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by Katie Reid on Thu, Apr 15, 2021 @ 13:04 PM
Oxygen is used in steelmaking and metals refining, petroleum processing, chemicals, pharmaceuticals, and other manufacturing processes. Industrial engineers can't eliminate the chance of oxygen system fires, but can manage ignition risk with proper materials selection and other rigorous measures.
Earlier this month, Dr. Robert Bianco, leading materials expert and technical lead for Swagelok’s Additive Manufacturing Program, discussed best practices for component selection, materials of construction, and fabrication methods for such systems. You can access a recording, along with documents provided to attendees, here:
Watch the briefing to learn the background of oxygen applications, hazards and issues with oxygen, material selection solutions, cleanliness requirements, and relevant regulatory standards. Along the way you'll see photos of destroyed components, including a stainless steel 40G Series ball valve (2500 psig oxygen), stainless steel tee, and stainless steel rising plug valve; as Dr. Bianco steps through possible ignition mechanisms such as adiabatic compression, particle impact, and flow friction.
In certain conditions, he explains, "materials become easier to ignite because the flammable ranges start to expand, and their auto-ignition temperatures begin to drop. Even 316/316L stainless steel can become flammable."
A compressed air system is considered oxygen-enriched if it is over 23.5% concentration. Chemical reactions occur more easily at higher pressures and temperatures; and, Dr. Bianco points out, generally "hazards in oxygen systems increase as pressure increases, temperature increases, cleanliness decreases, oxygen concentration increases, and flow increases."
Fires in the atmosphere can be prevented by removing one of the three elements [oxidizer, fuel, and ignition energy], but they are inseparable in an oxygen system. The oxygen is contained within the system, usually under substantial pressure. The valves, regulators, piping, fittings, and other components that contain the oxygen are, in fact, the fuel. -- from Swagelok's Technical Bulletin, Oxygen System Safety
Reducing risk depends on removing or reducing one or more of the following factors: the oxidizer (oxygen, chlorine gas, nitrogen oxides), heat (e.g. adiabatic compression heating, particle impact, etc.), and/or fuel (metals and soft seals).
Oxygen in industrial gas distribution systems
The primary function of an industrial gas distribution system is to lower the pressure of gases between their source and their point of use. The design of and components used within a gas distribution system must be carefully selected to ensure trouble-free operation.
Safety also depends on matching components to purpose and application. For example, a ¼-turn ball valve and a multi-turn needle valve may carry the same ratings, but are designed for different purposes and applications. Ball valves are a good fit for most systems, but using a fast-acting, ¼-turn valve within an oxygen system can lead to large pressure spikes and the potential for hazardous conditions.
And, like relief valves and pressure regulators, a gas distribution system needs the right pressure control valves—ones sized to handle all potential pressures and flows. Operator safety and system reliability depend on it.
Click below to get a replay Dr. Bianco's technical briefing along with recommended reading, all in one step:
Learn about the Swagelok Gas Distribution Program
Backed by 70-plus years of fluid system expertise and a global network of pressure control advisors, Swagelok offers a two-pronged solution: pressure control advisory services and gas distribution systems that help ensure facilities are operating safely and efficiently.
Click above to get an overview of the program and take a collection of resources, including application guide.
(Need technical help right now? Call our 24x7 Field Advisory Services On-Call Technical Support: 780-237-7109.)
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