“You keep using that word. I do not think it means what you think it means.” — Mandy Patinkin as Inigo Montoya from The Princess Bride (1987)
I, like many older Americans, worry about my blood pressure enough to check it regularly. And like most people who check their blood pressure regularly, I know what the numbers mean. The top number, the systolic pressure, is the pressure in mm Hg when the heart beats. The bottom number, the diastolic pressure, is the pressure in mm Hg when the heart is at rest between beats.
A systolic pressure over 130 mm Hg or a diastolic pressure over 80 mm Hg is considered high blood pressure, a symptom of hypertension. A systolic pressure over 120 mm Hg but a diastolic pressure less than 80 mm Hg is considered elevated blood pressure. It is only when blood pressure is less than 120/80 that it is considered normal.
Yet the Centers for Disease Control report that 48.1% of American adults have high blood pressure (> 130 mm Hg systolic pressure or > 80 mm Hg diastolic pressure). When we included people with elevated blood pressure in that percentage, it means that well less than half of American adults have blood pressure less than 120/80, what medical professionals call “normal.” Since when is a condition shared by less than half of the population considered the norm for that population?
I readily concede that keeping blood pressure below 120/80 is healthier, and it is something I strive to do. But normal? I, like Inigo Montoya, do not think it means what you think it means.
“Normal” in Process Safety
A brilliant explanation of “normal” comes from the National Fire Protection Association (NFPA) committee that wrote NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas – 2024 Edition. In §6.3.3, it says, “The term normal does not necessarily mean the situation that prevails when everything is working properly.”
The committee that wrote NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas – 2024 Edition took it further. In §5.3.1.2, they stress, “Normal does not necessarily mean the situation that prevails when everything is working properly. For instance, there could be cases in which frequent maintenance and repair are necessary. These are viewed as normal and, if quantities of a flammable liquid or a combustible material are released as a result of maintenance, the location is Division 1.”
“Normal” and Management of Change
I work with a facility that relies on nitrogen to keep a hazardous process purged and inert. They have a low-pressure interlock on each piece of rotating equipment that stops the equipment and closes the feed valves, to protect against the loss of nitrogen. When they perform maintenance on the equipment, which requires opening up the equipment, they shut off the nitrogen so as not to expose the maintenance mechanics to an asphyxiation hazard. At the conclusion of the work, before pressurizing the equipment, they test the rotation of the equipment. To do that, though, they have to bypass the low nitrogen pressure interlock. This bypass step is a normal part of maintenance.
Every time they do it, however, they go through their management of change procedure.
For a normal maintenance practice.
Does OSHA’s PSM Standard require this? Must they complete the paperwork for an MOC whenever they perform maintenance on their nitrogen-inerted equipment? The regulation requires employers to manage changes to procedures, among other things, but they are not changing procedures. They are simply implementing an existing practice; in other words, a written procedure prepared in compliance with the mechanical integrity requirements of the PSM standard.
Can they apply their MOC procedure? Sure. But every unnecessary effort in the name of safety diverts from the finite resources available to do what is truly needed for safety.
When “Normal” Is Not What We Want
“Normal” does not necessarily mean “working properly”, or in the case of blood pressure, “healthy.” It means a situation or condition that we can and should expect. When a situation is normal, it is not a change. Maggie Stiefvater once said, “I didn’t want normal until I didn’t have it anymore.” It is important for us to understand what is normal and act accordingly. If we don’t like the situation or condition as it is, then we need to change the situation or condition, not our definition of “normal.”
As for my blood pressure? It fluctuates. Sometimes it’s healthy, sometimes it’s elevated. Occasionally, it’s high. I’m working on it.
