Petroleum and natural gas industries - Specific requirements for offshore structures - Part 6: Marine operations
1 Scope
This document provides requirements and guidance for the planning and engineering of marine operations, encompassing the design and analysis of the components, systems, equipment and procedures required to perform marine operations, as well as the methods or procedures developed to carry them out safely.
This document is applicable to marine operations for offshore structures including
——steel and concrete gravity base structures (GBS);
——piled steel structures and compliant towers;
——tension leg platforms (TLP);
——deep draught floaters (DDF), including spars or deep draught caisson vessels (DDCV);
——floating production semi-submersibles (FPSS);
——floating production, storage and offloading vessels (FPSO);
——other types of floating production systems (FPS);
——mobile offshore units (MOU);
——topsides and components of any of the above;
——subsea templates and similar structures;
——gravity, piled, drag embedded and suction or other anchors;
——tendon foundations;
——associated mooring systems.
This document is also applicable to modifications of existing structures, e.g. installation of additional topsides modules.
This document is not applicable to the following marine operations:
a) construction activities, e.g. in a fabrication yard onshore, where there is no exposure to the marine environment;
b) drilling, processing and petrochemical activities;
c) routine marine activities during the service life of the structure;
d) drilling from mobile offshore drilling units (MODU);
e) installation of pipelines, flowlines, risers and umbilicals;
f) diving.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 15544
Petroleum and natural gas industries - Offshore production installations - Requirements and guidelines for emergency response
ISO 17776 Petroleum and natural gas industries - Offshore production installations - Guidelines on tools and techniques for hazard identification and risk assessment
GB/T 23511-2009 Petroleum and natural gas industries - General requirements for offshore structures
ISO 19901-1:2005 Petroleum and natural gas industries - Specific requirements for offshore structures - Part 1: Metocean design and operating considerations
ISO 19901-4:2003 Petroleum and natural gas industries - Specific requirements for offshore structures - Part 4: Geotechnical and foundation design considerations
ISO 19901-7:2005 Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
IMCA M 179 Guidance on the Use of Cable Laid Slings and Grommets. The International Marine Contractors Association
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 19900, ISO 19901-1, ISO 19901-4, ISO 19901-7 and ISO 19904-1 and the following apply.
3.1
action
external load applied to the structure (direct action) or an imposed deformation or acceleration (indirect action)
Example: An imposed deformation can be caused by fabrication tolerances, settlement, temperature change or moisture variation.
Note:: An earthquake typically generates imposed accelerations.
[GB/T 23511-2009, 2.1]
3.2
action effect
effect of actions on structural components
Example: Internal forces, moments, stresses, strains, rigid body motions or elastic deformations.
[GB/T 35989.1-2018, 3.5]
3.3
air cushion
air pumped into underbase compartments of the structure
Note: Normally applied in order to reduce the draught and increase the freeboard and/or to alter the structural loading.
[ISO 19903:2006, 3.10]
3.4
assembly
designed and fabricated group of bulk and equipment items that form one unit
[ISO 19901-5:2003, 3.1.1]
3.5
ballast
variable solid or fluid content in order to change the draught, stability, trim and/or heel of a structure afloat
Note: Adapted from ISO 19901-5:2003, 3.1.2.
3.6
ballast system
system used to change the draught, stability, trim and/or heel of a structure afloat
3.7
barge
simple floating vessel, normally non-propelled, on which a structure is transported
3.8
basic variable
one of a specified set of variables representing physical quantities that characterize actions, environmental influences, geometrical quantities or material properties, including soil properties
[GB/T 23511-2009, 2.5]
3.9
bending efficiency factor
factor by which the calculated breaking strength of a rope is reduced to take account of the reduction in strength caused by bending around a shackle, trunnion, padear or crane hook
3.10
bollard pull
towing or manoeuvring action that can be generated by a tug for an indefinite period of time with its propulsion system running at operational, as opposed to maximum revolutions per minute
Note: Bollard pull is expressed in kilonewtons.
3.11
bridging document
document that aligns and co-ordinates the requirements and responses of various parties in relation to a specific aspect of a project
Note: Commonly used to align and co-ordinate the emergency response procedures for owner and contractors.
3.12
bumper
temporary structure designed to protect structures or modules during the initial fitting stage of an installation operation
3.13
characteristic value
value assigned to a basic variable associated with a prescribed probability of not being violated by unfavourable values during some reference period
Note: The characteristic value is the main representative value. In some design situations, a variable can have two characteristic values, an upper and a lower value.
[GB/T 23511-2009, 2.7]
3.14
CoG envelope
defined constraint volume within which the centre of gravity (CoG) of an assembly or a module shall remain
3.15
consequence factor
factor applied to critical structural components in the design of lifting operations to ensure that these components have an increased factor of safety in relation to the consequence of their failure
Note: Consequence factors are additional safety factors, applied to critical structural components of the lifted object over and above the normal safety factors used in a WSD analysis of the lifted object. They are, accordingly, applied to lift points, their attachments to the object and components in the object supporting lift points. They are not intended for
application to slings, grommets and shackles.
3.16
construction afloat
addition of material or outfitting to the structure while afloat
Note: Adapted from ISO 19903:2006, 3.17.
