Carbon capture brings unusual cold to safety valves - and new testing standards to match

The physics of carbon dioxide under pressure creates a problem that oil and gas engineers have not had to deal with before. When high-pressure CO2 vents suddenly - the kind of worst-case scenario that safety valves are designed to manage - the rapid depressurization can produce temperatures cold enough to damage the very equipment meant to contain it.

This is a materially different challenge from conventional oil and gas production, where wellbore temperatures trend warm. Carbon capture and storage flips the thermal equation. And the safety valves that have been certified for decades of oil and gas service have not necessarily been tested for what CCS environments can throw at them.

Southwest Research Institute, based in San Antonio, completed facility upgrades in August 2024 to address exactly this gap. The changes allow the institute to test subsurface safety valves under the cold temperature conditions that CO2 releases can produce, contributing to a new body of standards that the industry is still building.

What makes CO2 cold

When a compressed gas expands rapidly, it cools - a principle described by the Joule-Thomson effect that most people have experienced when touching a pressurized aerosol can after use. For CO2, this cooling can be extreme. Under the pressure differentials involved in a CCS well failure or emergency closure, the temperature drop during a valve slam event can reach conditions that would freeze moisture, embrittle certain materials, and alter the mechanical properties of components in ways that room-temperature certification testing would not predict.

Research Engineer Nicole Lemon at SwRI noted that CCS applications present unique challenges for these valves because of the extremely cold temperatures. The challenge is not just achieving those temperatures in a laboratory setting - it is achieving them reliably and consistently enough to run meaningful certification tests.

Liquid nitrogen and a plug-and-play design

The SwRI solution uses liquid nitrogen delivered through ducting to cool the test environment to the required extreme temperatures. The system was designed to avoid icing complications that could interfere with test conditions or damage equipment - a practical problem when you are deliberately creating the conditions for ice formation in a controlled setting.

The facility also incorporated ergonomic improvements and a plug-and-play lid design that reduces the labor required to configure the test setup between runs. In testing facilities where each configuration might need to be repeated across multiple valve specifications, reducing setup time has a meaningful effect on throughput and operational cost. Safer working conditions for technicians handling cryogenic equipment were an additional driver.

Together, these changes allow the facility to support CCS valve certification alongside its existing oil and gas testing services without requiring a complete rebuild of existing infrastructure.

New standards for a new industry

SwRI contributed to the development of API 14A, 13th Edition Addendum 1, released in December 2025. The American Petroleum Institute's 14A standard governs subsurface safety valves used in oil and gas production; the addendum extends its scope to CCS applications, including the cold temperature testing requirements that SwRI's facility upgrade was designed to support.

This is how industrial safety standards typically develop: a new application creates conditions that existing standards do not cover, test facilities develop the capability to evaluate performance under those conditions, and standards bodies incorporate the resulting data into updated specifications. The timeline from CCS application identification to published standard addendum in this case spans several years of parallel technical development.

The facility is also pursuing cooled gas slam testing - replicating the rapid valve closure event under cold CO2 conditions that represents the worst-case CCS scenario. This test type is more technically demanding than static cold temperature exposure, as it requires coordinating the thermal and dynamic aspects of the event simultaneously.

Safety valves in the CCS infrastructure picture

Subsurface safety valves sit deep in the wellbore, typically hundreds to thousands of feet below the surface, and function as the last line of automated defense against an uncontrolled release from the reservoir. In conventional oil and gas wells, they have a multi-decade track record. CCS introduces CO2 as the working fluid at pressures and flow rates that can generate the cold temperature conditions described above - conditions that could affect valve materials, seals, and actuation mechanisms in ways the existing certification record does not cover.

As carbon capture projects scale from pilot installations to the commercial-scale operations that climate targets would require, the certification infrastructure for the equipment involved needs to scale with them. SwRI's facility upgrade is a piece of that infrastructure, and the API addendum provides the regulatory framework that makes the testing meaningful to project developers and insurers alike.