Page 59: of Offshore Engineer Magazine (Apr/May 2015)

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were urgently required for the near-shore installation.

Seafex’s large rental pool is designed to cover exactly this type of urgent requirement from stock, and the lack of shipping

When it needs o go volume offered by these infatable units made for extremely cost-effective airfreight from the UK to Australia compared to up to 20 containers which would have been involved in air- from HERE freighting 750-ton of solid foats halfway around the world.

The use of buoyancy loss at depth to engineering advantage was also key to this campaign, as buoyancy was only required by Allseas to provide enough uplift of the pipeline in the top part of the water column without affecting pipeline stabil- ity on the seabed in the way that modules offering a constant amount of buoyancy would have done. Seafex modules have also played a major part on the above water tie-in: 24 x 5-ton multi-attachment infatable buoyancy modules have been used, allowing for a staged infation of buoyancy during the recovery process when required.

Where diver intervention to remove the modules from the pipeline after touchdown is not possible, tailored attach- 1,000' ment and release mechanisms are required. In 2010, a 2.3km three-pipe bundle (composed of 18, 22 and 24-in. pipelines ftted with 5-ton Seafex Mono Buoyancy Units at different spacings to cater to the different weights in water of each of these pipelines) needed to be pulled through a crocodile and 2,000' snake-infested swamp for the Angola LNG project by French to way down THERE, contractor Spiecapag. To allow for the release of the infatable buoyancy units at the end of the pull without anyone needing what’s in between to get wet, or risk getting bitten, Seacatch quick release hooks 3,000' were introduced into the rigging connecting each unit to the pipeline, to be triggered from a workboat via a lanyard secured is CRITICAL to the top of each unit.

But it is not just on classic rigid oil and gas pipelines that the

Samson’s engineered ropes replace principles of air-flled bags are bringing operational advantages 4,000' steel-wire in applications where to installation contractors around the world. They have been used on high-density polyethylene pipes as well as in applica- wire just can’t get you there.

tions such as draught reduction and uprighting jackets.

WINCH LINES

Conclusions 5,000'

Using infatable buoyancy units on shore approach work

HEAVY LIFT SLINGS could save contractors time and money on storage, transport, handling, rigging, and retrieval compared to conventional steel

EXTENSION PENDANTS or foam-flled plastic buoyancy, as well as decreasing the risk

TOW LINES profle to divers and workboats – and is thus worthy of con- 6,000' sideration by those who have yet to assess the benefts of this

WORKING LINES technology for themselves.

An ever-increasing number of contractors now adopting this kind of solution, some uncertifed. On the balance of prob- abilities, bags which carry certifcation relating to their proven 7,000' factors of safety and come with a track record of use on such projects are much less liable to result in lost time, lost time which could the cost savings made at point of purchase. 8,000'

Chris Sparrow graduated with a BA

Honors degree from the University of

Durham, UK, in 1995, and has worked in

International Sales and Marketing ever since. His early career was with Fluke 9,000'

Corp. within the feld of industrial electron- ® ics. He has specialized in offshore fotation

SamsonRope.com

Dyneema is a registered trademark of Royal DSM N.V. Dyneema is DSM’s high-performance polyethylene product.

since 2002, when he joined Fendercare to front up their Hippo Marine solid buoyancy division. Chris

See us at OTC NRG CENTER #5505 joined Unique Seafex in March 2013.

10,000' oedigital.com April 2015 | OE 60 058_OE0415_Pipelines2_Unique.indd 60 3/23/15 6:30 PM