API TR 402-1995: Toxicology Report – Guidelines for Hearth Department Occupational Exposure Management

API Technical Report 402-1995, developed by the American Petroleum Institute, serves as a focused reference for toxicological risk assessment in hearth department operations within the petroleum refining and petrochemical industry. This report compiles data on hazardous substances commonly emitted or used in high-temperature processes such as coke calcining, steam reforming, and furnace heating. It provides recommended occupational exposure limits (OELs), health hazard profiles, and monitoring guidance to help facilities protect workers from acute and chronic health effects. Although published in 1995, its core principles continue to inform industrial hygiene programs, though users must verify limits against current regulations.

1. Scope and Applicability

API TR 402-1995 applies to petroleum refineries and petrochemical plants that operate hearth-type equipment, including:

• Coke ovens and fluid cokers
• Calcining furnaces
• Steam reformers and process heaters
• Thermal cracking and coking units

The report addresses the identification, evaluation, and control of chemical exposures during routine operations, maintenance, and upset conditions. It does not cover storage, transportation, or downstream distribution. Its scope is limited to airborne contaminants originating from combustion and thermal decomposition of hydrocarbon feedstocks, such as polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and inorganic gases like hydrogen sulfide.

2. Toxicological Requirements and Data

This section of the report presents toxicological profiles for key substances found in hearth environments. For each agent, the report documents physical and chemical properties, routes of entry, target organs, acute and chronic effects, reproductive toxicity, and carcinogenicity classifications. Based on the data, it recommends occupational exposure limits (OELs) as 8-hour time-weighted averages (TWAs) and short-term exposure limits (STELs).

The table above summarizes selected OELs as listed in API TR 402-1995. The report also emphasizes that these limits are intended to protect healthy adult workers from adverse effects over a working lifetime. They are not applicable to emergency exposures or susceptible populations.

Health Hazard Classification

API TR 402-1995 classifies substances into categories based on the severity of acute toxicity, carcinogenic potential, and target organ toxicity. For example, benzo(a)pyrene and coal tar pitch volatiles are classified as occupational carcinogens, requiring strict engineering controls and medical surveillance.

3. Implementation and Monitoring

Effective implementation of the guidelines in API TR 402-1995 requires a hierarchy of controls. The report recommends:

Engineering Controls

• Local exhaust ventilation with capture velocities of 100–150 ft/min for coke oven emissions.
• Process enclosures and sealed sampling ports.
• Use of substitute materials with lower toxicity where feasible.

Occupational Exposure Monitoring

• Personal and area air sampling using methods aligned with those cited in the report.
• Regular monitoring schedules based on exposure potential (e.g., quarterly for high-risk zones).
• Biological monitoring for benzene (urinary S-phenylmercapturic acid) when justified.

Personal Protective Equipment (PPE)

• Respiratory protection with assigned protection factors (APF) of at least 10–25 during maintenance or upset conditions.
• Protective clothing to prevent dermal absorption of PAHs and coal tar derivatives.

4. Compliance and Regulatory Integration

API TR 402-1995 is not a mandatory standard, but it provides authoritative guidance that can support compliance with various regulatory requirements:

• OSHA 29 CFR 1910.1002 – Coal tar pitch volatiles standard, which aligns with the report’s OEL of 0.2 mg/m³ (benzene-soluble fraction).
• OSHA 29 CFR 1910.1200 – Hazard Communication; the report’s data can be used to update Safety Data Sheets and training materials.
• EPA Regulations – The report can inform air emission inventories and risk assessments for facilities subject to MACT standards for coke ovens (40 CFR Part 63, Subpart L).

Because the document was published in 1995, facilities should integrate its recommendations with current practices from ACGIH (TLVs), OSHA (PELs), and NIOSH (RELs). Many of the OELs listed have been revised downward in the decades since the report was issued, reflecting advances in toxicology and risk assessment.

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