16 Cranes in a marine environment
In-shore and off-shore,
operating cranes from a
vessel or barge gives
additional dynamics to
the operation. Learn the
differences and
understand how to
access and deal with
these differences.
May 20, 2021
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Module Summary
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Juliana Bridge, Alphen aan den Rijn, August 2015
Juliana Bridge, The lift plan step 1
Juliana Bridge, The lift plan step 2
Juliana Bridge, how it was executed.
Juliana Bridge, conclusions from the Dutch Safety
Board
Differences between land and marine and
offshore cranes.
Dynamic Amplification Factors (DAF) in air
DAF in water lifting through the splash zone
Lifting through the splash zone
Lifting through the splash zone, slamming.
Lifting through the splash zone; varying buoyancy
Lifting through the splash zone; inertia force
Lifting through the splash zone; drag and friction.
Lifting through the splash zone
Lifting through the splash zone; what method to
use?
Do we need a lift plan?
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– Lifting of personnel.
– Lifting of personnel
– LOLER lifting operations and lifting equipment
regulations
– IMCA Guidelines for Lifting Operation
– Equipment Selection
– Possible safety measures to be considered
– Degrading lifting curves
– Down graded lifting curves depending on Hs
– Barge limitations:
– Local deck strength
– Environmental limitations
– Limitations on the workability:
– Risk assessment (1)
– Risk assessment (2)
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Juliana Bridge, Alphen aan den Rijn, August 2015
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Juliana Bridge, The lift plan step 1
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Juliana Bridge, The lift plan step 2
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Juliana Bridge, how it was executed.
What can we note already:
– Weight is 182 mT but CoG location not indicated.
– No stability calculations made for barges although it was even mentioned in the risk assessment.
– It is not mentioned how to rotate the bridge deck.
– Only one revision of project execution plan which is final and for information at the same time
Execution of the operation
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Juliana Bridge, conclusions from the Dutch Safety Board
Our own calculations showed that stability was to small to work with but did not show that the system
would capsize so why does the Dutch Safety Board concludes that “even when the lifting calculations
had been carried out faultlessly, an accident could not have been avoided.” The flexibility of the crane
has a negative impact to the stability of the barge.
You CAN NOT compensate for heel by ballasting when GM is close to 0m
The flexibility of the telescopic crane boom works a spring that controls the cog of the cargo. As a result,
the CoG of the cargo does
not appear at the top of the
Effect on cargo shift when secured by
crane but higher.
springs
In this case it was about
12m resulting in a GM
reduction of 1m
Rigid constrained load
Blue rigid crane
Red flexible crane
h = imaginary extra boom length.
Spring constrained load
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Differences between land and marine and offshore cranes.
While verticality is very important for land cranes,
marine and offshore cranes are designed for lateral
loads and working in a dynamic environment.
We distinguish:
1. marine cranes,
2. offshore cranes and
3. land cranes operated from a barge or vessel.
Marine cranes are the ‘standard’ cranes on board
vessel for which a heel of 5° and a trim of 2° are
assumed.
Offshore crane are unique and almost every new
build crane is a one-off.
The functional requirement and limits are given by
the crane supplier and agreed in cooperation with
the user.
2x7000 mT offshore crane
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Crawler crane on a barge
Derrick boom
Telescopic boom Marine crane
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Jack-up barge creates a static
base for the crane
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Dynamic Amplification Factors (DAF) in air
A mayor difference between onshore lifting is that we now have an operation
from a fixed environment to a moving environment or vice versa. Also from
one moving environment to another moving environment is possible.
The movements of the vessel(s) or barge(s) amplifies the forces acting on the
load. The DAF can be expressed as:
dynamic load + static load
DAF =
static load
The dynamic load is a load is subject to additional dynamic forces such as: in
water and going through the splash zone. These loads are affected by the
shape, size, weight, contents, vessel motions etc.
The DAF should for major offshore lifts be established on the basis of a
dynamic analysis, considering the effects in.
