Embed Size (px)
Citation preview
www.sonardyne.com
Overcoming challenges in Mounting Metrology Equipment Subsea
Aberdeen June 2014
Peter Major
Sonardyne Survey Support Group
www.sonardyne.com
Sonardyne Metrology Stab and Receptacle
Agenda
Agenda
• Summary of metrology data collection
• Why there is a requirement for an industry standard metrology connection point
• Specific design features of the Sonardyne stab and receptacle
www.sonardyne.com
Sonardyne Metrology Stab and Receptacle
Why the requirement for an improved solution
• Metrology systems mounted on structures using a physical connection point
• No standard in place - connection points determined:
– late in design process
– or after manufacturing has begun.
• The precision and repeatability of docking into this connection affects accuracy and time
• Due to uncertainty, the estimated error determination is complex.
• Reducing QC checks saves time
www.sonardyne.com
• The most common method of collecting metrology
measurements uses a form of LBL acoustics.
• Acoustic transponders are mounted onto structures
Sonardyne Metrology Stab and Receptacle
What measuring equipment is used
www.sonardyne.com
What’s missing from this field?
Connectors
Sonardyne Metrology Stab and Receptacle
Summary of Metrology Measurements
www.sonardyne.com
1) Horizontal Distance
2) Vertical angles
or difference in
elevation (depth)
3) Pitch of the two
hubs
4) Seabed
clearance
5) Horizontal connections
require the accurate
measurement of
horizontal angles
Sonardyne Metrology Stab and Receptacle
Summary of Metrology Measurements
www.sonardyne.com
Sonardyne Metrology Stab and Receptacle
Step by Step to Acoustic Metrology
• Deploy Compatts in stands to seabed as part of an array
• Perform depth loops between structues and seabed array using
handheld depth sensor
• Place metrology Compatts/GyroCompatts in structures
• Rotate the Compatts usually to all four quadrants measuring pitch and
roll
• Possibly install other Compatts in structures for heading
determination or collect heading measurements from GyroCompatt
• Collect baselines
• Perform metrology calculations
www.sonardyne.com
The spool design modelling will consider a number of variables
• Construction and material composition of the connector
• Expansion capabilities of the connector
• Environmental loading on the connector from current and waves
• Friction between spool and seabed
• Connector design life
• Tie-in flange misalignment
Sonardyne Metrology Stab and Receptacle
Improved Error Budgets
www.sonardyne.com
The spool design modelling will consider a number of variables
Tie-in flange misalignment is derived from metrology error budgets
• Acoustic baseline measurement (inc SV measurement),
• Dimensional control errors,
• Inclinometer sensor error,
• Depth sensor error,
• Heading sensor error
• Errors in mating the metrology instruments with the structure
Sonardyne Metrology Stab and Receptacle
Improved Error Budgets
www.sonardyne.com
The spool design modelling will consider a number of variables
Tie-in flange misalignment is derived from metrology error budgets
Error budgets are not clear if precision of mating between sensor and structure is uncertain
Better appreciation of this precision will improve error budgets - resulting in the better determination of required tolerance
Higher tolerances require greater care and possibly money
Sonardyne Metrology Stab and Receptacle
Improved Error Budgets
www.sonardyne.com
Reducing the requirement to rotate Compatts for attitude measurements could save much time
Sonardyne Metrology Stab and Receptacle
Time savings
Activity Time
Deploy Stand C6 to seabed and position 45
Deploy Stand C6 to seabed and position 45
Deploy Basket to Seabed with Hub C6s 15
Install Hub 1 Beacon 10
Install Hub 2 Beacon 10
Depth Loop (4 beacons) 20
Depth Loop (4 beacons) 20
Depth Loop (2 beacons) 10
Inclinations and Ranges (2 Beacons, 1 Quadrant) 30
Inclinations and Ranges (2 Beacons, 1 Quadrant) 30
Inclinations and Ranges (2 Beacons, 1 Quadrant) 30
Inclinations and Ranges (2 Beacons, 1 Quadrant) 30
Inclinations and Ranges (2 Beacons, 1 Quadrant) 30
Array Calibration 10
Recover Stand C6 15
Recover Stand C6 15
Recover Hub C6s and Basket 15
Total 380
6hrs 20 mins
www.sonardyne.com
Sonardyne Metrology Stab and Receptacle
Different stabs and receptacles
www.sonardyne.com
• Yes – stabs and receptacles have been used for a long time
• However, they are never to the same standard so error budgeting problems remain.
• Contract to do metrology may be awarded very late in the project
• The structure may already be designed or even on the deck of a vessel heading offshore
• How can we tackle these problems?
Sonardyne Metrology Stab and Receptacle
Practical problems typically encountered
www.sonardyne.com
• The key is to have a standard receptacle transition piece
• Included in the structure design and dimension controlled survey.
• A known point to connect measuring equipment to.
• with known precision and offsets to hubs to use in the error budget.
Sonardyne Metrology Stab and Receptacle
Receptacle Transition Piece
Standard 125LW Pipe Flange
www.sonardyne.com
• Receptacle bolted into this transition piece
• Ideally installed prior to dim con for optimum results
• Or installed ‘last minute’with alignment between receptacle and transition piece verified dockside
Sonardyne Metrology Stab and Receptacle
Metrology Receptacle
www.sonardyne.com
• Our proposed stab
Sonardyne Metrology Stab and Receptacle
Metrology Stab
www.sonardyne.com
• Stab bolted onto the measuring equipment and surveyed in by the
survey company
Sonardyne Metrology Stab and Receptacle
Stab Attached to Measuring Equipment
www.sonardyne.com
• The stab can then be
mated into the
receptacle subsea
• A tell-tale flag ensures
it’s docked fully
Sonardyne Metrology Stab and Receptacle
Stab and Receptacle Mating
www.sonardyne.com
• The tell tale
• 45 degree cone
Sonardyne Metrology Stab and Receptacle
Receptacle Features
www.sonardyne.com
• The bar in the slots gives a
larger distance to enable
better heading alignment
control
• O-ring helps mating
connection
Sonardyne Metrology Stab and Receptacle
Stab Features
www.sonardyne.com
Sonardyne Metrology Stab and Receptacle
Complete Installation
www.sonardyne.com
• Sonardyne Baseline article: Technip in Egypt
• Used GyroCompatts with precise stabs and receptacles. Soon found no
requirement to perform attitude measurement rotations. Time saved!
Sonardyne Metrology Stab and Receptacle
Practical Example
www.sonardyne.com
• Design has been optimised for acoustic transponders
• But as long as receptacle transition piece has been installed, other
bespoke receptacles can be bolted on
Sonardyne Metrology Stab and Receptacle
Other Measuring Tools
www.sonardyne.com
• The next step is to get industry agreed and then ask the structure
designers to build this receptacle transition piece into all structure
designs on suitable parts of the structure
• Better communication between those designing connectors and those performing metrologies could result in designs that are easier and cheaper to measure and install
Do we all agree?
Questions?
Sonardyne Metrology Stab and Receptacle
Greater co-operations in industry
www.sonardyne.com
Review
• Summary of metrology
• Why there is a requirement for an industry standard metrology instrument connection point
• Specific design features of the Sonardyne stab and receptacle
• Practical example
Sonardyne Metrology Stab and Receptacle
Review
www.sonardyne.com
Finish
Are there structure design engineers in the audience who we can contact
to make this happen?
Peter Major
Sonardyne International Ltd
