Praxair - Norcross, GA - Executive Summary |
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The Praxair facility at Norcross, Georgia is a hydrogen production plant. We react steam and methane (natural gas) to form hydrogen gas, which we then purify and distribute through a pipeline to a nearby customer. In addition to the hydrogen that we produce on-site, we also have four cryogenic liquid hydrogen storage vessels that are connected to the pipeline, which supplement the hydrogen supply to our customer. Hydrogen is listed as a regulated flammable substance in EPA's Risk Management Program rule, with a threshold quantity of 10,000 pounds. The production and storage process at the Norcross plant contains about 80,000 pounds of hydrogen, and is therefore subject to the RMP rule. Under the RMP rule, Praxair is required to report a Worst Case Scenario for the Norcross plant, which is defined by the EPA as the release of the entire contents of the largest hydrogen vessel in our process, with essentially none of the safety systems and devices that are in place to prevent such a n occurrence functioning as designed. The release is assumed to ignite, causing a vapor cloud explosion. Given these conditions, we are then required to estimate the distance to an EPA-specified flammable endpoint, which is defined to be an overpressurization effect of 1 pound per square inch. At the Norcross facility, the largest hydrogen vessel contains about 22,400 pounds. Using the criteria listed above, the Worst Case Scenario would result in a maximum impact distance of about 0.32 miles to the EPA-specified endpoint. To determine this distance, we used the Compressed Gas Association's "Risk Management Plan Guidance Document for Bulk Liquid Hydrogen Systems." We are also required to report an Alternative Release Scenario, or planning scenario, under the RMP rule. While an Alternative Release may never occur at a facility, it is generally accepted to be more likely, or more credible, than the Worst Case Scenario, and can be used by the facility and local response organizatio ns to plan community emergency response activities. The RMP rule assumes more typical atmospheric and weather conditions for an Alternative Release Scenario, and allows a facility to take credit for safety devices and other mitigation systems that are in place to minimize the likelihood and effects of a release. When selecting an Alternative Release Scenario, EPA suggests a facility consider scenarios such as transfer hose releases, valve and flange leaks, pump seal leaks, and shipping container mishaps, among others. For the Norcross hydrogen process, a credible release would be the failure of a liquid hydrogen line on the tank, with the released hydrogen gas igniting and causing a small vapor cloud explosion. At the Norcross facility, a release of this type would result in a maximum impact distance of about 0.09 miles, or 482 feet. To determine this distance, we used the Compressed Gas Association's "Risk Management Plan Guidance Document for Bulk Liquid Hydrogen Systems." In a ccordance with OSHA's Process Safety Management standard and EPA's Risk Management Program rule, the Norcross facility has a comprehensive accident prevention program in place to ensure the safety of our employees, our neighbors and the community around us. On a local level, this prevention program is built around process safety concepts such as: ? Documented process safety information to ensure the process design is understood and maintained throughout its life; ? Process hazard analysis to identify and control all of the hazards associated with handling hydrogen; ? Trained operators, using written operating procedures, to safely operate the process as intended; and ? Maintenance programs and procedures to ensure the on-going mechanical integrity of the process. The prevention program is audited periodically, by our corporate assessment group, to ensure that the process safety concepts and practices are in place and working effectively. As a result of our process safety and risk m anagement practices, the Norcross facility has not had an accident involving hydrogen in the last five years. In the event of an emergency, the facility has an emergency action plan in place, which contains procedures for employees to follow, including notification of local response agencies. All facility employees are trained in their role in the emergency action plan, and Praxair policy requires that emergency drills be conducted at least annually. Praxair is committed to continuous improvement of its safety and environmental programs. At the Norcross facility, we have recently installed additional process isolation valves to enhance our capability to shut down the process safely in the event of an incident. We have also recently upgraded our fire detection system to increase our ability to detect and respond to minor problems before they can become major incidents. |