D1B.2 Safety during maintenance works for hydrogen gasstations

In the context of the national research program HyDelta, research has been carried out into the necessary mitigating measures for the commissioning and decommissioning of (hydrogen) gas stations.

During the commissioning and decommissioning of gasstations, there are situations in which gas is released. There are mitigating measures for the distribution of natural gas that must prevent damage and/or injury from occurring or limit the damage and/or injury. The question is whether it is necessary in the case of hydrogen distribution to adapt or supplement the mitigating measures for natural gas distribution stations.

In the HyDelta work package 1B “Gasstations”, this concerns the following questions;

208 – Which mitigating measures (VWIs) are necessary for the commissioning and decommissioning of (hydrogen) gasstations?

209 – Can the pressure be relieved safely if a safety risk has arisen?

On the basis of discussions with the network operators, an inventory of the various situations in which gas is released has been created. The amount of hydrogen that is released was then determined by means of calculations.

Based on the calculations and previous research, the following has been concluded;

For a safe commissioning and decommissioning (including pressure relief after a safety interference) the following mitigating measures are necessary;

Use the mitigating measures described in VWIs G-51, G-52, G-53 and G-54. Use suitable hydrogen gas detection equipment and suitable anti-static clothing.

In addition to the requirements for vent/flare installations, as described in NEN 7244-7, implement the following measures:

• Use a hydrogen flame arrester when flaring and when venting.
• Make sure that there are no obstacles in the immediate vicinity of the flare or venting point.
• Maintain a distance between the outlet point and possible ignition sources of 2 to 3 greater than with natural gas. (indicative distance of 7 metres, field research is necessary to verify).

Avoid gas outflows directly on the installation, use a vent/flare installation when depressurising the gas control installation completely.