Efficient retrieval and seafastening of concrete mattresses
Nils Olav Åkre Hauge, Ole Kristian Lund og Mathias Meek
Background
• 40 000 concrete mattresses in the North Sea• Protect pipelines and infrastructure
• Falling objects• Trawler/anchor• Erosion
• Termination plan 5-2 years before the lie expires
The scope of this project
• Safe and cost-effective method• Without use of divers• Without using mattresses loops over water• ROV friendly• No damage to personnel or equipment
• Seafastening on board Edda Freya• Make the most out of the deck space
Existing methods of retrieval and seafastening
• Retrieval• Reverse installation• «IMF»• Speed Loader• Wet Storage/Recovery Basket• Subsea grab• Subsea Container
• Seafastening• Base frame and a Speed Loader• To Speed Loaders• Twistlock
Own methods of retrieval and seafastening
• Retrieval• Further development of the «IMF»• Further development of «Wet Storage/Recovery
Basket»• Roller Method
• Seafastening• Power screw• Bolts
The evaluation process
• Efficiency• Safety• Cost• Manageable• Seafastening• Structure
• Further development of the «IMF», combined with Twistlock
Relevant regulations
• The law of petroleum (PTIL)
• DNVGL-ST-E273
• NS-EN 1993 Eurocode 3
• NORSOK R-002
• Norwegian Maritime Code
• DNV – Rules of Classification of Ships
• Traffic rules
Selected method
• Lifting frame• «VI-SO Clamp»
• Container• «Twistlock»
Rigging
• Hand Calculations• Shackle• Pad eye• Weld• ROV hooks• Straps
• Ansys• Pad eye• VI-SO Clamp
Structure Calculations
• Hand Calculations• Buckling Calculation
• SAP2000• Lifting Frame• Container
Seafastening
• Mathcad• Twistlock
Conclusion/Suggestions for further work
• Time- and cost effective method• Expensive investment cost• Satisfying all requirements provided by DeepOcean• Develop a new «VI-SO Clamp» with higher load capacity
Mass (kg)MaterialRevDescriptionQtyItem
1800,3Steel, Mild 350x250x16 L=6468211253,1Steel, Mild 350x250x16 L=300032
43,7Steel, S3551PL 16 x 350 x 2504314,1Steel, S3551PL 22 x 125 x 8012488,3 1Padeye4532,2 1VISO clamp Tandemloc46
2,9Steel, Mild AS 2465 - 3/4 x 2 UNC16714,6Steel, S3551PL 20 x 155 x 15548
Drawing no.:
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This document is the property of DeepOcean and shall not be reproduced, copied, disclosed or used in any manner without written permission of DeepOcean.
Lifting Frame
HVL
Bachelor
NO.ENG.DR.18.005 Lifting Frame
USE - Issued for USE
Approved by:Checked by:Drawn by:
Rev.:
ADate:
27.04.201826.04.201825.04.2018
Anders VikebøØrjan GloppenNils Olav Hauge
Projection:
Status:
1 of 7
Gen. Tol. -NS-ISO 2768 U.S.O.: m
Gen. Welding -Tol. NS-EN ISO 13920 U.S.O.: B
Gen. Machined surface -roughness U.S.O.: 6,3
1
713
3500
6500
Total weight: 3249,2 kg
100 % MPI100 % UT1 Coat Primer 1 Coat Paint No SystemRAL1003To be punctured
5
6
4
2
3
7 (TYP) (TYP)
3125489 1000
(TYP)(TYP)
60°
71,0
3
71,03
8
4