EPA Offers Flexibility with Alternative Storage Tank Inspection Method
Refinery tank farm

On January 19, 2021, the United States Environmental Protection Agency (EPA) published a final rule amending the “1987 Standards of Performance for Volatile Organic Liquid Storage Vessels (Including Petroleum Liquid Storage Vessels) for which Construction, Reconstruction, or Modification Commenced after July 23, 1984” (Part 60, NSPS subpart Kb). The amended “NSPS Kb” rule allows tank owners and operators an option to perform inspections without emptying and degassing storage tanks.

A little background on NSPS Kb

NSPS Kb includes inspection requirements for storage vessels equipped with either an external floating roof (EFR) or an internal floating roof (IFR). In certain circumstances, the standards require the owner or operator to empty and degas the tank so that a “close-up” inspection can be conducted from inside the tank (required at least once every 10 years). This inspection requires the tank to be taken out of service and degassed so an inspector can enter the tank and conduct visual inspections for holes, tears, or other openings in the tank rim or fitting seals. Emptying and degassing events are undesirable primarily because owners or operators must take the storage vessel completely out-of-service, resulting in scheduling concerns and the need for spare storage capacity. Excess air emissions are also created during these inspection events.

This final action allows owners or operators of EFR and IFR storage vessels subject to the 1987 NSPS Subpart Kb rule the flexibility to instead comply with the requirements specified in the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Storage Vessels (Tanks)—Control Level 2 (Part 63, Subpart WW. The NESHAP Subpart WW requirements allow for less cumbersome “in-service” visual inspections that may occur without emptying and degassing the storage tank, with certain caveats and exceptions for monitoring, recordkeeping, and reporting.  

If your team is considering shifting its tank inspection approach, Trihydro’s air compliance team can help evaluate applicable regulatory requirements and implement compliance programs for storage vessels using the latest electronic data collection, data transfer, recordkeeping, and report generation tools.  

Readers should note: This rule is included in the list of climate-related agency actions that the new Biden Administration has directed the heads of relevant agencies to review.

Operators should also carefully consider and manage the potential additional safety risk posed to inspectors when performing in-service inspections, as this inspection will likely be a confined space entry for accessing both IFR and EFR roof decks.   

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John Pfeffer
Senior Air Professional

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