Offshore_Access_Gangways_Guide_e.pdf

Guide for Certification of

Offshore Access Gangways

August 2016

GUIDE FOR CERTIFICATION OF

OFFSHORE ACCESS GANGWAYS

AUGUST 2016

American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862

© 2016 American Bureau of Shipping. All rights reserved.

ABS Plaza 1701 City Plaza Drive Spring, TX 77389 USA

Foreword As the demand for a safe and efficient walk to work (W2W) approach prevails in the offshore oil and gas industry, it is envisaged that there will be a significant growth in the use of offshore access gangway systems for the manning and transfer of personnel to and from offshore facilities.

Noting the special design and operational characteristics of offshore access gangway systems, ABS has developed this Guide to provide provisions for the certification of offshore access gangway systems used for connecting two offshore units to transfer offshore personnel on a temporary basis. The requirements contained within this Guide included either via direct inclusion or a reference to other ABS Rules or Guides as well as relevant recognized international Regulations in existence prior to the issuance of this Guide.

This Guide references relevant international statutory Regulations and guidelines that are considered to be applicable. While it is the intent of the Guide to be consistent with these Regulations and guidelines, it is the ultimate responsibility of the users of this Guide to refer to the most recent text of those Regulations and guidelines.

This Guide is to be used in conjunction with other Rules published by ABS and the recognized international Regulations.

This Guide is for the use of designers, builders, owners and operators of offshore access gangway systems.

This Guide becomes effective on the first day of the month of publication.

Users are advised to check periodically on the ABS website www.eagle.org to verify that this version of this Guide is the most current.

We welcome your feedback. Comments or suggestions can be sent electronically by email to rsd@eagle.org.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 ii

CONTENTS

SECTION 1 Scope and Conditions of Certification 1 Application 3 Scope 5 Alternatives 7 Class Notations 9 Existing Offshore Access Gangway Systems 11 Approval under ABS Type Approval Program

11.1 Product Design Assessment

11.3 Type Approval Program

13 Other Regulations

13.1 International and Other Regulations

13.3 Governmental Regulations

15 Submission of Plans 17 Units

SECTION 2 General 1 Scope

1.1 Offshore Access Gangways

1.3 Category of Gangways

1.5 Types of Motion Compensation Systems

3 Submission of Plans and Design Data

3.1 General

3.3 Information to Be Submitted

5 Loading, Handling and Securing 7 Terms and Definitions

7.1 Accidental Situation

7.3 Allowable Stress Design (ASD)

7.5 Base Frame

7.7 Central Control Cabin

7.9 Computer-Based System

7.11 Design Service Temperature

GUIDE FOR CERTIFICATION OF

OFFSHORE ACCESS GANGWAYS

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 iii

7.13 Emergency Lift off Accumulator Package

7.15 Heave Motion Compensation System

7.17 Landing Structure

7.19 Landing Support Structure

7.21 Limit State

7.23 Luffing Cylinders

7.25 Motion Compensation System

7.27 Offshore Access Gangway Parking or Stowage

Arrangements

7.29 Offshore Access Gangway System

7.31 Pedestal and Foundations

7.33 Primary Structural Member or Critical Component

7.35 Slew Bearing Assembly (Swing Circle Assembly)

7.37 Telescopic Bridge

7.37 Telescopic Drive

7.41 Telescopic Main Bridge

9 Certification of Components

TABLE 1 Examples of Primary Structure TABLE 2 Examples of Critical Machinery Components TABLE 3 Offshore Access Gangway Components Certification(1)

FIGURE 1 Example Configuration of an Offshore Access Gangway

SECTION 3 Structural Requirements 1 General 3 Materials

3.1 Steel

3.3 Aluminum Alloys

3.5 Effective Corrosion Control

5 Design Loads and Conditions

5.1 Design Loads

5.3 Design Conditions

7 Strength Assessment

7.1 General

7.3 Allowable Stress Assessment Criteria for ULS and

ALS

7.5 Fatigue Assessment Criteria for FLS

7.7 Serviceability Limit State (SLS)

9 Landing Mechanism 11 Pedestals, Foundations, and Supporting Structures 13 Slewing Mechanism 15 Telescoping Mechanism 17 Wire Rope

