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Flowlines used to investigate the rate of change of can show how to improve tensioner pad slip and exhaustive test variables, such design, offering more friction coef? cient as pad size and material, pipe diameter over a wide range of track loading, even and coating type, temperature, water when challenging ? eld joints are present. presence, contamination, etc., provide It also allows a challenge to the tensioner a sound understanding of the frictional design friction coef? cients currently con- behavior and compression response. sidered. If additional friction is present,

The declining friction coef? cient with through good tensioner pad design, the increasing track loading indicates that tensioner can be designed to be shorter ef? cient pad design is required to pro- for the same top tension capacity, an

Fig. 5: Field joint passage through the vide useful levels of friction at the high effect which cascades through the whole tensioner loads necessary to have relatively short level envisaged does not exist and to real- lay spread and vessel sizing. tensioner lengths in deep water. This is ize that even small changes in a couple of particularly true when temperature varia- parameters can signi? cantly reduce the Alex MacKinnon is tion and the presence of contamination, operational margin that is available. MacKinnon Marine’s typical in spoolbase facilities, becomes In a recent test, simulating a four track managing director. present on the pipe coating, resulting in tensioner with 400-tonne capacity hold- He has more than 20 signi? cant friction reduction. In many ing a 12in. diameter pipe, two designs of years engineering cases the design friction coef? cient is not tensioner pad were tested back to back. experience and has achieved at high load, so an 800-tonne The MacKinnon Marine design returned been involved in all system may no longer hold 800-tonne. signi? cantly higher friction coef? cient aspects of subsea

Field joint coatings, typically 12.2m (circa 80%) right across the range of track engineering, including detailed design, apart, also need to pass through the ten- loading indicating that by simply chang- subsea construction, and pipelay, sioner. The radial upstand height over- ing the tensioner pads an immediate globally. He specialises in installation loads the limited suspension available performance upgrade is generated. For engineering and tensioner pad design within the tensioner, causing a severe an existing tensioner, that means more and testing. MacKinnon has a PhD in limitation on allowable track loading operational margin up your sleeve and Experimental Aircraft Aerodynamics and, consequently, the top tension that for a new build vessel the chance to ? t a from Cran? eld University. He also has a can be held. shorter tensioner. BSc in mechanical engineering from

It is sobering to learn that the friction Using the tensioner test rig simulator Dundee College of Technology.

26th International

Oil Field Chemistry

Symposium 22. to 25. March 2015, Geilo, Norway

Call for abstract 2015:

How does the application of production chemicals, production chemistry management techniques and the use of associated technology influence “Cost Assurance and Return on Investment”?

Abstract submission deadline 30 September

More information at www.tekna.no/intconf or [email protected]

Tekna – The Norwegian Society of Graduate

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