Page 45: of Offshore Engineer Magazine (Jul/Aug 2013)

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Production corrosion of rope and chain) joint and control of hardware manufacture, bring an increased need to understand industry project, says Majhi. However, but a lack of detailed oversight of it. the “novelty” of going in to deep water. there is still a lot of room for improve- Dedicated, technically competent “The tension is higher and we are ment, from the design phase through inspectors are needed to oversee com- going in to high-pressure environments procurement, installation and opera- pliance, he says. This includes dur- and using longer mooring compo- tion and having technically competent ing testing of materials, such as heat nents,” says Ma. “We should encourage oversight. Mooring system inspection, treatment, where control of the process joint industry projects and share les- for example, varies widely, from annu- can directly impact test results, and sons learned openly, without identify- ally to every fve years. non-destructive testing (NDT) beyond ing facilities.” “During mooring design, handling Class requirements. Majhi’s conclusion is a little more and installation, there is very little During installation, mooring hard- pragmatic: “It is prudent to anticipate interface and if it does happen, it is ware, deck equipment, and monitor- failure and be prepared.” late in the game. If companies try to ing equipment needs to be correctly have a feed-back loop, you fnd there specifed and in-situ maintenance are gaps in manufacturing, gaps in and replacement of deck equipment

Eight major incidents installation.” Closing these gaps would planned in. “Having spare equipment known to the authors of paper take the industry in the right direction, is one of the big savers when offshore,

OTC-24025-MS in the 10 year he says. you need to expect there is going to be period from 2001 to 2011: “One of the big challenges is damage of some critical component,” interface, ensuring early and eff- says Majhi. “You also need to have a

Banff – 5 of 10 lines parted. 2011 cient engagement,” says Majhi. It’s good deck-handling protocol so you do 2011 Volve – 2 of 9 lines parted, no also important to ensure that design not damage sheathing before you put it damage to riser. methodology assumptions are cor- in the water.” rect, refecting worse-case scenarios. Once installed, there is a risk the 2011

Gryphon Alpha – 4 of 10 lines

He says adequate modeling should be mooring system is “out of sight and out parted, vessel drifted a distance, riser carried out, and that once installed, of mind,” instead of being subject to a broken. systems should be re-analyzed. “One good inspection protocol and condi- 2010 Jubarte – 3 lines parted of the biggest gaps is re-analysis of tion assessment with data fed back for between 2008 and 2010. as-built systems; if information is future projects and code enhancement, captured, it is not put back into to says Majhi. During one failure investi-

Nan Hai Fa Xian 2009 – 4 of 8 lines mooring analysis,” says Majhi. The gation, it was discovered that the crew parted; vessel drifted a distance, riser procurement and manufacturing phase on the vessel did not have any kind of broken. needs to be closely managed, to make monitoring system and they did not

Hai Yang Shi You 2009 – Entire sure design specifcations are followed- realize they had a mooring failure until yoke mooring column collapsed; vessel through and that strength, fatigue and they saw a fxed platform nearby mov- adrift, riser broken. corrosion protection verifcation is ing away from them, says Ma. carried out, he says, as compliance On an industry level, Ma says that Liuhua – 7 of 10 2006 (N.H.S.L.) “varies widely” and there are often engineering standards should be lines parted; vessel drifted a distance, multi-layered contracts. In addition, updated and developed to “raise the riser broken. materials used should be traceable for bar” industry-wide. Work is being

Girassol 2002 buoy – 3 (+2) of 9 future testing. carried out based on API standards to lines parted, no damage to offoading

He said there is a reliance on Class agree on new codes, he says, adding designations for quality assurance that the move to deeper waters will lines (2 later).

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