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19 Loose Gear

TABLE 1 Design Loads Applied to the Design Conditions TABLE 2 Structural Strength Assessment TABLE 3 Allowable Stress Coefficients, Sc TABLE 4 Fatigue Design Factors

FIGURE 1 Type I Gangway - Distributed Live Loads FIGURE 2 Type I Gangway - Live Loads for Emergency Lift-off

Condition FIGURE 3 Type II Gangway - Live Load for Gangway Supported at

Two Ends FIGURE 4 Type II Gangway - Live Load for Uplift or Cantilever

Condition FIGURE 5 Type II Gangway - Live Load for Emergency Lift-off

Condition FIGURE 6 Relative Deflection

SECTION 4 Machinery and Systems 1 General 3 Materials 5 Electrical Systems 7 Piping Systems

7.1 Hydraulic Systems

9 Pressure Vessels 11 Rotating Machines 13 Computer-based Control Systems 15 Motion Compensation Systems 17 Low Temperature Operation 19 Hazardous Locations 21 Blocking Mechanism 23 Electronics and Communications 25 Emergency Recovery 27 Safety Systems and Arrangements

27.1 General

27.3 Monitoring Systems

27.5 Alarm System

27.7 Handrails and Grids

27.9 Slip Resistant Surface

27.11 Landing Area

27.13 Break-Away System

27.15 Fire Protection

27.17 Control Cabin Protection

29 Visual Aids

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 v

29.1 Markings

29.3 Lighting System

SECTION 5 Testing and Surveys 1 General 3 Surveys during Construction

3.1 General

3.3 Functionality Testing

5 Load Testing

5.1 Load Testing Procedures

5.3 Test Loads

7 Surveys during Installation 9 Surveys after Construction

9.1 Annual Survey

9.3 Retesting Survey

9.5 Repairs and Alterations

9.7 Reinstallation Survey

11 Slewing Ring Surveys 13 Inspection of Wire Rope 15 Monthly Inspection by Vessel’s Personnel

SECTION 6 Risk Assessment 1 Risk Assessment

SECTION 7 Register for the Offshore Access Gangways 1 General 3 Certificates and Forms 5 Owner’s Overhaul and Inspection Record 7 Repairs and Alterations 9 Addition of New Gear and Wire Rope

APPENDIX 1 References

APPENDIX 2 Samples of ABS Register of Offshore Access Gangways 1 American Bureau of Shipping Register of Offshore Access

Gangway

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 vi

S E C T I O N 1 Scope and Conditions of Certification

1 Application This Guide contains provisions for the certification of offshore access gangway systems installed aboard vessels, offshore floating units, and fixed offshore units.

If specifically requested by the Owner, and agreed by the Administration, this Guide may also be used as a basis for acceptance or certification under the requirements of Administrations. Owners who desire to have offshore access gangway systems evaluated for compliance with National Regulations should contact

ABS.

3 Scope This Guide provides requirements for certification of all offshore access gangway systems installed on a vessel or offshore floating unit, including, but not limited to the following routine gangway operations from:

● Vessel to vessel

● Vessel to offshore floating unit

● Offshore floating unit to vessel

● Offshore floating unit to offshore floating unit

● Vessel to fixed offshore unit

● Offshore floating unit to fixed offshore unit

The Guide applies to connected vessels or offshore floating units that maintain position by means of Dynamic Positioning System (DPS), mooring system or any sophisticated station keeping system, and offshore fixed units.

Gangways are to be designed and certified taking into consideration the vessel/unit where they will be installed. When the gangway is reinstalled to a new vessel/unit, either within the same field or in a different operating area, the strength of the gangway is to be reassessed to satisfy that the gangway will remain in compliance with applicable requirements in this Guide. The design reviews and surveys related to the reinstallation are to be completed in accordance with this Guide.

5 Alternatives The Committee is at all times ready to consider alternative arrangements and designs which can be shown, through either satisfactory service experience or a systematic analysis based on sound engineering principles, to meet the overall safety, serviceability, and strength standards of the applicable Rules and Guides.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 7

The Committee will consider special arrangements or designs of offshore access gangway systems and equipment which can be shown to comply with standards recognized in the country in which the gangway and its equipment are designed or built, provided these are not less effective than the requirements contained in this Guide.

