A new flexible riser integrity monitoring system from Pulse Structural Monitoring has achieved a 100% success rate in a rigorous and ground breaking dynamic test process.
FlexASSURE uses non-invasive sensors to detect breaks in the tensile armour wires of a flexible riser, building a detailed picture of structural integrity and alerting the user to early signs of deterioration.
It was conceived in response to calls from operators for a reliable means of validating riser integrity in deepwater installations, following a number of riser failures in recent years.
The system, comprising monitoring hardware, a real-time data acquisition system and data processing interface, has been developed, tested and qualified in Brazil, where flexible risers are responsible for transporting approximately 80% of offshore production, amid increasingly challenging conditions.
FlexASSURE can be installed on a new riser to provide integrity assurance throughout its lifetime, or retrofitted to an existing riser where there may be concerns over its remaining life.
The FlexASSURE concept
When a tensile armour wire breaks, load is transferred from this wire to the remaining armour wires. During this event, the flexible riser experiences a sudden movement with axial, rotational and acoustic characteristics, which FlexASSURE detects using a combination of 5 sensors and a sophisticated algorithm.
The system was extensively qualified over three years, undergoing laboratory and offshore testing before progressing to a full-scale dynamic test, in which it was attached to a riser and subjected to loads representing 100% service life, accounting for 10x safety factor. This activity was monitored in a blind test, in which FlexASSURE detected 100% of the wire breaks, with no false alarms.
Richard Kluth, Managing Director, said, "Measuring the integrity of riser armour cannot be achieved using inspection methods, as the wires are internal to the flexible construction.
"Historically this has made monitoring flexible risers very difficult and, as we have seen from industry reports such as Sureflex, there are increasing concerns over leakage into the annulus and potential corrosion of armour wires.
"With FlexASSURE Pulse has a unique product that can provide early warning detection if the integrity of these critical components is compromised."
Priscilla Elman, Business Development Manager for Pulse in Brazil, said, "Their unique ability to withstand motion and ease of installation make flexible risers a favourable solution compared to conventional rigid risers.
"However, integrity issues have driven demand for effective monitoring systems and riser qualification processes to guarantee operational safety.
"Pulse's test-proven FlexASSURE solution offers operators and fabricators a highly accurate means of managing riser integrity, reducing risk of human, environmental and material losses."
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