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LCM4550 Pipe Laying Tension Monitoring

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A global provider of offshore and subsea oil field solutions contacted us about a load pin requirement for a pipe laying vessel. The company operate a fleet of lay vessels worldwide, and needed some replacement load pins for a tension monitoring system on a vessel fitted with an advanced Reel-lay system capable of both rigid and flexible pipelaying in up to 10,000 feet of water. The load pins they were looking to replace had previously been supplied by another company, but had become damaged due to a sub-standard adhesive being used to bond the strain gauges and poor water proofing. The customer was therefore looking for a new supplier that they could rely on to consistently provide quality load pins that offered long-term continuous operation.

The original enquiry was for 28 load pins, but a decision was later made to replace all load pins within the system. This comprised of 1 x 3200kN dual bridge load pin for the Aligner (with 1 spare), 4 x 450kN dual bridge load pins for the Straightener (with 1 spare) and 28 x 2500kN dual bridge load pins for the Tensioner Track (with 2 spares). Each load pin was connected to a waterproof enclosure housing two amplifiers, to give dual redundancy. The amplifier supplied a 4-20mA output which allowed connection to the vessels PLC system, to provide a complete tension monitoring system.

The pipe tension monitoring system allows pipe deformation to be controlled as it leaves the vessel through to installation on the sea bed, by keeping the pipe under tension as it moves through the various pay out equipment. The bending and axial stresses can then be kept within an acceptable range to stop excessive bending and kinking from damaging the pipe. By continuously monitoring the tension levels, the operator can make adjustments to the equipment as soon as a potential problem is identified, minimising any downtime.

The main criteria for the project were as follows:

  • Load pins must be identical to the pins they are replacing
  • Each load pin must have a separate external amplifier housed in a stainless steel enclosure rated to IP67
  • The output signal must be compatible with the vessel PLC system (4-20mA)
  • Both load pins and amplifiers must have dual redundancy to protect the system in the event of any failure
  • Complete system delivery required within 9 weeks
  • Full material traceability required

AP116

 

For this order, our design engineers needed to design three different load pins for use in the pipe laying vessels Aligner, Straightener and Tensioner. All had to be direct dimensional replacements for existing load pins and have dual redundancy to ensure system operation even in the unlikely event of one of the strain gauge bridges failing. The lead time of 9 weeks for the supply of all 37 load cells with their stainless steel enclosures was a challenge, but was achieved.

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