7 Class Notations The Certification of Offshore Access Gangways is issued under the provisions of this Guide and follows the register procedure in Section 7. A vessel or unit classed by ABS, which has an ABS Register of Offshore Access Gangway Systems permanently installed, is to be distinguished by the class notation GRC(Type I or II, PS, or AS), as follows:

Type I signifies that the gangway system permits unrestricted flow of personnel transfer within the capacity limitation and is supported at both ends

Type II signifies that the gangway system permits limited flow of personnel transfer

PS signifies that the vessel or unit has an installed passive motion compensation gangway system designed, constructed, and tested in accordance with the respective requirements of this Guide

AS signifies that the vessel or unit has an installed active or full active motion compensation gangway system designed, constructed, and tested in accordance with the respective requirements of this Guide

For example, a vessel with an active motion compensation gangway system and the gangway allows personnel to transfer freely is to be assigned the notation GRC(Type I-AS). In the case of a vessel with more than one gangway, separate reviews and surveys for each gangway will be required, and multiple gangway systems are to be included in the notation.

9 Existing Offshore Access Gangway Systems For an existing offshore access gangway system, submission of information as required in the respective sections of this Guide, with verification of material, is required.

An existing gangway system may be certified subject to a satisfactory plan review, condition survey, operational tests (including luffing, slewing, telescoping), test of safety devices, and proof testing of the offshore access gangway systems as required in this Guide. The condition survey is to include inspection for excessive wear, damage, corrosion, and fractures. Nondestructive testing or verification of materials may be required at the discretion of the Surveyor. All mechanical, electrical, and piping systems and components are to be examined as deemed necessary by the attending Surveyor.

11 Approval under ABS Type Approval Program

11.1 Product Design Assessment

Upon application by the manufacturer, each model of a type of offshore access gangway is to be design assessed as described in this Guide. For this purpose, each design of an offshore access gangway type is to be approved in accordance with the requirements of this Guide. The type testing specified in 5/3 is to be conducted in accordance with an approved test schedule and is to be witnessed by a Surveyor. Offshore access gangways so approved may be applied to ABS for listing on the ABS website as Products Design Assessed. Once listed, and subject to renewal and updating of the certificate as required by 1-1-A3/5.7 of the ABS Rules for Conditions of Classification (Part 1), offshore access gangway particulars will not be required to be submitted to ABS each time the gangway is proposed for use on board a vessel.

11.3 Type Approval Program

Offshore access gangway types which have their design approved in accordance with 1/11.1 and the quality assurance system of their manufacturing facilities approved in accordance with 5/3.1.1 and 1-1-

Section 1 Scope and Conditions of Certification 1

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A3/5.5 or 1-1-A3/5.7 of the ABS Rules for Conditions of Classification (Part 1) will be deemed Type Approved and will be eligible for listing on the ABS website as Type Approved Product.

13 Other Regulations

13.1 International and Other Regulations

While this Guide covers the requirements for the certification of offshore access gangway system and their equipment, the attention of Owners, designers, and builders is directed to the regulations of international, governmental, and other authorities dealing with those requirements in addition to or over and above the classification requirements.

Where authorized by the Administration of a country signatory thereto and upon request of the Owners of a certified offshore access gangway system or one intended to be certified, ABS will survey for compliance with the provision of International and Governmental Conventions and Codes, as applicable.

13.3 Governmental Regulations

Where authorized by a government agency and upon request of the Owners of a new or existing offshore access gangway system, ABS will survey and certify a classed offshore access gangway system or one intended to be classed for compliance with particular regulations of that government on their behalf.

15 Submission of Plans Each Section of this Guide identifies a list of offshore access gangway system components that are required for the certification of the offshore access gangway system. In most cases, manufacturers’ components and system related drawings, calculations, and documentations are required to be submitted to substantiate the design of the system or component. In these cases, upon satisfactory completion of ABS review of the manufacturers’ submittals, ABS Engineers will issue a review letter. This letter, in conjunction with the submitted package, will be used and referenced during surveys and subsequently issued reports by attending ABS Surveyors.

Upon satisfactory completion of all of the required engineering and survey processes, ABS will issue the Certificate to the offshore access gangway system.

