GUIDELINES FOR MARINE LIFTING & LOWERING OPERATIONS 0027/ND Rev 11 Page 45 of 84 13 FABRICATION YARD LIFTS 13.1 INTRODUCTION 13.1.1
This section is applicable to lifts and other crane assisted operations (e.g. jacket roll-up operations) in
connection with erection and assembly. It also applies to load-out and load-in operations by onshore
cranes.
13.1.2
Relevant requirements in Sections 4 to 12apply for major yard lifts, roll-up operations and load out /
load in operations by lifting. The following sections describe exemptions and additional requirements
for such operations.
13.2 WEIGHT AND COG 13.2.1
The weight of a yard lifted item is often based on calculation only. In such cases, a minimum weight
contingency factor of 1.1 should be used to define the design weight.
13.2.2
The effect of extreme positions of the CoG should be evaluated for the design of the structure,
supports and lifting system.
13.3 ADDITIONAL LOADS 13.3.1
For roll-up operations, additional loads may be of significant importance and should be thoroughly
evaluated. Additional loads for roll-up would typically include the following
a)
winch/tugger line loads
b)
support reaction loads (vertical and horizontal)
c)
friction loads (at supports and slings)
d)
wind loads
e)
settlement of supports
13.3.2
Fabrication yard lifts may involve three or more cranes. Extreme crane loads, i.e. worst possible load
distributions within the cranes, should be calculated considering, at least, the following:
a)
support lay-out defined by the cranes
b) flexibility of the lifted object
c) crane types
d) limiting environmental conditions
e) lifting procedure
f) monitoring system/tolerances
A sensitivity analysis considering possible crane load variations should be considered.
13.3.3
The design of the lifted structure and lifting equipment should in some cases be based on the crane
extreme load capacity, e.g. overturning load for crawler crane. This is particularly relevant for lifting
with several highly utilised crawler cranes in a statically indeterminate arrangement where exact crane
loads may be difficult to control.
13.3.4
For operations involving multiple cranes, the maximum out of plumb of the hoist lines should be
defined/calculated and considered in the calculations.
13.3.5
The effect of swinging of the lifted object due to travelling crane movements should be evaluated.
13.3.6
The design of lifting equipment should in some cases be based on the crane extreme load capacity,
e.g. overturning load for crawler crane. This is particularly relevant for lifting with several highly utilised
crawler cranes, where exact crane load may be difficult to control.
