D5c.1 Behaviour IPCO and Kleiss inflatable gas stoppers during ignition in pipes // D5c.2 – Effectiveness double inflatable gas stoppers

As part of the Dutch national research programme, HyDelta, a study was conducted on the suitability of inflatable gas stoppers as a fast temporary seal in a hydrogen distribution network (of the Regional Network Operators).

The study as described in this report is part of Hydelta 3.0 work package 5 “Technology & safety in the hydrogen network” and concerns the sub-research WP5C; inflatable gas stoppers. It concerns the use of inflatable gas stoppers in both incident control and planned work. Inflatable gas stoppers are also used in the transport network (of Gas Transport Services, GTS, but the application is different from the application in a distribution network. The results in this report do not relate to the application of inflatable gas stoppers in the gas transport network (> 8 bar).

Based on the research on inflatable gas stoppers as performed in HyDelta 2.0 [1] it was concluded that inflatable gas stoppers can be used as a closing device in hydrogen distribution networks. If the inflatable gas stopper is placed at a distance of more than 1 meter from the outlet opening, then additional measures are required according to the HyDelta 2.0 report [1].

The ignition tests in the above-mentioned report were, however, only performed with Kleiss inflatable gas stopper, while in the Netherlands inflatable gas stoppers of the IPCO brand are also used. The effectiveness of a proposed additional measure must also be demonstrated. In addition, the tests on inflatable gas stoppers in HyDelta 2.0 were only performed in a pipe with a diameter of 160 mm. The effects in pipes with a smaller diameter may be different. These aspects have been investigated and described in the present report.

Based on the research carried out, the following is concluded;
• The use of single inflatable gas stoppers in a hydrogen distribution network is not always safe.
• IPCO inflatable gas stoppers can be used as a temporary sealing device in hydrogen distribution networks. There are specific recommendations depending on the diameter and length of the pipe in which the inflatable gas stoppers are used. These recommendations apply not only to IPCO inflatable gas stopper, but also to Kleiss inflatable gas stopper.
• It is not necessary to insert double inflatable gas stoppers in pipes with a diameter of 110 mm or smaller. An explosive ignition of hydrogen in a pipe with a length of 20 meters and a diameter of 110 mm does not lead to the collapse of a single inflatable gas stopper. This applies to the inflatable gas stoppers of IPCO and Kleiss .
• Inserting double inflatable gas stoppers with a diameter larger than 110 mm increases safety. Even if the nitrogen purging has not yet started. However, failure of both inflatable gas stoppers cannot be ruled out. During the preparatory work for inserting the second, inner, inflatable gas stopper, undesirable events can occur. The inflated outer inflatable gas stopper can burst, a part of the inlet on the pipe can come loose and the not yet inflated inner inflatable gas stopper can break.

Since inflatable gas stoppers can still fail in a block & bleed application, it is recommended to complete the preparations for setting the two inflatable gas stoppers simultaneously. This way, both inflatable gas stoppers can be inflated shortly after each other and the nitrogen purging can be started quickly. This reduces the chance of unsafe situations.

Dit project is medegefinancierd door TKI Nieuw Gas | Topsector Energie uit de PPS-toeslag onder referentienummer TKI2023-HyDelta.