17 Units This Guide is written in three systems of units: SI units, MKS units and US customary units. Each system is to be used independently of any other system. Unless indicated otherwise, the format of presentation of the three systems of units in this Guide is as follows:

SI units (MKS units, US customary units)

Section 1 Scope and Conditions of Certification 1

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S E C T I O N 2 General

1 Scope This Guide provides requirements for the certification of offshore access gangway systems installed aboard vessels or floating/fixed offshore units.

This Guide covers the offshore access gangway, its foundation, and supporting structures (e.g., tower, pedestal, etc.). However, the supporting structure under the deck that is integrated into the vessel/unit hull is not within the scope of this Guide. ABS approval and certification of the offshore access gangway system to this Guide is limited to the reviewed conditions.

This Guide is applicable to offshore access gangways used for connecting two offshore units or vessels to transfer offshore personnel on a temporary basis. A gangway intended to operate at an inclination greater than 30 degrees is not within the scope of this Guide.

A gangway operated as a primary means of escape or installed where potential hazardous utility functions are attached is subject to special consideration in consultation with the Administration.

1.1 Offshore Access Gangways

In general, an offshore access gangway consists of various parts, which are primarily dependent on the level of motion compensation. Section 2, Figure 1 depicts one type of offshore access gangway that includes a non-extended part connected to the supporting structure and a telescopic part with a landing and connecting mechanism (e.g., landing device/cone).

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 10

FIGURE 1

Example Configuration of an Offshore Access Gangway

The supporting structure of the gangway may consist of a frame with heavy steel members, a base structure typically composed of thick welded plates, and a slewing ring. Typically the supporting structure is integrated into the vessel deck of the vessel/unit. An offshore access gangway includes associated mechanical, hydraulic, electrical, and safety systems as well as one or more control cabin/station.

Typically, an offshore access gangway rests in a parked position on a support “cradle” on the deck of the vessel/unit. When required, the gangway is lifted, slewed, and extended to the required landing position, typically using hydraulic mechanisms. In some cases, a motion compensation system is used to reduce the lift-off motions during connection or while connected. Once the landing cone arrives at the desired position on the adjacent offshore unit, it will be fastened to that unit. In some cases, the gangway landing end may be pushed in between horizontal constraints in the landing area without fastening or operated as a cantilever, the gangway normally provides a mechanism to keep a “form closed” connection. When connected, the telescopic part is free to slide within the non-extended part, with limits set for the maximum and minimum sliding positions.

If the operating limits are exceeded, an alarm is to sound and the gangway will be lifted manually during normal operation, or lifted automatically for emergency lift, and then retrieved and returned to the support cradle.

1.3 Category of Gangways

An offshore access gangway is to be categorized as one of the two types in the sections below.

1.3.1 Type I: Unrestricted Flow of Personnel Transfer

i) This type of gangway is to be used for unrestricted flow of personnel transfer between the connected units (i.e., an unlimited number of personnel may pass the gangway at any given time as long as the total load is within the gangway’s design load capacity).

ii) The gangway is supported at both ends in all three axis directions.

iii) The telescopic end of the gangway is to be capable of being readily retracted and moving to its stowed position safely within a short period of time when, for example, design conditions are expected to be exceeded.

Section 2 General 2

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1.3.2 Type II: Limited Flow of Personnel Transfer

i) This type of gangway is to be used for limited flow of personnel transfer between the connected units through manual or automatic flow control (i.e., only a specified number of personnel may be present on the gangway at any given time, based on the gangway design).

ii) The gangway is supported at least at one end in all three axis directions.

iii) The gangways are to be provided with the self-detach devices for the telescopic end and are to be capable of moving the gangway to its stowed position safely within a short period of time when, for example, design conditions are expected to be exceeded.

1.5 Types of Motion Compensation Systems

The following types of motion compensation systems are considered in this Guide.

1.5.1 Full Active Motion Compensation System

A system that all drive mechanisms present (slewing, luffing, telescoping) are actively controlled and compensates for all degrees of vessel motions on the gangway structure.

1.5.2 Active Motion Compensation System

A system that uses motion sensor signals in the control system and external energy to compensate for the effects of the vessel (or unit) motions on the offshore access gangway.

1.5.3 Passive Motion Compensation System

A system with integrated features that allow the gangway to maintain the relative motions between vessels (or units) does not make use of motion sensor signals or external systems in the control system.

