Offshore Gas Measurement

FLUXUS® overcomes wall thickness limitations

A large oil company operating offshore in the Asia-Pacific region called on FLEXIM to help with flow measurement in a 152.4 mm (6 inch), schedule160, thick walled pipe carrying natural gas for injection at 70 bar. Due to the installation of a new compressor control scheme, an additional flow measurement point was required to be installed on each compressor outlet. High pressure and the fact that a process shut down for installation works was not possible, other flow measurement technologies were not considered.

A FLUXUS® G704 clamp-on ultrasonic gas flow meter from FLEXIM turned out to be the perfect solution. The operator required the flow computer to be installed in a separate equipment room, therefore, ruggedised stainless steel transducers were installed remotely in the field. Connections to the transducers are made through a local junction box which galvanically isolates the transducers potential from the FLUXUS® G704 in the equipment room. Furthermore, the field equipment is tropicalised with additional surge arresters to protect against lightning strikes.

FLEXIM’s clamp-on transducer family makes use of different ultrasonic signal techniques resulting in some distinct benefits. These transducer designs allow the meters to work over a wide range of applications with little regard for variables such as wall thickness and process conditions.

This demanding high pressure gas application required a wall thickness of 25 mm (0.98 inch). However, this proved no match for the FLUXUS® G704 flow measurement system in combination with the correct transducer design.

Pressure and temperature inputs in the G704 can be activated to allow the integrated flow computer to calculate compensated mass gas flows.

FLUXUS® overcame the following challenges:

• No susceptibility to abrasive wear

• Thick pipe walls

• Exotic pipe materials

• High turndown and broad measurement range