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before the multifall/multipart rigging and safely expedite advances into tech-

Classifcation requirements evolve

EPIC

To keep pace with the rise in the use arrangement – they have to work twice nology frontiers. of heave compensation techniques, as hard for each part or fall. In general, a classifcation societies are working to typical winch based AHC system is of no Herman Stolle serves provide guidance in key design areas, real practical use on a system with more as ABS’s principle including: than two-part/fall rigging. Currently, mul- engineer for offshore • tifall/multipart rigging arrangements with Basic design requirements and safety technology and more than two falls/parts are compen- factors for general fatigue life, structure, business develop- sated using hook-mounted PHC systems. electric/ hydraulic components, lifting ment, in Rotterdam,

Regardless, PHC is not as accurate or wires and umbilicals, including routing where he has • adaptable as AHC. Considerations for shock and amplifed responsibility for

Another signifcant challenge is the structural loading due to poor synchroni- general issues on offshore lifting appli- impact of a naturally occurring catenary zation between vessel heave and the reac- ances and relevant (subsea) crane in the lift wire of deepwater operations. tion of the heave compensation system applications. Stolle has worked in •

As has been found on recent >2000m Overload mitigation should the heave Norway for 17 years in design and (6560ft) subsea operations, lift wires compensation system fail management related to offshore cranes • rarely sit vertically in the water column. Testing techniques and lifting. He attended the Polytechnic •

Slack in the wire is not eliminated by the Baseline design features, such as key Academy in Enschede, The Netherlands. weight of the load alone. The bend in the instrumentation and software features.

Lee Screaton is a Houston-based consul- line creates problems for vessel-based The role of class services continues to tant specializing in offshore equipment compensation systems because when change as the offshore industry advances and handling systems. After more than 20 they retract or extend the wire to com- into deeper water and more exacting years of design, operation and manage- pensate for vessel heave, a percentage operating environments. As E&P activi- ment roles in the oil, gas and subsea of the movement intended for the hook ties move into more challenging areas, telecoms industries, he now regularly based load is lost in the slack of the wire. classifcation societies will continue consults on existing and future equipment

When the system takes up the slack, the to transform to answer the industry’s designs for both surface and subsea result can be sudden jerky motion at the changing needs. As operating condi- operations. Lee holds a BEng (Honors) in load, shock loading through the system, tions change, the ultimate goals of the

Electronic and Electrical Engineering from confusion in the AHC control system and class society remain the same – to help

Aberdeen University in Scotland.

poor synchronization. increase uptime, improve productivity

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