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IFRs and EFRs - NSPS or NESHAPs, That is the Question

On January 19th, the U.S. EPA finalized amendments to 40 CFR Part 60, Subpart K(b) – 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, (Including Petroleum Liquid Storage Vessels) for Which Construction, Reconstruction, or Modification Commenced After July 23, 1984,). Specifically, the new rule allows owners or operators of internal floating roof tanks (IFRs) or external floating roof tanks (EFRs) subject to 40 CFR Part 60, Subpart K(b) (NSPS K(b) to alternatively comply with the requirements in the National Emission Standards for Storage Vessels (Tanks) – Control Level 2 found at 40 CFR Part 63 Subpart WW (NESHAP WW) as an alternative standard, subject to certain caveats and exceptions for monitoring, record-keeping, and reporting.

As a refresher, to reduce volatile organic compound (VOC) emissions from aboveground storage tanks, NSPS K(b) requires the use of either an EFR, an IFR, or a closed vent system and a control device. NSPS K(b) also specifies testing, monitoring, record-keeping, reporting, and other requirements to ensure compliance with the standards. More specifically, 40 CFR 60.113b requires that certain inspections for IFR and EFR occur at least once within certain defined timeframes (such as at least once every year, 5 years, or 10 years). The NSPS K(b) standard requires that a rim seal be installed to prevent VOC emissions through gaps between the floating roof and the inner wall of the storage tank. NSPS K(b) also requires deck fittings on the floating roof to be equipped with a gasket cover or lid that is kept in the closed position except when the device is in actual use. NSPS K(b) requires owners or operators to conduct visual inspections to check for defects in the floating roof, rim seals and deck fittings that could expose the liquid surface to the atmosphere and potentially result in VOC emission losses.

Since promulgation of Subpart K(b), the EPA promulgated 40 CFR Part 63, Subpart WW, which is applicable to storage vessels containing organic materials, as part of the generic maximum achievable control technology (MACT) standards program. Like the NSPS K(b) standards for floating roof tanks, NESHAP WW is a combination of design, equipment, work practice, and operational standards. Both rules specify monitoring, record-keeping, and reporting requirements for EFRs and IFRs, and both include numerous requirements for inspections. The inspections required by NESHAP WW are intended to achieve the same goals as those inspections required by NSPS K(b). For storage vessels equipped with a floating roof, if there is visual access, NESHAP WW allows that the visual inspection of the floating roof deck, deck fittings, and rim seals be conducted while the tank remains in service, from the top-side of the floating roof. This is referred to as an in-service top-side visual inspection. Explained in another way, in the case of an IFR, if an owner or operator has physical access to the inside of the tank above the floating roof and a floating roof design that allows inspectors visual access to all rim seals and deck fittings of the floating roof while the storage vessel is in service, then NESHAP WW does not require the owner or operator to take the storage vessel out of service for these inspections thereby avoiding the need to empty and degas the vessel for the sole purpose of conducting the inspection. This contrasts with NSPS K(b) which requires that these inspections be conducted when the storage vessel is out-of-service.

Owners or operators that choose to use this alternative must continue to comply with the Subpart K(b) monitoring requirements. This alternative standard would be available for each storage tank. In other words, an owner or operator with IFRs or EFRs can choose to use (or not use) the alternative for each storage tank.

CFR Environmental has a long track record of providing support to storage tank operators through the air emissions and associated permitting for over 30 years. Contact us to determine how this update affects your terminal.


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