3 Submission of Plans and Design Data

3.1 General

Plans showing the arrangements and details of the offshore access gangway system are to be submitted for review before fabrication begins. These plans are to clearly indicate the scantlings, materials, joint details, and welding. Plans should generally be submitted electronically to ABS; however, hard copies will also be accepted.

3.3 Information to Be Submitted

The following plans and supporting data are to be submitted for review and approval as applicable.

3.3.1 Offshore Access Gangway Structures

i) General arrangement, assembly plans, and description of operating procedures and design service temperature.

ii) Applicable design loads (i.e., dead, live, and dynamic loads) including details for gangway stiffness; environmental loads including the effects of wind, snow, and ice; loads caused by luffing, slewing, and telescoping operations; loads due to static list and/or trim of the vessel or unit; loads due to vessel or unit motions, etc.. Supporting calculations illustrating how the loads were derived are to be provided.

iii) Details and drawings of all primary structural members and offshore access gangway supporting structure (i.e., pedestal, foundation, etc.).

iv) Suitably referenced stress diagram, stress and fatigue analysis, and other supporting calculations. Where computer assisted analysis is used for the determination of scantlings, details of the software, describing input and output data, and procedures are to be included together with the basic design criteria.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 12

v) Material specifications.

vi) Welding details and plans indicating extent and location of nondestructive inspections of welds for gangway structure, pedestal, and foundation.

vii) Gangway pedestal and foundation drawings together with calculations indicating the maximum reactions and overturning moments.

viii) Wire rope specifications and applicable corresponding wire rope reeving diagram.

ix) Swing circle assembly drawing and details, including, as applicable:

● Hold down bolt size with calculations, arrangement of bolts, material, grades, and pretensioning, together with the method used for pretensioning.

● Slewing ring drawings, along with static strength calculations and details, which include material specifications of raceways and rollers or balls, hardness and heat treatment details of raceways and rollers, number and diameter of rollers or balls, raceway static capacity, specified planarity (flatness) tolerances and surface finish of bearing and supporting flanges, bearing wear tolerances.

● Procedure for wear down measurement of slewing ring (i.e., “rocking test”).

x) Documentation identifying proof load testing weights, locations, conditions, and procedures in accordance with 5/3.

xi) Documentation of gangway risk assessment (see Section 6).

xii) The following plans, together with supporting data and particulars, are to be submitted as applicable by the Owner:

● Escape and access route plan

● Fire control plan

● Emergency preparedness manual

3.3.2 Offshore Access Gangway Machinery, Piping and Electric Systems

i) Description and general details of safety devices and features, such as limit switches, auto brakes, monitoring and alarms, etc.

ii) Detailed diagrammatic plans of piping system accompanied by lists of materials giving size, wall thickness, maximum working pressure and material (including mechanical properties) of all pipes and the type, size, pressure rating and material of pumps, hoses, manifolds, valves, and fittings.

iii) Detailed diagrammatic plans of electric wiring systems including complete feeder lists, type of wire or cable, rating or setting of circuit breakers, rating of fuses and switches and interrupting capacity of circuit breakers and fuses.

iv) Documentation for computer based systems, as per 4-9-1/7 of the ABS Rules for Building and Classing Marine Vessels (Marine Vessel Rules).

v) Details of accumulators, heat exchangers and slewing, luffing, and telescoping hydraulic cylinders indicating shell, heads, pistons, piston rods, log attachments, tie rod dimensions, and threading details, as applicable with material specifications (including mechanical properties).

vi) Detailed diagrammatic plans of central control mechanism and motion compensation mechanism including control cabinets, motion sensors, hydraulic cylinders, reduction gears and coupling bolts, and foundation arrangements, as applicable.

vii) Design justification including component strength calculations, stress analysis, material specifications, weld procedure specifications, and the extent of nondestructive examination as considered necessary are to be submitted for items v. and vi. above.

