The Working Group (WG) 15 met for the first time on May 19, 2010 in Essen, Germany.

The draft scope was discussed. The standard will cover pressure vessels (e.g. cylinders and tubes) intended for the stationary storage of gaseous hydrogen of up to a maximum water capacity of XX,000 L and a max pressure of 110 MPa, of seamless metallic construction or of composite construction. The volume is under discussion as there is a need to cover volumes that are likely to be used. The United Nations definitions of "tubes" and "cylinders" specify volume. If WG 15 wants to include up to 10,000 L, another term such as "tanks," "receptacles" or "pressure vessels" may be needed. A limit of 10,000 L may not be sufficient as there are much larger tanks in construction. This covers the cylinder or tube – a component – rather than a system, or bundle. Manifolds are not covered.

There were several participants who are also active in ISO/TC 58. It was noted that TC 58 will probably take this document and modify it for other gases. The WG noted it may be useful to get an agreement that the draft would be passed on to TC 58 to be expanded to other gases.

The general approach of the work is to develop design, manufacturing, and testing requirements for tubes and cylinders intended for a specified stationary service, starting from design and testing requirements covering tubes and cylinders used as transportable pressure vessels.

The work is not starting necessarily to approve for stationary use cylinders and tubes that are presently approved for transportable use. WG 15 wants to develop the requirements based on stationary use, and then look at whether the existing vessels that are approved for transportable use meet the requirements. However, it was noted that much information from requirements for transportable cylinders may be used in the development of this work.

Task groups were formed to address conditions of use, composite cycling and composites stress rupture, and hydrogen embrittlement.

At its March 2011meeting, the Working Group addressed:

• Terminology

• Effect of pressure variations

• Resistance to static load and lifetime

• Hydrogen enhanced fatigue of metal components (type 1 cylinders, metallic liner, metal boss)

• Plastic liner blistering and collapse

• Overheating or overcooling of the structure due to excessive rate of pressurization / depressurization.

The next meeting in July 2011 will address:

• Stress ratios

• Specified service & life cycles

• Stress rupture & hydraulic cycling tests

• Resistance to fire conditions.