Navigating Regulatory Changes in the Tank Industry
Regulatory updates can present challenges for any industry, particularly one as heavily regulated as aboveground storage tanks. However, the latest updates to EPA standards are designed with clear objectives: reducing emissions from storage tank operations.
Overview of NSPS and Subpart Kc
The latest changes fall under the New Source Performance Standard (NSPS) for Volatile Organic Liquid (VOL) Storage Vessels. Established in 1987, NSPS Subpart Kb has long governed storage tank construction, reconstruction, and modification within the petrochemical sector. This regulation set standards for vapor pressure thresholds, inspection procedures, reporting requirements, and control equipment for both internal and external floating roof tanks.
The recent updates in Subpart Kc aim to further reduce emissions—an estimated 1,085 tons annually—and improve operational safety. Whether that value is true or not, understanding these changes is crucial for ensuring compliance and optimizing storage tank management.
Applicability of Subpart Kc
The new regulations apply in the following scenarios:
- Construction of a new storage tank
- Reconstruction of a tank when costs exceed 50% of new construction
- Modification of an existing tank to store a product with a higher true vapor pressure (TVP)
These changes affect tanks built, modified, or reconstructed on or after October 4, 2023. Existing tanks that do not meet these criteria remain subject to Subpart Kb requirements. However, proactively aligning operations with Subpart Kc can enhance compliance across all relevant industry regulations, including 40 CFR Part 60, Subpart WW, and improve workplace safety by reducing exposure to hazardous air pollutants.
Key Changes Under Subpart Kc
The updated standards focus on two primary areas:
- Stricter emission controls on volatile organic compounds (VOCs)
- Enhanced monitoring and reporting requirements
The table below highlights the regulatory shifts in VOC emissions limits:
|
Requirement |
Subpart Kb |
Subpart Kc |
|
Vessel Capacity |
20,000 – 40,000 gallons (≤75 m3 to >151 m3) |
Same |
|
Chemical Applicability |
Heptane, Ethyl Alcohol, Benzene, Hexane, Gasoline |
+Benzene, +Hexane, +Toluene |
|
TVP ≥20,000 gal & <40,000 gal |
≥4 psia |
≥1.5 psia |
|
TVP ≥40,000 gal |
≥0.75 psia |
≥0.5 psia |
|
VOC Control Efficiency (Degassing) |
95% |
98% until reaching 10% Lower Explosive Limit (LEL) |
Highlights of Compliance Requirements by Tank Type
External Floating Roof Tanks (EFRs)
- Elimination of slit fabric for deck fitting gaps
- Welded deck seams required
- Slotted guidepoles must include a liquid-mounted primary seal
- Access hatches and float well covers must be gasketed and bolted at all times
- Rim-mounted secondary seal required with annual inspections
- Primary seal inspections every five years
- Low-level alarm system mandatory for monitoring landing events
Internal Floating Roof Tanks (IFRs)
- Vapor-mounted primary seals no longer permitted; liquid-mounted seals required
- Annual inspections of shoe seals and deck fittings; defects must be repaired within 45 days
- Rim-mounted secondary seal and low-level alarm system required
- Annual LEL monitoring over a 20-minute rolling average, under specific wind conditions
- Failure threshold: LEL must remain below 25%; corrective actions required within 30 days
- Double-seal systems now move from a 5-year to a 10-year inspection cycle
Closed Vent Systems
- Implementation of pressure relief devices and bypass lines to prevent emissions
- Continuous Monitoring System (CMS) required for control devices
- Quarterly visible, audible, and olfactory inspections
- Annual leak detection using Method 21 with VOC detector instruments
- Leaks must be repaired within 5 days and confirmed within 15 days
Reporting Requirements Under Subpart Kc
A significant change under Subpart Kc is the shift from event-based reporting to comprehensive documentation. Unlike Subpart Kb, which required reporting only for failures and repairs, Subpart Kc mandates reporting for all inspections, regardless of outcome. Required reports include:
- Seal inspections
- LEL readings
- Roof landings
These reports must be submitted semi-annually using the EPA’s electronic reporting tool.
Ensuring Compliance with Subpart Kc
HMT is committed to assisting companies in navigating these regulatory changes. Our industry-leading solutions include:
- Compliant tank seals and fittings to meet Kc standards
- Inspection and monitoring services to streamline compliance
- Educational resources to help facility operators stay ahead of evolving regulations
For expert consultation on achieving compliance, contact HMT today.