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viii) Details or Manufacture’s Affidavits of all prime movers such as diesel engines, motors, and generators.

ix) List of the assembled loose gear specifying the Safe Working Load for each component.

x) A list/booklet identifying all equipment of the offshore access gangway in hazardous areas and the particulars of the equipment; including manufacturers’ names, model designations, rating (flammable gas group and temperature class), the method of protection (flammable proof, intrinsically safe, etc.), any restrictions in their use and document of certification.

xi) A declaration for absence of Asbestos in the manufacture or packaging of all materials, components, equipment, machinery, piping systems and electric installations.

xii) Details of emergency and emergency recovery operational procedures, including conditions, precautions, and limitations for personnel transfer.

xiii) Documentation of Failure Modes and Effect Analysis (FMEA), as per 4-9-1/7.3.9 of the Marine Vessel Rules.

3.3.3 Operating Manual

An operation and maintenance manual is to be submitted for review and is to include the following:

● The system information about operation conditions

● Operating instructions for normal and degraded operating modes, and operational, deployment/ retrieval procedures

● Step-by-step instructions for the use of the redundancy features

● Operational limitations, such as maximum number of persons on gangway, vessel/unit motion characteristics, wind speeds, geometrical limitations, etc., and the actions to be taken to limit gangway loads

● Safety and contingency procedures

● Maintenance requirements

● Periodic testing requirements

The critical limits are to be displayed in the control cabin as well as at the gangway ends.

3.3.4 Testing Procedure

The following are to be submitted to ABS for review:

● Load test procedures

● Factory acceptance test procedures

● On-board testing procedures

● Rocking test

References to applicable sections of pertinent recognized standards (such as ISO 7061, UK HSE OTO 2001-069, SOLAS II-1/3-9, IMO MSC.1/Circ. 1331, as appropriate to the testing procedure) are to be identified on the plans submitted for approval and in the accompanying documentation.

If the gangway supplier is employing a third party to supply the systems or components, then relevant specifications are to be reviewed by ABS before the submission of the third party documents for acceptance.

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5 Loading, Handling and Securing System certification is based on the understanding that responsibility rests with the Operator or Owner for control of offshore access gangway loads; offshore access gangway handling during slewing, lifting, and telescoping loads; avoidance of improper weight distributions while operating; securing of the gangway on the vessel or unit when not in use; maintenance of the offshore access gangway; and handling and stability of the vessel or unit during operation of the gangway; and the adequacy of the structure of the other vessel or unit on which the offshore access gangways lands.

7 Terms and Definitions

7.1 Accidental Situation

A situation involving an exceptional condition of the structure, mechanical, or electrical components. For example: impact, fire, explosion, loss of intended differential pressure, failure of critical components, etc.

7.3 Allowable Stress Design (ASD)

Allowable, or permissible, stress design is a design method in which the stresses that develop in structures or components under maximum design loads are verified against the prescribed maximum allowable stresses of the structure or component.

7.5 Base Frame

The base structure to which the offshore access gangway’s main bridge is attached.

7.7 Central Control Cabin

The main unit that controls the offshore access gangway’s electrical and mechanical systems and provides the gangway operating functions, and system monitoring, etc.

7.9 Computer-Based System

A system of one or more microprocessors, associated software, peripherals, and interfaces.

7.11 Design Service Temperature

The minimum anticipated temperature at which the gangway will be operated, as specified by the Owner, manufacturer, or builder.

7.13 Emergency Lift off Accumulator Package

The stored power/energy system for an emergency disconnect in case of a black out. It also can be replaced by (external) emergency power supply (e.g., from the vessel).

7.15 Heave Motion Compensation System

A system that is used to maintain the vertical motion of the gangway within operating limits. This includes passive or active heave motion compensation systems. A passive heave motion compensation system uses stored energy to maintain the vertical position of the gangway within the preset range. An active heave motion compensation system uses motion sensors and external energy to maintain the vertical position of the gangway at a predetermined location within a fixed frame of reference.

7.17 Landing Structure

A component used to facilitate landing support of the telescopic bridge onto the connected vessel or unit.

7.19 Landing Support Structure

The support structure that attaches the landing cone support onto the connected vessel or unit.

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7.21 Limit State

The point at which the structure or component has exceeded the allowable design criteria (e.g., strength, fatigue, survivability, deflection).

7.23 Luffing Cylinders

The hydraulic cylinders providing luffing movement of the gangway.

7.25 Motion Compensation System

A system that used to compensate the effect of vessel motions (1 to 6 degrees of motion) on the offshore access gangway structure.

7.27 Offshore Access Gangway Parking or Stowage Arrangements

The supporting structure for the gangway in its parked position on the vessel or unit deck.

