40 CFR 63 Subpart JJJJJJ: EPA Area Source Boilers (6J)

Regulatory citation: 40 CFR Part 63, Subpart JJJJJJ, National Emission Standards for Hazardous Air Pollutants for Industrial, Commercial, and Institutional Boilers Area Sources

What Is the 6J Boiler Rule?

Subpart JJJJJJ, known as the 6J rule, applies to industrial, commercial and institutional boilers located at area sources of hazardous air pollutants. In practice it covers boilers that burn coal, biomass or oil. Gas-fired boilers are excluded.

Most covered boilers must have periodic tune-ups. Larger existing boilers needed a one-time energy assessment, and some larger units also have numeric emission limits.

Why the 6J Rule Matters

Boilers burning solid and liquid fuels release mercury, particulate matter, carbon monoxide and other pollutants. Regular tune-ups help keep combustion efficient and emissions low.

Core Requirements

1. Determine Whether Your Boiler Is Covered (63.11193–63.11195)

Excluded units include gas-fired boilers, hot water heaters, residential boilers, temporary boilers, electric boilers and boilers covered by another air toxics standard. A gas-fired boiler can burn liquid fuel only during gas curtailment, gas supply interruption, startups or periodic testing, and testing, maintenance and training on liquid fuel may not exceed a combined 48 hours per calendar year.

2. Know Whether the Boiler Is New or Existing (63.11194)

A boiler is existing if construction or reconstruction began on or before June 4, 2010, and new if it began after that date. Existing boilers had to meet their tune-up, emission limit and energy assessment requirements by March 21, 2014.

3. Perform Tune-Ups on Schedule (63.11223 and Table 2)

Coal-fired boilers under 10 MMBtu/hr, biomass-fired boilers and oil-fired boilers over 5 MMBtu/hr need a tune-up every two years, no more than 25 months apart. A tune-up every five years, no more than 61 months apart, applies to seasonal boilers, limited-use boilers, oil-fired boilers of 5 MMBtu/hr or less and boilers with an oxygen trim system.

4. Follow the Tune-Up Procedure (63.11223(b))

Each tune-up must include inspecting the burner, the flame pattern and the air-to-fuel ratio controls, and optimizing carbon monoxide emissions. Carbon monoxide in ppm and oxygen in volume percent must be measured before and after adjustments. The results must be kept in an on-site report. If the boiler is not running on the due date, the tune-up must be done within 30 days of startup.

5. Complete the One-Time Energy Assessment (Table 2)

Existing coal, biomass or oil-fired boilers of 10 MMBtu/hr or more, other than limited-use boilers, needed a one-time energy assessment by a qualified energy assessor. The assessment covers a visual inspection, operating characteristics, an inventory of major energy-using systems, a list of energy conservation measures and their savings potential, and a report on costs and payback.

6. Meet Emission Limits Where They Apply (63.11201 and Table 1)

Table 1 sets numeric emission limits for existing coal-fired boilers of 10 MMBtu/hr or more, for mercury and carbon monoxide. New coal-fired boilers of 10 MMBtu/hr or more have particulate matter, mercury and carbon monoxide limits, and new biomass and oil-fired boilers of 10 MMBtu/hr or more have particulate matter limits unless they are seasonal or limited-use boilers.

7. Notify, Certify and Keep Records (63.11225)

An initial notification and a notification of compliance status are required. A compliance certification report must be prepared by March 1 each year, or every two or five years for boilers subject only to tune-ups and the energy assessment, and submitted on request. If there were any deviations, the report must be submitted by March 15. Records of tune-ups, energy assessments and fuel use must be kept for 5 years, with at least 2 years on site or readily accessible.

Common Compliance Approaches

Schedule Tune-Ups With the Boiler Contractor

Add the 25-month or 61-month deadline to the service contract and require a written report with before and after CO and oxygen readings.

Keep One File per Boiler

Store the boiler's subcategory, rated heat input, tune-up reports, energy assessment and compliance certifications together.

Track Liquid Fuel Hours on Gas Boilers

Log testing hours on backup oil so a gas-fired boiler stays within the 48-hour limit and keeps its exclusion.

Example: 6J Compliance in Practice

A school district operates two existing 6 MMBtu/hr oil-fired boilers. Every two years, a contractor inspects the burners and flame pattern, adjusts the air-to-fuel ratio and records carbon monoxide and oxygen readings before and after. The facilities manager files the tune-up reports and signs a compliance certification report. A new gas-fired boiler at another school is not covered, so the district logs its rare oil test runs to stay under 48 hours a year.

Related regulations: EPA Title V Operating Permits, EPA Greenhouse Gas Reporting Program, EPA RICE NESHAP (Subpart ZZZZ).

Note: This summary reflects federal EPA requirements. Many state and local air agencies have delegated authority for these rules and may add their own permit conditions or stricter limits. Always check the current regulation text and any state or local rules that apply to you.

Frequently Asked Questions

Are natural gas boilers covered by the 6J rule?

No. Gas-fired boilers are excluded under 63.11195(e), provided liquid fuel use is limited to the situations in the definition, including no more than 48 hours per calendar year of testing, maintenance and training.

How often is a boiler tune-up required?

Most covered boilers need a tune-up every two years, no more than 25 months apart. Seasonal, limited-use, small oil-fired and oxygen trim boilers need one every five years, no more than 61 months apart.

How long must 6J records be kept?

Five years after each recorded action, with at least the first two years on site or readily accessible from a central location.