DNV-GL considers as minimum factors for lifts:
Going through the splash
zone
SHL (Static Hook
Load)
ONSHORE
From Quay to
barge/ship.
INSHORE
From crane vessel to barge/ship in
sheltered waters
OFFSHORE
from barge/ship
to a fixed platform
3 – 100 t
1.10
1.07+0.05 100/SHL
1+0.25 100/SHL
100 - 300 t
1.05
1.12
1.25
300 - 1000 t
1.05
1.10
1.20
1000 - 2500 t
1.03
1.08
1.15
1.03
1.05
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1.10
> 2500 t
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DAF in water lifting through the splash zone
A typical subsea lift consists of the following main
phases:
In air, lift off from deck and maneuvering an object
clear of transportation vessel and then,
1. lowering through the wave zone,
2. further lowering down to sea bed and
3. positioning and landing.
All phases of a subsea lift operation should be
evaluated.
For lifting in water we
can find a simplified
method in DNVGL-RPN103 “Modelling and
Analysis of Marine
Operations”
Both Simplified Methods
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Fline
W0
FB
Fc
FI
Fwd
Fd
Fw
Fs
Fe
=
=
=
=
=
=
=
=
=
=
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force in hoisting line/cable
weight of object (in air)
buoyancy force
steady force due to current
inertia force
wave damping force
drag force
wave excitation force
slamming force
water exit force.
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Lifting through the splash zone
The various phases when lifting through the splash zone. DAF
to be <2 to ensure force > 0 and avoid slack wires.
Force
Dynamic force
Submerged Weight
Weight in air
Time
0
Structure in air
(vessel motions)
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Structure touches
water (vessel
motions and
slamming)
Structure almost
submerged (vessel
motions, slamming
and drag)
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Structure fully
submerged (vessel
motions and drag)
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Lifting through the splash zone, slamming.
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Lifting through the splash zone; varying buoyancy
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Lifting through the splash zone; inertia force
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Lifting through the splash zone; drag and friction.
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Lifting through the splash zone
The resulting force
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Lifting through the splash zone
The required input
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Lifting through the splash zone
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Lifting through the splash zone
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Lifting through the splash zone
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Lifting through the splash zone; what method to use?
Loads depend on:
– vessel motions,
– location of crane tip,
– wave pattern,
– object weight in air,
– object weight in water,
– object geometry and
– object orientation.
Simple
Generic lifts: Covered by vessel TRA
(ROV basket, Gabion bags, concrete
mattresses etc.)
Small structures: Generally analyzed in
Macsi or similar
(Protection covers, SLP, small PLEMS, PLETS
etc.)
Intermediate size structures: Analyzed in
OrcaFlex or by the simplified method
(PLEMS, PLETS, Riser Bases, Satellites etc.)
Large / Complex / difficult structure CFD.
(Foundations, templates, manifolds etc.)
Complex
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Do we need a lift plan?
Yes, any lift offshore needs to be planned. A lifting operation involves storing and releasing
energy and always contains risks. By planning the lift, we can:
– Ensure that the risk are assessed, controlled and if possible eliminated.
– Give time to consider how?
– Find suitable equipment and competent persons
– Get responsibilities clear
– Evaluate interference with other operations
(SIMOPS)
Tugger lines are
used to control
the hoist.
For big hoists, the
tugger lines are
on the winch
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Lifting of personnel.
Personnel Rated Loads (API Spec 2C / USA
law)
– All hooks used for support of personnel shall
have an operable latch to prevent the
personnel basket sling from coming off the
hook accidentally.
– The rated load when handling personnel
shall be the least of 1/3 of the calculated
SWL for non-personnel load rating
Billy Pugh
– The design factor of load hoist wire rope
when handling personnel shall not be less
than 10.
LOLER
– Clutches or other means of disengaging the
drive train are prohibited for personnellifting operations.
– during transfer over the sea, passengers are
provided with survival suits and life jackets of
an approved type.
