On August 12, 2020, the United States Environmental Protection Agency (US EPA) finalized amendments to the Miscellaneous Organic NESHAP (MON) as part of the residual risk and technology review (RTR) process. While compliance dates for several changes in the MON RTR have passed, the compliance date for the majority of the changes is coming soon – August 12, 2023. One of these changes made in the MON RTR was associated with closed vent systems.
What is a Closed Vent System (CVS)?
A closed vent system (CVS) is defined as a system that is not open to the atmosphere and that is composed of hard-piping, ductwork, and connections that transport gas or vapor from a piece or pieces of equipment to a control device or back into a process. The MON prescribes work practice standards for CVS utilized to manage Group 1 emission sources and MON regulated pressure relief devices (PRDs).
Existing CVS Requirements in the MON
MON regulated CVS must be initially inspected per Method 21 and inspected visually annually thereafter. Additionally, bypasses to the atmosphere contained within CVS:
- Must be identified;
- Must have either:
- DCS notification of and historian records of either:
- Valve position, or
- Flow indication (switch or flowmeter); or
- Manual points of bypass must be:
- Secured in the non-diverting position utilizing either a car-seal or lock-and-key configuration, with associated car-seal or lock-and-key logs of valve position change, and
- Inspected physically on a monthly basis to confirm security and correct position in the field.
What CVS Requirements Changed in the MON RTR?
The MON RTR did not change the “footprint” of a given CVS, as Group 1 emissions sources and PRDs have always been included, however US EPA did remove exemptions for certain points of bypass. Historically, high point bleeds, low point drains and PRDs within a CVS have been exempt from the bypass tracking, security, and recordkeeping requirements listed above. However, with the updates to the MON RTR, these exemptions are being removed from regulation, effective August 12, 2023.
As such, all bypasses, automatic, manual, traditionally exempt high-point bleeds, low point drains and PRDs, must comply with the MON bypass requirements.
For open-ended valves, US EPA has provided a compliance option to manage these bypasses in accordance with the standard for open-ended valves in Subparts H or UU, ensuring these components are equipped with a second valve, plug, flange, or cap in lieu of a manual lock or car-seal configuration. While monthly inspections for this compliance option are not prescribed, Trinity recommends a periodic internal inspection of such components (monthly, quarterly, or at a minimum annually as part of the CVS inspection) to ensure compliance.
A wave of CVS enforcement is expected post MON compliance date to confirm compliance with this revised standard. Now is a good time to review your CVS monitoring and recordkeeping programs to ensure that each CVS is properly identified and inspected and to ensure all bypasses, both historic and newly regulated, are either equipped with DCS/DHS records of bypass or manually secured in the field and, as appropriate, inspected monthly.
Trinity’s Chemical Sector Services (CSS) Group is well versed in helping chemical and refining industry personnel navigate their way through implementation of these changes. If you need any assistance reviewing your CVS, identifying all potential bypasses, or updating your CVS compliance program, please feel free to reach out to Kim Teofilak.
