting to which they have little to contribute.

One department that is likely to be in continuous need throughout the review is the maintenance department. An experienced and knowledgeable maintenance mechanic can quickly bring clarity to questions about the process, especially during discussions of facility siting and human factors.

What About Plant Management?

People from plant management, like most people, already have duties that interfere with their ability to focus their undivided attention on a PHA, so will probably not be able to participate. If they choose to participate, however, they should participate with care. People in management positions did not get there by being timid, which means that during a PHA, they will have opinions and not be shy about expressing them. They may not be strong opinions, but they will be expressed strongly. This can have a stifling effect on others in the review. After all, who wants to contradict the boss?

When a senior manager from the plant joins a PHA review, they need to do it with discretion, taking care not to overpower the voices of others in the meeting or interfering  with the facilitator’s ability to manage the meeting.

The Ideal Size of a PHA Team

There is not a single ideal size of a PHA team. When using the Checklist methodology, the ideal size is three or four participants. For other PHA methodologies, the ideal size will range from four to seven. Any more than this and it becomes important to ask: Who doesn’t need to be here? Don’t forget that when specialized knowledge is needed to answer a specific question, cell phones work.

Don’t Be Afraid to Throw a Flag

If you find yourself in a PHA meeting where the participants don’t fit comfortably around the conference room table, don’t be afraid to play the role of referee and call “Too many players on the field.” Everyone wants the PHA to go as smoothly as possible, and many would welcome the opportunity to go back to their regular duties (which haven’t gone away just because they got pulled into a PHA). The call may not change who participates, but at least it will put everyone on notice that they have to be careful not to bog down the meeting.


  • Mike Schmidt

    With a career in the CPI that began in 1977 with Union Carbide, Mike was profoundly impacted by the 1984 tragedy in Bhopal and has been working on process safety ever since.