• Transport and infrastructure

Testing Orpheus in the underworld

A portable corrosion-detection device looks set to transform routine inspections for gas distributors.

James Fisher NDT has been working in conjunction with UK gas distribution company, SGN, on a bespoke inspection solution to use on its buried Orpheus regulator modules which will save considerable time and money.

Now, after a rigorous testing process, the Orpheus Bespoke Scanning Device (BSD) is in the final phases of approval and may potentially be rolled out across SGN's gas networks, which cover 5.9 million homes and businesses across Scotland and the south of England.

BSD is a portable internal corrosion-mapping scanner designed to conduct the obligatory routine inspections (aka PSSR inspections) of buried Orpheus regulator modules swiftly and in-situ.

Mike Ennis, applications specialist at JF NDT explains:

'By negating the need for time-consuming and disruptive excavations to complete the testing procedure, this system will save many man hours and thousands of pounds when in widespread use on the hundreds of systems across the network.'

Orpheus regulator modules work to filter and lower the pressure of natural gas as it leaves SGN's higher pressure network to ensure it supplies a safe and stable gas supply suitable for commercial and domestic use. In compliance with Pressure System Safety Regulations 2000 (PSSR) all of the Orpheus systems operating above 2Bar are required to undergo periodic inspections (at least every six years) to check for corrosion, but because the modules are typically buried underground, the testing procedure normally requires extensive and sometimes protracted excavation work.

During testing the systems must remain in-situ, and buried underground, making inspection a challenge, however, JF NDT's BSD scans the exterior wall of the Orpheus pressure vessel from the inside. In testing it provided more detailed data than the existing, external measurement method, which also involves excavation, allowing the inspection to be typically completed in one or two days.

Mark Skerritt, innovation project manager at SGN says:

'With support from James Fisher NDT, we've created what we think is an ideal solution to the problem of collecting corrosion information without having to excavate. What used to take several weeks now takes a few days.'

The result is a scanning system that complies with gas industry standards, that also saves time, money, reduces interruption in service and provides more detailed picture of the asset's condition. All the scanning and operator equipment fits in the back of a van, for easily transportation.

Mike adds:

'The new technique and technology will minimise inspection times and disruption to the grid, lowering the cost of testing and improving the quality of data recorded, so providing gas network operators with enhanced reassurance relating to the integrity of their buried Orpheus regulators.'

'It allows asset integrity engineers to make informed decisions about the condition of the regulators and schedule appropriate maintenance as well as accurately calculate remaining asset life.'

How the Orpheus Bespoke Scanning Device works

Following removal of the internal regulator cartridge and filter assembly by the gas distribution network (GDN) operator, JF NDT technicians lower the scanner into the housing of the gas regulator on a specially designed frame.

This holds it in place securely, so the scanner can be moved around the interior surface of the Orpheus vessel to take measurements of its wall thickness. Video cameras provide live images to the operators on site and a software system maps the resulting data to create a 3D model of the corrosion situation. JF NDT then analyses the data and provides a detailed condition report.

Watch SGN's video on the Orpheus Bespoke Scanning Device

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