Scansense ensures reliable measurements with RISE

When a vessel is moored in severe weather, the forces acting on wires and chains can be extremely high. A mooring system may include several force sensors, each measuring the load on an individual wire or chain. The crew on board needs to know how heavily each mooring point is loaded and be able to act before limits are exceeded. This is one of many situations in which sensors from Norwegian company Scansense are used.

“Our customers place a very strong emphasis on quality. The equipment has to measure correctly and remain reliable for a long time – perhaps as long as 20 years – which places high demands on both robustness and reliability,” says Arve Olsen, Customer Success Manager at Scansense.

Up to 1,200 tonnes

The company has been developing and manufacturing force and torque transducers since the 1980s and primarily supplies the offshore, maritime and energy sectors. Its transducers are used in applications including mooring systems, winches and cranes, with measurement ranges from around 1 tonne up to 1,200 tonnes.

“We may be dealing with loads of hundreds of tonnes, and a measurement error of one or two per cent represents a very significant force. Things can quickly go wrong,” says Arve Olsen.

The sensors are primarily based on strain gauges, in which metal elements deform when subjected to a load. The deformation changes the electrical resistance, which can be measured and converted into a signal. But for the measurement value to be reliable, the transducer needs to be calibrated.

Scansense has its own reference transducers, which are used to calibrate the transducers supplied to customers. These reference instruments must, in turn, be checked against an even more accurate reference. This is where RISE comes in.

“We have twelve reference transducers in total, ranging from approximately 5 to 300 tonnes, which are calibrated by RISE every year,” says Arve Olsen.

This creates an unbroken chain of traceability: from the transducers used by Scansense’s customers, through the company’s own reference transducers, back to the national measurement standards at RISE.

Driving the transducers from Norway to Borås

When Arve Olsen visits RISE in Borås, he follows the calibration process at the Swedish National Laboratory for force and torque. Jan Andersson, TIC Engineer at RISE, mounts Scansense’s reference transducers in a machine capable of generating very high forces, together with RISE’s own reference force transducers.

“The machine can generate forces of up to 6 MN, corresponding to approximately 600 tonnes. The force is generated by a large hydraulic piston pressurised from below. But the quality of the measurement comes from our reference force transducers, which are themselves calibrated against a deadweight machine. During calibration, we compare the readings from our reference transducer with those from Scansense’s equipment,” says Jan Andersson.

Arve Olsen is on site because Scansense transports the reference transducers from Norway to Borås themselves. This makes it possible to limit production downtime to just two or three days.

“RISE takes very good care of us and completes the work within a very short time. We can plan well in advance and book a time that suits our production schedule. But the main reason we have chosen RISE is the high quality and low measurement uncertainty of the calibrations. It shortens the traceability chain and reduces the uncertainty in our own calibrations,” says Arve Olsen.

Creating a chain of trust

Traceability is important all the way from the equipment delivered to the customer back to the national measurement standards at RISE. It is also something required by customers, standards and specifications. But for Arve Olsen and his colleagues, reliable measurements ultimately come down to something much more tangible.

“When our customers are out in the North Sea, the sea is rough and they are lifting something while people are working on deck, they have to be able to trust that the information from the instrument is correct. Traceability creates a chain of trust that is extremely important to us,” says Arve Olsen.