Staalbouwdag 2013 – Offshore Seminar T&I of Offshore Structures

Ir. J.P. Breedeveld

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T&I of Offshore Structures

Staalbouwdag 2013 – Offshore Seminar

Seaway Heavy Lifting – Installation Contractor’s Perspective

Offshore…?

Transportation – Steel design and fabrication

Installation – Steel design and fabrication

Offshore installation…our core business

SHL installation equipment

2,500 Mt revolving capacity

Length 183 m / Breadth 36 m / 140 pob

2,500 m2 deck space

5.5 m minimum draught

Anchors

5,000 Mt revolving capacity

Length 183 m / Breadth 47 m / 220 pob

4,000 m2 deck space

8.5 m minimum draught

Anchors and DP 3

Stanislav Yudin Oleg Strashnov

4

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Transportation

Fabrication

Shipbuilding vs Structural Design

Steel quality

Loadings

Motions

Wind

Barge deflections ?

Fatigue

Design considerations

Load out methods

Barge layout

Barge strength

Barge furniture

SAFETY (safe access)

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The World Offshore

... consequences for offshore platforms ...

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The World Offshore

extreme design conditions ....

Seastate Hs= 2.2 m

Tuesday 18 sept. 2012

15.00 GMT

Dynamics

onshore offshore

Lifted Loadout

Use of (multiple) floating or mobile cranes

Set-down on cargo barge

Grillage design ‘simple’

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Trailered Loadout

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Use of multiple trailer lines

Barge strength

Barge ballasting

Tidal restrictions during operation

Grillage design with lots of constraints

Cargo barge

October 2013

Qatar - Barzan Field

Structures fabricated in Korea (Hyundai)

All topsides ~3000t

Being installed by HLV Oleg Strashnov

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Transportation - fatigue

Crack…..

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Cargo barge – Typical North Sea

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Cargo barge

Delivery of structures by the fabricator (seafastened)

Barge furniture re-instated as per Class en Installation Contractor requirements

Barge prepared by fabricator for sail away; acceptance by MWS and Installation Contractor

Barge cleaned of loose items

Ballasted and tanks closed

Safe access to the barge (ladders) and seafastening (scaffolding) provided including handrailing

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Cargo barge

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Cargo barge

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Seafastening

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Seafastening removal

Pre-rigged ?

Safe ?

Best solution ?

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Seafastening removal

Moving barge

Working at height

“Dark and wet”

Limited work space

Back-up plan if this doesn’t work

It is easy to design this type of seafastening…….

It is very cumbersome to work with it offshore and causes safety issues!!!

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Seafastening removal

Braces

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Seafastening removal

Braces

Seafastening removed

Routing of hoses

Design of jacket systems

Outfitting on yard

Only small fabrication but can have a large impact on the successful completion of the project……

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Transportation Analysis

Wind energy sector

New designs

“New” installation methods

Discussions:-

- Barge strength

- Barge class requirements

- Transportation seastate

- Analysis methods (everything in one model)

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Transportation Analysis

FEM analysis of barge, grillage and structure

Load cases for barge deflections (hogging, sagging), weight variations and internal tank pressures

Load cases for design seastates

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Installation

Fabrication

Lifting Appliance certification

Steel quality

Welding procedures

Loadings:

Dynamics

Weight contingencies

Load distribution

Design considerations

Lifting height (clearance to crane)

Interference with equipment

SAFETY (safe access)

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Spreader Frame

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Spreader Frame

Weight of frame (100 – 200 t)

Weight of rigging on top (3% of lift weight)

Supported during transportation

Safe access to personnel on top

Protection of equipment during lifting and removal of rigging system

Removal of support structure (in between equipment….)

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Spreader Frame

Designed as lifting appliance (Lloyds, DNV, GL)

Certification requirements:-

Design appraisal

Material certification and traceability

Welding procedures (qualification)

Test loading…..?

Designed for single use?

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Spreader Bar

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Spreader Bar

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Spreader Bar

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Padeyes

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Padeyes

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Trunnion

How to keep the sling on?

How to get the sling off?

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Trunnion

Slings

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Steel Sling

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Rigging laydown

Rigging laydown and equipment protection

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Fibre Rope Slings

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T&I - Trends

From practical approach to scientific approach

What is design safety

What is failure

Academic “solutions”

“Guidelines” are “Rules”

Safety is to be a key driver for the design of permanent and temporary structures

More advanced design and calculation tools

FEM

Simulation

Use of high strength steel

Fy 460-690 N/mm2

Lifting appliances

Seafastening

Use of fibre rope technology

Lifting slings

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Steel – and what is left after 25 years…..

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