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DNV Marine Operations Rulesfor Subsea Lifting

New Simplified Method for Prediction of Hydrodynamic Forces

Tormod BeDNV Marine Operations

27th November 2007

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DNV Marine Operations' Rules for Subsea Lifting Slide 227 November 2007

Content

Brief overview of relevant DNV

publications

DNV Rules for Marine Operations, 1996,

Lifting Capacity Checks

New Simplified Method for calculation of

hydrodynamic forces

CFD Analyses Test Cases

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DNV Marine Operations' Rules for Subsea Lifting Slide 327 November 2007

Relevant DNV Publications

Lifting- and subsea operations :

DNV-OS-E402

Offshore

Standard forDiving Systems

January 2004

DNV Rules for Planning and Execution of

Marine Operations 1996

Special planned, non-routine operations of

limited durations, at sea. Marine operations arenormally related to temporary phases as e.g.

load transfer, transportation and installation. DNV Rules for Certi ficationof Lifting Appliances 2007(reprint of 1994 issue)

DNV Standard for Certi fication

No. 2.7-1 OffshoreContainers April 2006

Special planned non-routine operations Routine operations

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4/47DNV Marine Operations' Rules for Subsea Lifting Slide 427 November 2007

Relevant DNV Publications - Other

DNV-RP-C205 Environmental Conditions

and Environmental LoadsApril 2007(replacing Classification Notes No 30.5)

DNV-RP-H101 Risk Management in Marine

and Subsea Operations, January 2003

DNV-RP-H102 Marine Operations duringRemoval of Offshore Installations, April

2004

Standard for Certification No. 2.7-3

Portable Offshore Units, June 2006(a new revision is planned issued in 2008 which willinclude subsea units)

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DNV Marine Operations' Rules for Subsea Lifting Slide 527 November 2007

Relevant DNV Publications - Purchase

DNV publications can be purchased at:

http://webshop.dnv.com/global/

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DNV Marine Operations' Rules for Subsea Lifting Slide 627 November 2007

Content

Brief overview of relevant DNV

publications

DNV Rules for Marine Operations, 1996,

Lifting Capacity Checks

New Simplified Method for calculation of

hydrodynamic forces

CFD Analyses Test Cases

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DNV Marine Operations' Rules for Subsea Lifting Slide 727 November 2007

Capacity Checks - DNV 1996 Rules

Rules for Planning and Execution of Marine Operations, 1996

Part 1 - General

Pt.1 Ch.1 - Warranty Surveys

Pt.1 Ch.2 - Planning of

Operations

Pt.1 Ch.3 - Design Loads

Pt.1 Ch.4 - Structural Design

Part 2 - Operation Specif ic Requirements

Pt.2 Ch.1 - Load Transfer Operations

Pt.2 Ch.2 - Towing

Pt.2 Ch.3 - Special Sea Transports

Pt.2 Ch.4 - Offshore Installation

Pt.2 Ch.5 - Lifting

Pt.2 Ch.6 - Sub Sea Operations

Pt.2 Ch.7 - Transit and Positioning

of Mobile Offshore Units

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DNV Marine Operations' Rules for Subsea Lifting Slide 827 November 2007

Capacity Checks - DNV 1996 Rules

Part 2 Chapter 5

Dynamic loads, lift in air

Crane capacity

Rigging capacity,(slings, shackles, etc.)

Structural steel capacity(lifted object, lifting points,spreader bars, etc.)

Part 2 Chapter 6

Dynamic loads, subsea lifts

(capacity checks as in Chapter 5 applying dynamic loads from Chapter 6)

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DNV Marine Operations' Rules for Subsea Lifting Slide 927 November 2007

Capacity Checks DAF for Lift in Air

Dynamic loads are accounted for by

using a DynamicAmplification Factor

(DAF).

DAF in air may be caused by e.g.

variation in hoisting speeds or motions

of crane vessel and lifted object.

The given table is applicable foroffshore lift in air in minor sea states,

typically Hs < 2-2.5m.

DAF must be estimated separately for

lifts in air at higher seastates and for

subsea lifts !

Table 2.1 Pt.2 Ch.5 Sec.2.2.4.4

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DNV Marine Operations' Rules for Subsea Lifting Slide 1027 November 2007

Capacity Checks - Crane Capacity

The dynamic hook load, DHL, isgiven by:

DHL = DAF*(W+Wrig) + F(SPL)

ref. Pt.2 Ch.5 Sec.2.4.2.1

W is the weight of the structure,including a weight inaccuracy factor

The DHL should be checked againstavailable crane capacity

The crane capacity decrease whenthe lifting radius increase.

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DNV Marine Operations' Rules for Subsea Lifting Slide 1127 November 2007

Capacity Checks - Sling Loads

The maximum dynamic sling load, Fsling,can be calculated by:

Fsling= DHLSKLkCoGDW/ sin

ref. Pt.2 Ch.5 Sec.2.4.2.3-6

where:

SKL = Skew load factor extra loadingcaused by equipment and fabrication tolerances.

kCoG = CoG factor inaccuracies in estimated

position of centre of gravity.

DW= vertical weight distribution e.g.DWA = (8/15)(7/13) in sling A.

= sling angle from the horizontal plane.

Example :

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DNV Marine Operations' Rules for Subsea Lifting Slide 1227 November 2007

Capacity Checks - Slings and Shackles

The sling capacity Minimum breaking load,MBL, is checked by:

The safety factor is minimum sf3.0.(Pt.2 Ch.5 Sec.3.1.2)

sf

slingsling

MBL

F