PT Notes
CSB Recommendations on Reactive Hazards to EPA and OSHA
PT Notes is a series of topical technical notes on process safety provided periodically by Primatech for your benefit. Please feel free to provide feedback.
The U.S. Chemical Safety and Hazard Investigation Board (CSB) has previously called on the U.S. Occupational Safety and Health Administration (OSHA) and the U.S. Environmental Protection Agency (EPA) to address gaps in regulating reactive chemical hazards. The CSB is once again calling on EPA and OSHA to “close a glaring gap in their chemical regulations and provide much-needed additional coverage of reactive chemicals”. The CSB believes that OSHA's and EPA's current regulations do not adequately protect against hazards presented by reactive chemicals.
This latest call for action on reactive chemical hazards resulted from the CSB’s investigation into the December, 2020 fatal incident at Optima Belle LLC facility in Belle, WV. The incident occurred during Optima’s production of a sanitizing compound. Water was being removed from the compound in a dryer when the compound underwent a runaway decomposition reaction that over-pressurized the dryer causing it to explode and release toxic chlorine gas. One employee was killed. Metal debris and dryer fragments were propelled off-site and within the facility, striking a methanol pipe that then caught fire, leading to an estimated $33 million in property damage. Also, a shelter-in-place order was issued for the neighboring community. Optima’s drying process was not subject to regulation by either the OSHA Process Safety Management (PSM) standard or the EPA Risk Management Program (RMP) rule and Optima did not have a process safety management program.
The CSB noted that OSHA and EPA currently use predefined chemical lists to identify the processes subject to coverage under the PSM standard and RMP rule and that OSHA and EPA did not adequately consider reactive chemical hazards when developing their chemical lists, and, as a result, many reactive chemicals, including the chemical involved in the Optima incident, are not covered by the regulations. The CSB also noted that this regulatory coverage gap points to a weakness with relying on fixed chemical lists to determine regulatory coverage and the CSB believes this gap contributed to the Optima incident and many other reactive chemical incidents over the years.
The CSB reiterated its recommendation to EPA from 2001:
Revise the Accidental Release Prevention Requirements, 40 CFR 68, to explicitly cover catastrophic reactive hazards that have the potential to seriously impact the public, including those resulting from self-reactive chemicals and combinations of chemicals and process-specific conditions.
The CSB has replaced its recommendations to OSHA from 2001 with an updated version:
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Update OSHA’s Chemical Reactivity Hazards website to include newer reactivity assessment tools.
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Ensure that the chemical industry is aware of the Chemical Reactivity Hazards website (https://www.osha.gov/chemical-reactivity) by developing and implementing a comprehensive outreach plan that actively targets the chemical industry and related trade associations.
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Amend the PSM Standard, 29 CFR 1910.119, to achieve more comprehensive control of reactive hazards that could have catastrophic consequences.
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Broaden the application to cover reactive hazards resulting from process-specific conditions and combinations of chemicals. Additionally, broaden coverage of hazards from self-reactive chemicals. In expanding PSM coverage, use objective criteria. Consider criteria such as the North American Industry Classification System (NAICS), a reactive hazard classification system (e.g., based on heat of reaction or hazardous gas evolution), incident history, or catastrophic potential.
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In the compilation of process safety information, require that multiple sources of information be sufficiently consulted to understand and control potential reactive hazards. Useful sources include but are not limited to:
Literature surveys (e.g., Bretherick’s Handbook of Reactive Chemical Hazards, Sax’s Dangerous Properties of Industrial Materials, CAS SciFinder).
Information developed from computerized tools (e.g., ASTM’s CHETAH, CCPS’s Chemical Reactivity Worksheet).
Chemical property data compiled in PubChem and the REACH (Registration, Evaluation, and Authorization of Chemicals) dossiers maintained by the European Chemicals Agency (ECHA).
Chemical reactivity test data produced by employers or obtained from other sources following established standards such as:
ASTM E537-20, Standard Test Method for Chemicals by Differential Scanning Calorimetry;
ASTM E1981-22, Standard Guide for Assessing Thermal Stability of Materials by Methods of Accelerating Rate Calorimetry;
ASTM E2550-21, Standard Test Method for Thermal Stability by Thermogravity; and
ASTM E1231-19, Standard Practice for Calculation of Hazard Potential Figures of Merit for Thermally Unstable Materials.
Relevant incident data from the plant, the corporation, industry, and government.
- Augment the process hazard analysis (PHA) element to explicitly require an evaluation of reactive hazards. In revising this element, evaluate the need to consider relevant factors, such as:
Rate and quantity of heat or gas generated.
Maximum operating temperature to avoid a runaway reaction from decomposition.
Time to Maximum Rate under Adiabatic Conditions (TMRad).
Thermal stability of reactants, reaction mixtures, byproducts, waste streams, and products.
Effect of variables such as charging rates, catalyst addition, and possible contaminants.
Understanding the consequences of runaway reactions or hazardous gas evolution.
Arguably, the two most important aspects of these recommendations are the need for companies to be aware of and understand reactive chemical hazards that may be present in their processes and be able to address them in their PHA studies. The CSB has thoroughly documented sources of information on reactive chemical hazards. Of course, companies must be motivated to screen their processes for reactive chemical hazards. Details on how to address reactive chemical hazards in PHA can be found in these articles:
Consider Chemical Reactivity in Process Hazard Analysis, P. Baybutt, Chemical Engineering Progress, Vol. 111 (1), pages 25 - 31, January 2015.
Chemical reactivity and hazard and operability (HAZOP) studies, P. Baybutt, Loss Prevention Bulletin, Issue 244, August, 2015.
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