Last edit: 25/08/2026
ISO/TR 15916 is an international technical report that provides guidelines for the safety of hydrogen systems. The document is a reference for designers, manufacturers, and end users, with the aim of supporting the safe development of technologies based on this energy carrier.
Hydrogen is playing an increasingly important role in the energy transition thanks to its potential contribution to emission reduction and its suitability for use across a wide range of industrial and energy applications. For this reason, it is considered one of the key technologies in the transition towards sustainable energy systems. However, like any energy source, it has specific characteristics that require proper understanding and careful management from a safety perspective.
Hydrogen Applications
ISO/TR 15916 considers the entire hydrogen value chain, including production, storage, transportation, and end-use applications. The technical report highlights how this energy carrier can be used in a wide range of applications, from industrial infrastructure dedicated to distribution and storage to energy generation systems and mobility solutions.
The standard reviews the main technologies used for hydrogen production, including both industrial processes and water electrolysis-based systems. It also emphasizes that different production methods may involve different characteristics and safety requirements that must be considered during plant design and operation.
The technical report describes the main solutions for hydrogen storage and transportation, including high-pressure compressed hydrogen, cryogenic liquid hydrogen, and other storage technologies. It also presents the main components of hydrogen systems, such as storage vessels, piping, valves, pressure regulation systems, overpressure protection devices, and leak detection systems.
ISO/TR 15916 also addresses the various end-use applications of hydrogen, ranging from fuel cell systems to industrial and energy applications, as well as mobility solutions.
Hydrogen Properties
Hydrogen is a colourless, odourless, and non-toxic gas, characteristics that make potential releases difficult to identify without dedicated detection systems. At the same time, it is the lightest of the commonly used gases and therefore tends to disperse rapidly upwards when released in open environments.
Another important property is its high capacity for diffusion and permeation. Due to its extremely small molecular size, hydrogen can pass through materials and sealing systems more easily than many other gases, making the proper design of storage vessels, piping, and equipment particularly important.
The standard also highlights the combustion characteristics of hydrogen. Compared to other fuels commonly used in industry, hydrogen is characterized by a wide flammability range and a very low minimum ignition energy. These properties make it essential to pay particular attention to leak prevention and the control of potential ignition sources, since accidental releases may result in jet fires, flash fires, or, under certain conditions, explosive events.
Particular attention must also be given to liquid hydrogen, which is stored at extremely low cryogenic temperatures. Under these conditions, specific hazards may arise, including cold burns and potential asphyxiation risks.
These properties make proper system design essential for safe operation.
Queste proprietà rendono fondamentale una corretta progettazione dei sistemi, per operare in sicurezza.
Safety Considerations for the Use of Gaseous and Liquid Hydrogen
The risks associated with hydrogen depend not only on its physical and chemical properties, but also on the operating conditions, the quantities involved, and the methods of storage and use.
The standard draws attention to aspects such as combustion management, material compatibility, and the prevention and detection of leaks. It also emphasizes the importance of understanding hydrogen behaviour in the event of an accidental release, considering its high diffusivity and its potential accumulation under specific environmental conditions. For liquid hydrogen systems, particular attention must be paid to the risks associated with cryogenic temperatures, volume changes resulting from phase transitions, and potential overpressure conditions generated by product evaporation.
ISO/TR 15916 promotes an approach based on risk prevention and mitigation, through proper system design, the implementation of monitoring and control systems, the use of compatible materials, and the development of appropriate operational and maintenance procedures. Particular importance is also placed on personnel training and the development of a strong safety culture.
Finally, the standard emphasizes that safety should be considered throughout the entire lifecycle of the system, from initial design through operation, maintenance, and the management of potential emergency situations.
