Type AF Used by Deep Sea Divers 100m Below Sea Level

Lindapter’s Girder Clamps were selected by Apache North Sea subsea engineers and then installed by divers more than 100m below sea level to secure the production riser on the Forties Alpha Platform to the base support frame for the Aviat Field Development Project. The Apache structural design engineers were tasked with finding a robust connection to secure the production riser’s supporting framework. The brief required a connection that would withstand high loads and outlive the production riser, while providing a quick way for the divers to carry out the installation while wearing thick gloves underwater. Corrosion resistance and fatigue life were of paramount importance as the application needed to be able to support the weight while handling wave action on the host platform and movements from internal pressure in the production riser for over 15 years. Various conventional connections were evaluated and some were immediately rejected because the exact position of the joint was unknown whereas the adjustable Lindapter clamping systems prevented this from being a problem. The Apache engineers contacted Lindapter’s technical team and took advantage of the free connection design service. They quickly received a detailed proposal drawing of the connection detail which was secured with heavy duty M24 Type AF Girder Clamps, which are manufactured from SG iron with a hot dip galvanised coating as standard. The subsea engineers specified Lindapter’s proposed solution because it provided the tensile and slip resistance that was required for the loads anticipated during the life of the production riser. Lindapter’s clamping method simplified the design issues and the installation process and operational activities for improvements in long term reliability, such as a reduced need for inspection and maintenance. The engineers were sure that the product was the correct choice for the application due to the guaranteed safe working loads and superior corrosion resistance which is ideal for subsea applications. Further reassurance was offered by Lindapter’s range of independent approvals and over 80 years’ experience in designing and manufacturing connections. During the installation, the divers benefited from the lateral adjustability of the Type AF which allowed the framework to be quickly positioned and tightened using just simple hand tools. The subsea engineers commented on how easy, quick and simple it was to secure the application with thick gloves underwater and they will use Girder Clamps by Lindapter for future projects.

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