- •Introduction to the Anchor Handling Course
- •Technical Specifications:
- •Winch Layout:
- •Power Settings / Bollard Pull
- •All operations on board must be performed in accordance with Company Procedures.
- •Risk Assessment
- •Planning
- •Planning:
- •Goal, example:
- •What to do:
- •Electrical winches
- •Winch operation
- •General Arrangement
- •A/H-Drum at full Capacity
- •Over speed
- •Water brake
- •Band brake
- •QUICK & Full Release
- •Hydraulic Winches
- •Lay out (B-type)
- •Hydraulic winch, “B-type”
- •TOWCON
- •Instruction for use of Wire Drums
- •Changing of Chain Wheels (Wildcats / Chain Lifter)
- •TRIPLEX - SHARK JAW SYSTEM.
- •Operation
- •Maintenance and inspections
- •Safety
- •2. OPERATION:
- •QUICK RELEASE:
- •EMERGENCY RELEASE:
- •CONTROL PANEL
- •Marks for Locked on Hinge Link
- •2.2- OPERATION OF THE "JAW IN POSITION ACCEPT" LEVER:
- •2.3 OPERATION OF THE CONTROL PANEL AT EMERGENCY POWER.
- •3. ELECTRIC AND HYDRAULIC POWER SYSTEM.
- •3. 1. ARRANGEMENT OF SYSTEM.
- •3.2. FUNCTIONING OF QUICK RELEASE - JAWS ONLY.
- •3.3. FUNCTIONING OF EMERGENCY RELEASE
- •4.2 Test without Load.
- •4.3 Test with Load.
- •5. General Maintenance
- •5.1 Accumulators Depressurising
- •5.2 Shark Jaw Unit
- •5.3 Guide Pins Units
- •5.4 Hydraulic System
- •5.5 Electric System
- •6. Control Measurements / Adjustments.
- •6.2 Adjustment of inductive proximity switches on lock cylinders.
- •6.3 Adjustment of Pressure Switches for Lock Pressure.
- •7. Test Program – Periodical Control
- •7.2 Checking List – Periodic Control Mechanical / Hydraulic.
- •7.3 Checking List – Periodic Control Electrical
- •7.4 Testing without Load – Yearly Testing.
- •7.5 Load Test – Emergency Release – 5 Year Control.
- •“Mark on line !”
- •“Double set of Jaws, Pins and Wire lifter”
- •View from the bridge.
- •“JAW READY FOR OPERATION”
- •“JAW LOCK POSITION ACCEPTED”
- •KARM FORK – SHARK JAW SYSTEM.
- •Wire and chain Stopper
- •Inserts for KARM FORK
- •Martensite:
- •Recommendations:
- •1. THE BASIC ELEMENTS OF STEEL WIRE ROPE
- •2. STEEL WIRE ROPE CONSTRUCTIONS
- •3. SPECIAL STEEL WIRE ROPES
- •4. USE OF STEEL WIRE ROPE
- •5. SELECTING THE RIGHT STEEL WIRE ROPE
- •6. ORDERING STEEL WIRE ROPE
- •7. STEEL WIRE ROPE TOLERANCES
- •8. HANDLING, INSPECTION AND INSTALLATION
- •9. INSPECTION AND MAINTENANCE
- •10. ELONGATION AND PRE-STRETCHING
- •11. OPERATING TEMPERATURES
- •12. MARTENSITE FORMATION
- •13. END TERMINATIONS
- •14. SOCKETING (WIRELOCK)
- •15. DRUM CAPACITY
- •16. CLASSIFICATION AND USE OF STEEL WIRE ROPE
- •17. ROPES
- •18. CHAINS AND LIFTING COMPONENTS
- •19. TECHNICAL CONVERSION TABLES
- •SWIVEL
- •MoorLink Swivel
- •Pin Extractor
- •Socket Bench
- •Chains and Fittings
- •STUD LINK MOORING CHAIN
- •OPEN LINK MOORING CHAIN
- •KENTER JOINING LINKS
- •PEAR SHAPE ANCHOR CONNECTING LINK
- •DETACHABLE CONNECTING LINK
- •D’ TYPE JOINING SHACKLES
- •‘D’ TYPE ANCHOR SHACKLES
- •SHACKLES
- •JAW & JAW SWIVELS
- •BOW & EYE SWIVELS
- •MOORING RINGS
- •FISH PLATES
- •PELICAN HOOKS
- •SLIP HOOKS
- •‘J’ CHASERS
- •PERMANENT CHASERS
- •DETACHABLE PERMANENT CHAIN CHASERS
- •PERMANENT WIRE CHASERS
- •‘J’ LOCK CHAIN CHASERS
- •The way to break the anchor loose of the bottom is therefore:
- •Table of contents
- •Introduction
- •General
- •Mooring systems
- •Mooring components
- •History of drag embedment anchors
- •Characteristics of anchor types
- •History of vryhof anchor designs
- •Criteria for anchor holding capacity
- •Theory
- •Criteria for good anchor design
- •Aspects of soil mechanics in anchor design
- •Soil classification
- •Fluke/shank angle
- •Fluke area
- •Strength of an anchor design
- •Anchor loads and safety factors
- •Anchor behaviour in the soil
- •Proof loads for high holding power anchors
- •Anchor tests
- •Soil table
- •Practice
- •Introduction
- •Soil survey
- •Pile or anchor
- •Setting the fluke/shank angle
- •Connecting a swivel to the Stevpris anchor
- •Chasers
- •Chaser types
- •Stevpris installation
- •Laying anchors
- •Retrieving anchors
- •Anchor orientation
- •Decking the Stevpris anchor
- •What not to do!
