Mooring Tensioning Systems for Offshore Platforms: Design, Installation, and Operating Considerations
Why this work is in the frame
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Bibliographic record
Abstract
Abstract Mooring tensioning systems for offshore floaters have evolved from rotary windlasses on ships into multiple options nowadays. These options include fixed or movable winches, either linear or rotary, driven by electric or hydraulic, and the most recent in-line tensioners which remove the on-vessel equipment. Selection of a tensioning system directly affects mooring performance and installation, hull design, as well as overall project cost, schedule, operability and reliability. This paper compares a combination of seven types of tensioning system for the mooring system of a deepwater platform. The options under consideration for the tensioning system include fixed or movable, electric or hydraulic driven, and on-hull or in-line tensioner. The pros and cons of different alternatives are evaluated in terms of design, installation, and operating considerations, and are compared against criteria including Technology Readiness, Cost and Schedule, Installation, Layout, Maintenance, In-service Tension Adjustment, HSSE (Health Safety Security Environment) Risk, and Track Record. It is found that all options, fixed or movable, electric or hydraulic driven, and on-vessel or in-line tensioners have their advantages and disadvantages, and need to be evaluated systematically to fit different projects’ needs. Fixed hydraulic chain jacks remain the most popular choices for production semis, with 12 applications out of 24 since the year 1994. Movable options have merits over fixed ones in capital expenditure, especially with high numbers of lines. However, movable options require extra equipment and operations to relocate the tensioning system and thus have shortcomings in mooring installation, tension adjustment, and HSSE risk. An electric option has advantage in maintenance, because it does not require a HPU and has no hydraulic oil or flexible pipes to be replaced. However, electric options are heavy and large, with complicated gear boxes, and require a specialized team. Without on-hull tensioning and handling systems, the in-line tensioners may significantly reduce capital expenditure. Additionally, they eliminate the notorious problem of splash-zone corrosion since the top chain is completely submerged underwater. However, this system requires surface vessel intervention for tensioning and re-tensioning, and increases project execution and schedule risk. All of these need to be taken into consideration starting from early through execution phases of projects. As the offshore industry moves forward with emerging new technologies, projects usually involve multiple choices as well as technical uncertainties and financial risks. Most projects with mooring systems will encounter the similar challenges on selecting a reliable and cost effective tensioning system. This paper can serve as a reference for a major capital project that is going to select the most suitable tensioning system. With the state-of-the-art information and industry practice on mooring tensioning systems, this paper can also service as a reference for updating new versions of API and ISO station-keeping codes.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it