Crew Basket training is supplied in addition to
BOSIET/FOET or HUET
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Billy Pugh
Frog
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Lifting of personnel
q
q
q
q
q
q
q
q
q
q
q
q
Prevention of person(s) becoming stuck/trapped
Prevention of person(s) falling/being crushed
Communications between passengers/operator
Suitability of equipment and accessories
Environmental hazards
Correct PPE/harnesses/etc.
Trained/competent personnel
Certification/pre-use checks
Vessel-/site-specific procedures
Equipment secured in transporter
Efficient means of rescue
Limiting conditions of use
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LOLER lifting operations and lifting equipment regulations
LOLER is legislation and most
be adhered to within its
jurisdiction.
LOLER applies to all:
– Locations covered by the
Health and Safety at Work
Act
– Offshore installations
within UK territorial waters
and the UKCS (United
Kingdom Continental Shelf
Source: www.dbd-data.co.uk
I Applies to the following:
– Any employer whose personnel are
employed to use lifting equipment
– Self-employed personnel using own or
other company's lifting equipment
IACS; the International Association of Classification Societies
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IMCA Guidelines for Lifting Operation
IMCA is an international association with around 1,000 members operating in over
60 countries. The value proposition is to influence our industry in key technical,
contractual, policy and regulatory matters that are in the best interest of the marine
contracting industry.
International
Marine
Contractors
Association
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Equipment Selection
•Select equipment that is fit for purpose
•Equipment must be certified and have operating instructions
•Factors to considered
•Purpose(s) of use,
•Technical specification and operating parameters,
•Location of use, environmental and ergonomic factors,
•competency of personnel using equipment,
•Approved Safe use and operating instructions,
•Maintenance, Test and Inspection Recommendations,
•Stability, installation and dismantling of equipment,
•…
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Possible safety measures to be considered
A check list can be part of the lifting plan. Below an example to be completed by the competent
person
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
Weight not verified
q
Stability of load
q
High centre of gravity
q
Awkward size/shape/sharp edges q
No dedicated lift points
q
No certified suspension points for
lifting equipment
q
Packing protection load/lifting
q
equipment/assets
Loose objects removed from load q
Load on pallet requires securing q
Tag lines required
q
Buoyancy of objects
Lifting of chemicals
q
Access and egress for slinging
No lift point directly above load q
Accessories/equipment fit for
q
purpose/SWL
q
Lifting equipment/accessories
q
certificates
Stability of lifting equipment
q
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Pre-use equipment checks
Crane mode verified
q
Vessel stability
q
Vessel ballasting required
q
Lifting over
plant/equipment/assets
q
Restricted head room
q
Lay-down area
size/strength/stability
q
Route and lay-down area clear
q
Route and lay-down area
obstructed
q
Lay-down in operational radius of q
lifting equipment
q
Conflicting operations
q
Cultural, communication,
q
language issues
Diving operations – precautions
Emergency/rescue plans
Environment: visibility/wind
speed/wave height/tide
Sudden changes in environmental
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conditions
Load visibility during night/subsea
working
Blind lifting
Lighting pick-up and set-down
areas
Dynamic factors involved
Seabed suction
Seabed conditions
Competent and sufficient
personnel
Suitable adequate supervision
Correct PPE
Toolbox talk required
Sea fastenings removed
Pre-use equipment check
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Degrading lifting curves
Crane curves for onshore
can not be used.
‘Standard’ crane curves
assume that the crane is
on a fixed non-moving
surface.
Offshore and marine
cranes are designed to
withstand the vessel
dynamics. This means that
for offshore use, crane
curves are degraded or
cranes are considered not
suitable at all for offshore
use.
Cranes have multiple crane
curves depending on the
environmental conditions.
Telescopic land cranes are
not suitable for use in a
dynamic environment.
