Episode 44 - Common Process Safety Management Chemicals

Episode 44 introduces the chemicals most frequently covered under OSHA’s Process Safety Management (PSM) Standard (29 CFR 1910.119). Dr. Ayers explains why certain chemicals are regulated, what makes them hazardous, and how their properties influence process safety requirements.

The core message: PSM chemicals are dangerous because of their potential for catastrophic consequences — fire, explosion, or toxic release. Understanding their hazards is the first step in controlling them.

  🧭 Why Certain Chemicals Are Covered by PSM

OSHA regulates chemicals under PSM because they have one or more of the following characteristics:

• Highly toxic

• Highly reactive

• Highly flammable

• Capable of rapid energy release

• Able to form explosive mixtures

• Dangerous even in small quantities

These chemicals can cause mass casualties, major property damage, and community‑scale impacts if released.

  🧪 Common Categories of PSM Chemicals

Episode 44 groups the most common PSM chemicals into several hazard categories.

  1. Highly Toxic Chemicals

These chemicals can cause severe injury or death at low concentrations.

Examples include:

• Chlorine

• Phosgene

• Hydrogen sulfide (H₂S)

• Anhydrous ammonia

Hazards include respiratory failure, pulmonary edema, and rapid incapacitation.

  2. Flammable Liquids and Gases

These chemicals can ignite or explode when mixed with air.

Examples include:

• Propane

• Butane

• Ethylene

• Hydrogen

• Acetylene

Flammables are the most common PSM‑covered chemicals because they are widely used in industry.

  3. Reactive Chemicals

These chemicals can undergo violent reactions if mixed, heated, or contaminated.

Examples include:

• Peroxides

• Organic nitrates

• Polymerizable monomers

• Water‑reactive metals

Reactivity hazards often lead to runaway reactions and vessel overpressure.

  4. Explosive or Energetic Chemicals

These chemicals can release large amounts of energy rapidly.

Examples include:

• Hydrogen peroxide (high concentration)

• Ammonium nitrate

• Certain oxidizers

These materials require strict control of temperature, contamination, and confinement.

  5. Corrosive Chemicals

While not always acutely toxic, corrosives can damage equipment and lead to secondary failures.

Examples include:

• Sulfuric acid

• Hydrochloric acid

• Sodium hydroxide

Corrosion is a major contributor to mechanical integrity failures.

  🔍 Why These Chemicals Matter in PSM

Dr. Ayers emphasizes that PSM chemicals are dangerous not just because of their inherent hazards, but because of:

• Quantity stored

• Process conditions (pressure, temperature)

• Potential for rapid release

• Proximity to workers and communities

A small amount of a highly toxic chemical can be just as dangerous as a large amount of a flammable one.

  🧪 Common Incident Themes Highlighted in the Episode

Many catastrophic events involving PSM chemicals share similar causes:

• Loss of containment

• Overpressure events

• Runaway reactions

• Improper mixing

• Equipment failure

• Human error during startup or shutdown

• Inadequate hazard communication

Understanding the chemicals helps prevent these failures.

  🔗 How Chemical Hazards Connect to Other PSM Elements

Chemical properties directly influence:

• PSI — hazard data must be accurate

• PHA — scenarios depend on chemical behavior

• Operating Procedures — limits and steps reflect chemical hazards

• Training — workers must understand chemical risks

• Mechanical Integrity — materials of construction depend on corrosivity and reactivity

• Emergency Planning — response depends on toxicity and flammability

Chemical knowledge is the foundation of process safety.

  🧑‍🏫 Leadership Responsibilities

Safety leaders must:

• Ensure chemical hazard information is complete and current

• Train employees on the specific hazards of PSM chemicals

• Verify that safeguards match the chemical risks

• Integrate chemical properties into PHAs, procedures, and MI programs

• Communicate hazards clearly to contractors and responders

The episode’s core message: You cannot manage process safety if you don’t understand the chemicals.