METHANE TRANSFER LINE

Project name: Methane Transfer Line

Location: Oxfordshire, UK

Client name: ISIS/Science and Technology Facilities Council (STFC)/UK Research and Innovation (UKRI)

Sectors: Cryogenics

Year of completion: 2019

ISIS Neutron and Muon Source is a cutting-edge, government-funded research facility based at the Rutherford Appleton Laboratory in Oxfordshire. Its highly specialised instrumentation allows materials to be examined at an atomic scale, giving scientists a unique insight into their make-up.

Following a successful competitive tender, we took on responsibility for cryogenic parts manufacture at this Oxfordshire research facility. Our role was to design, manufacture and supply a vacuum-insulated transfer line mainly fabricated from stainless steel, consisting of five concentric pipes containing methane in liquid and gaseous states and tertiary layers of helium gas, each separated by vacuum (see diagram below).

Client requirements

The transfer line was to be used in materials research experimentation, connecting the cold box to the methane moderator. Consistent quality of individual parts and the system as a whole was crucial, as well as a strong performance at low temperatures, since the line was around 14m in length and was to be used to supply liquid methane at a temperature of 110K.

Constraints and solutions

The new parts were replacing components that had been in place for over 30 years, and had to align with a number of existing interface points. To add to the complexity, the area was only accessible via remote manipulator arms. To avoid potential issues with alignment, we opted to build flexibility into our design, and worked with the client to research and develop different solutions to allow adjustment of flexible connecting points by loosening a series of nuts. After design sign-off, an initial section was manufactured and tested to ensure a compliant performance, after which the go-ahead was given for all components.

Another key constraint was the insulation, since the client’s specification ruled out the organic materials we would conventionally use for insulating spacers. Following research into a range of other materials, our solution, incorporating glass spheres, stainless-steel wire and basalt fibre, achieved extremely low heat loads. For the same reason, we opted for aluminium multi-layer insulation instead of the usual combination of nylon and polymer.

The results

The client had stipulated a maximum heat load of 60W – our solution achieved 17W, and the line passed helium leak testing with a leak rate of 5×10^-12 mbar l/s. At this leak rate, it would take a cigarette lighter over a million years to lose all of its gas.