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Leak free connectors ensure security of gas odorising unit

16 February 2007

Staubli’s HCB couplings are providing secure, reliable, quick release connections for Robinson Brothers’ natural gas odorising systems – connections that can be made and unmade with the absolute minimum of spillage

Natural Gas does not have a characteristic smell; if the gas was used in this condition, leaks in the system could occur without detection, leading to catastrophic results. Robinson Brothers has been involved in the gas odorant business for over 40 years, manufacturing the chemicals that impart the recognisable ‘gas’ smell to alert all to the possible danger of a leak.

The company dates back to 1869 when it established a tar distillery on its West Bromwich site. The family-owned business achieved standard ISO 14001 in 2000 following the installation of a £1.4m abatement plant that treats waste products from the processes while ensuring zero environmental emissions.

Over the years the chemicals used for gas odorising have changed from tetrahydrothiophene in the 1960s to a combination of mercaptan and sulphide today. A property of this mixture is that, even when diluted to a few parts per million, it retains the smell associated with Town Gas. Consequently the handling of these chemicals needs to be strictly controlled to ensure no escape occurs that could result in a false gas leak alert. This is particularly important when the highly concentrated odour additive, which is injected into the local gas supply, is being transferred into storage tanks.

Robinson Brothers supplies gas odorant throughout the UK, and its engineers recognised the necessity of having reliable leak and odour free connectors between the odorant transfer hoses and the gas distribution sites. Staubli was called in to advise on the type of connectors they should use, as site engineering manager, Tony Quinney recalls:.

“We had good experience of the company’s quick release connectors on other high integrity applications so, when this requirement arose, they were the natural choice to advise on a dry break, reliable and robust coupling with next to no loss in containment.”

Staubli recommended a connector that had only recently been introduced to its range, the HCB 28. This flush faced, non-spill design, prevents any air inclusion in the system during connection, as well as avoiding any spillage on disconnection. The initial HCB range, introduced a few years ago, included sizes up to DN25, but in response to market demand, the range was extended up to DN80 sizes. The new, larger couplings are suitable for bulk filling duties that demand zero leakage, and they proved ideal for Robinson’s challenging gas odorisation application requirements.

All HCB connectors feature Staubli’s bayonet locking system, which provides a safe, quick and reliable connection. The locking system gives a positive feedback response, ensuring a high integrity connection. On the new, larger sizes, the coupling can be fitted with a hand-operated wheel if required.

The changeover to the new connectors at Robinson’s started in April 2005, following extensive testing. Gradually, each of the odorisation stations are being fitted with a specially developed version of the HCB 28 couplings, as well as all the hoses and equipment on their fleet of delivery vehicles. A set of HCB 28 couplings have been on test at Robinson’s for over two years. No leaks have occurred in any of them and they have significantly simplified the refilling process.

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