New Source Performance Standards (NSPS) — 40 CFR Part 60

The NSPS program applies prospectively — it covers sources that commence construction, reconstruction, or modification after the applicability date of the relevant subpart. Existing sources predating the subpart are not subject to it, though they may be subject to parallel requirements under NESHAP or state regulations.

NSPS structure

Part 60 is organized into subparts, each identified by a letter code. The most LDAR-relevant subparts for the industrial process sector:

• SOCMI equipment leaks (Synthetic Organic Chemicals Manufacturing Industry):
  • Subpart VV — facilities constructed, reconstructed, or modified January 5, 1981 through November 7, 2006.
  • Subpart VVa — facilities constructed, reconstructed, or modified after November 7, 2006 (most current sources).
  • Subpart VVb — promulgated May 2024 final rule; applies to sources commencing construction after the 2023 proposal date.
• Petroleum refinery equipment leaks:
  • Subpart GGG — refineries constructed, reconstructed, or modified January 4, 1983 through November 7, 2006.
  • Subpart GGGa — refineries constructed, reconstructed, or modified after November 7, 2006. Subpart GGGa references the requirements of Subpart VVa except for connector monitoring.
• Oil and gas sector (methane-focused):
  • Subpart OOOOb — final rule 2024; applies to sources constructed, modified, or reconstructed after December 6, 2022. Includes Method 21 alternative LDAR program at §60.5401b for onshore natural gas processing plants.
  • Subpart OOOOc — EPA emission guidelines for existing oil and gas sources, implemented through state plans.

Key requirements under SOCMI and refinery equipment leak subparts

Under Subpart VVa (the dominant current SOCMI equipment leak rule), covered facilities must:

• Establish a monitoring program for valves, pumps, compressors, pressure relief devices, open-ended lines, sampling connections, and (under VVa) connectors.
• Conduct monitoring at frequencies specified by component type and service classification.
• Apply the applicable leak definition threshold (500 ppmv for valves in gas service under VVa).
• Repair detected leaks within the specified timeframe.
• Maintain recordkeeping and submit semiannual reports.

Subpart GGGa applies these same requirements to petroleum refineries with minor variations.

Enforcement

NSPS violations are enforceable under Clean Air Act Section 113. Civil penalties are adjusted annually for inflation under 40 CFR 19.4. EPA's Civil Penalty Policy and source-category-specific guidance address penalty determination in enforcement settlements.

The role of P&IDs

NSPS compliance depends on a complete component inventory. The source record for that inventory — which components exist in the facility, what service they are in, what monitoring frequency applies — is the governing P&ID. Every facility subject to an equipment leak NSPS needs its P&IDs to match the field installation, and needs to be able to demonstrate that alignment under audit.