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Down graded lifting curves depending on Hs
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Barge limitations:
Free floating
– intact stability condition
– Sailing condition (boom down)
– Lifting condition (boom up with load in the hook)
• Stability range
• Wind overturning moment
• GM value
• static heel due to wind
• Static heel due to load
• Crane limitations (heel max 3 deg)
Jack-up:
– Maximum leg loads during crane movements of any kind
– Soil conditions
Spud Leg Barges
– maximum leg loads during crane movements of any kind,
– dynamic leg loads due to waves and wind
Structural strength
– Local
– Global
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JB-117 Self
Elevating
Platform
Lastdrager 6 with Mammoet
crane
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Local deck strength
Check for allowable deck load. The use
of heavy steel / hard wood load
spreading mats is recommended to
create a proper load spreading.
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Environmental limitations
Closely monitor the
environmental conditions in the
harbour, sheltered area or
offshore
Tidal range and currents,
especially important for column
stabilized barges.
Water depth, especially
important for spud pole barges
and jack-up barges
Soil condition to be verified for
column stabilized barges and
jack-up barges
Reliable weather forecasting
– Wind data
– Wave height and period
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Limitations on the workability:
Efficient communication
between parties involved
Efficient monitoring tools
Operations to be planned and
split up in workable steps.
Coordinate with other ongoing
operations. SIMPOPS
All steps should have a fall back
scenario
Operations to be executed in
workable environmental
conditions
Working on water involves
additional measures regarding
safety
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Risk assessment (1)
A risk assessment matrix like shown below can be used with the job risk assessment.
(Potential costs of loss shown could vary dependent on company and operations)
5
Moderate Injury leading to a lost time
accident or persistent
dermatitis or acne
Slight
Minor injury requiring first
aid treatment or headache,
nausea, dizziness, mild
rashes
Negligible Negligible injury or health
implications, no absence
from work
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presents limited harm to the
environment
and requires minor corrective action
>$10,000
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A
B
C
D
E
very
unlikely
4
Serious injury, poisoning,
sensitisation or dangerous
infection
potentially harms or adversely affects
>$1m
the general public and has the
potential for widespread concern
regarding the company’s operations.
Can have a serious economic liability
on the business
potentially harms or adversely affects >$250,000
employees and the environment at
the worksite. Requires specialist
expertise or resources for correction
potentially harms or adversely affects >$50,000
employees and the environment at
the worksite. Requires general
expertise or resources for correction
presents limited harm to the
>$10,000
environment and requires general
expertise or resources for correction
Probability rating
unlikely
3
High
Cost of
loss
possible
2
Very high Fatality(s), terminal lung
disease or permanent
debility
Environmental
(any incident that ...)
likely
1
Actual/potential
consequences
Personal illness/injury
very
likely
Hazard Descriptive
severity
words
category
1
1
1
2
3
1
1
2
2
3
1
2
2
3
3
2
2
3
3
3
2
3
3
3
3
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Risk assessment (2)
There are various moments to identify risks.
HIRA
Hazard identification and risk assessment
JRA
Job Risk Assessment
TRA
Task Risk Assessment
naming depends on the company.
JSA
Job Safety Analysis
In addition, there is the Equipment Risk Assessment which is part of the JRA.
Keywords to help with the
equipment risk assessment are
q Is the equipment designed for
this type of lift?
q Have any modifications been
made to the equipment?
q Could alarm settings require
attention, e.g. if changes have
been made to wire rope length
on drums?
q strength and stability of lifting
equipment, rigging and load;
q ergonomic considerations;
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q operator protection;
q environmental conditions;
q location/proximity/environment
al hazards;
q the nature of the anticipated
load(s) (e.g. hazardous or
dangerous substances);
q whether it involves lifting of
persons;
q means of attaching/detaching
and securing loads;
q loading and set-down
arrangements;
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q access and egress arrangements,
particularly in emergency situ
q overturning and overloading;
q other emergency situations;
q maintenance and inspection
requirements whilst in use;
q dismantling and storage
requirements;
q transportation methods for
continued integrity.
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