- •Racking the Stevpris
- •Deploying Stevpris from the anchor rack
- •Boarding the anchor in deep water
- •Ballast In fluke
- •Chaser equilibrium
- •Deployment for permanent moorings
- •Piggy-backing
- •Piggy-back methods
- •Stevmanta VLA installation
- •Installation procedure
- •Stevmanta retrieval
- •Double line installation procedure
- •Stevmanta retrieval
- •Double line installation with Stevtensioner
- •The Stevtensioner
- •The working principle of the tensioner
- •Measurement of the tensions applied
- •Umbilical cable and measuring pin
- •Break - link
- •Duration of pretensioning anchors and piles
- •Handling the Stevtensioner
- •General tensioning procedures
- •Hook-up
- •Lowering
- •Tensioning mode
- •Retrieving
- •Supply vessels/anchor handling vessels
- •Product data
- •Introduction
- •Dimensions of vryhof anchor types
- •Proof load test for HHP anchors (US units)
- •Dimensions of vryhof tensioners
- •Proof load/break load of chains (in US units)
- •Chain components and forerunners
- •Connecting links
- •Conversion table
- •Mooring line catenary
- •Mooring line holding capacity
- •Shackles
- •Wire Rope
- •Wire rope sockets
- •Thimbles
- •Synthetic ropes
- •Mooring hawsers
- •Main dimensions chasers
- •Stevin Mk3 UHC chart
- •Stevin Mk3 drag and penetration chart
- •Stevpris Mk5 UHC chart
- •Stevpris Mk5 drag and penetration chart
- •Stevmanta VLA UPC chart
- •Introduction
- •Propulsion system
- •Propellers
- •Thrusters
- •Rudders
- •Manoeuvring
- •Current
- •Wind
- •Other forces
- •Turning point (Pivot point)
- •Ship handling
- •General layout Jack-Up drilling unit:
- •General information about a Semi Submersible drilling unit:
3
Practice
Introduction
Practice |
|
Although theoretical knowledge of anchors is essen- |
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tial for good anchor design and selection, the practi- |
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cal issues are just as important. The handling of an |
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anchor and the selection and use of support equip- |
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ment is of equal importance. |
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Anchor handling is a critically important and often |
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complicated process. It is influenced by such factors as |
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the weight and shape of the anchor, the nature of the |
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soil, the depth of the water, the weather conditions, |
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the available handling equipment and the type and |
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weight of mooring line. It is for these reasons that |
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anchor handling is a subject which requires careful |
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consideration. Without proper anchor handling, opti- |
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mal performance of an anchor is not possible. |
51 |
In the process of handling anchors, various types of support equipment are necessary or beneficial. An anchor manual would be incomplete without consideration of these auxiliary items, the reasons for their use, their operation and the advantages and drawbacks involved.
This chapter gives an overview of the recommended procedures that should be followed for anchor handling and the types and use of the support equipment during the handling operations.
The following handling procedures are by no means complete, but they do give some suggestions which can be applied to each anchor handling procedure and adapted for specific circumstances and locations.
Some of the topics covered in this chapter are: requirements for a soil survey, connection of the anchor to the mooring line, chasers, handling the Stevpris anchor, handling the Stevmanta anchor, the Stevtensioner, anchor handling/supply vessels.
Soil survey
For the dimensioning of drag embedment anchors, the availability of site-specific soil data is important. For advice on specifying drag embedment anchor type/size and calculating expected behaviour, the site-specific soil data should be compared with soil data of previous drag embedment anchor (test) sites.
The soil survey requirement for the design of drag embedment anchors usually consists of only shallow boreholes, while in anchor pile design deep boreholes are required. For suction anchor design therefore a more extensive soil investigation is generally required when compared to drag embedment anchors. When choosing between anchor pile, suction anchor and drag embedment anchor the financial implications of the soil survey should be taken into account.
52
A typical soil survey for drag embedment anchor design requires a survey depth of twice the length of the fluke in sand and 8 times the fluke length in very soft clay. In most cases a depth of 8 to 10 meters is sufficient, although in very soft clay a reconnaissance depth of 20 to 30 meters should be considered. For optimal drag embedment anchor dimensioning, each anchor location should ideally be surveyed. The soil investigation can consist of boreholes, vibrocores, cone penetration tests or a combination of these. Cone penetration tests including sleeve friction are preferred, but they should be accompanied by at least one vibrocore or sample borehole per site to obtain a description of the soil. Depending upon the type of survey performed and the soil conditions encountered, the survey report should present the test results obtained on site and in the laboratory including the points as shown in table K.
It is possible to dimension the drag embedment anchors based on limited soil information (for instance fewer boreholes). The ‘lack’ of soil data can be compensated by choosing a conservative (larger) anchor size.
Typical contents survey report
•Cone penetration resistance.
•Sleeve friction.
•Pore pressure.
•SPT values.
•Granulometry and percentage fines.
•Wet and dry densities.
•Water content.
•Drained and undrained triaxal tests.
•Undrained shear strength, also remoulded.
•Unconfined compression tests.
•Plasticity limits.
•Specific gravity.
•CaCO3 content.
•Shell grading.
•Angularity and porosity.
•Compressibility.
•Cementation.
•Normalised rock hardness test (point load test).
•RQD index, rock quality designation.
table K