7.29 Offshore Access Gangway System

An offshore access gangway system is a walkway that has one fixed end on the vessel or offshore unit and a telescopic end that extends to and may be temporarily attached to, another vessel or offshore unit. The system is intended to connect two vessels or offshore units primarily for personnel transfer.

7.31 Pedestal and Foundations

The supporting structure above which the following are mounted: the slewing bearing assembly, the revolving upper structure, or motion compensation system.

7.33 Primary Structural Member or Critical Component

A member or component whose failure would impair the structural integrity and/or result in loss of control of the offshore access gangway. See Section 2, Table 1 and Section 2, Table 2 for examples.

TABLE 1

Examples of Primary Structure

No. Member

1 Telescopic main bridge, telescopic bridge, and landing cone

2 Telescopic base frame (revolving frame and tube-structure), slew column

3 Eye plates, lugs, and brackets

4 Slew bearing (swing circle) assembly

5 Landing support structures

6 Offshore access gangway parking or stowage structure

7 Pins and shafts

8 Gangway supporting foundation, pedestal

9 Fasteners in the load path of all primary structural members

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 16

TABLE 2

Examples of Critical Machinery Components

No. Component

1 Torque transmitting components of luffing, slewing and telescoping mechanism, such as drive motors, winches, drums, shafts, gears, bearings, and brakes

2 Luffing, slewing, and telescoping hydraulic cylinders

3 Motion compensation system and hydraulic cylinders

7.35 Slew Bearing Assembly (Swing Circle Assembly)

Slew bearing (swing circle) assembly is the connecting component between the offshore access gangway’s revolving upper structure and the pedestal. This component allows gangway horizontal rotation and sustains the moment, radial, and axial loads imposed by the gangway’s operations.

7.37 Telescopic Bridge

A telescopic frame structure used for extension of the gangway.

7.37 Telescopic Drive

The machinery providing telescoping movement for the telescopic bridge.

7.41 Telescopic Main Bridge

The main frame of the gangway with one end attached to the slewing and luffing machinery. It is the pathway through which the telescopic bridge extends.

9 Certification of Components Offshore access gangway components are to be certified in accordance with Section 2, Table 3. For applicable requirements for each component, refer to the respective sections of this Guide.

TABLE 3

Offshore Access Gangway Components Certification(1)

Component(2)

ABS

Design Review

ABS

Unit

Certification Additional Notes

1 Certified Safe Electrical Equipment Type-tested certified by a competent, independent testing laboratory for compliance with IEC Publication 60079 or equivalent or ABS Type Approved

2 Electrical Cables Construction to be in accordance with the standards specified in 4-8-4/9 of the Marine Vessel Rules or ABS Type Approved.

3 Sensors and Communications System Type-tested certified by a competent, independent testing laboratory for compliance with IEC Publication 60079 or equivalent or ABS Type Approved

4 Electrical Motors ≥100 kW(3) X X

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 17

Component(2)

ABS

Design Review

ABS

Unit

Certification Additional Notes

5 Electrical Motors <100kW(3) X Test certificate furnished by the manufacturer. Testing witnessed by the Surveyor after installed of the offshore access gangway.

6 Flexible Hoses and Hose End Fittings X Design approved by ABS or, alternatively ABS Design Assessment Certificate (PDA)

7 Slewing, Luffing, Telescoping Winches/ Gears ≥100 kW(3)

X X

8 Slewing, Luffing, Telescoping Winches/ Gears <100 kW(3)

X Integrated gear boxes are to be design verified if located between the braking safety device and the load.

9 Critical Hydraulic Cylinders (including Piston Rods)(3)

X X

10 All other Hydraulic Cylinders (including Piston Rods)

X Design review in accordance with 4-6-7/3.5.5 of the Marine Vessel Rules.

11 Internal Combustion engines ≥100 kW(3) X X

12 Internal Combustion Engines < 100 kW(3)

Manufacturer’s affidavit for compliance with good commercial and marine practice.

Testing witnessed by the Surveyor after installed of the offshore access gangway.

13 Loose Gear Testing as per 2/5 of the ABS Guide for Certification of Lifting Appliances (Lifting Appliance Guide), and certificate furnished by the manufacturer, as per 2-5/1.3 of the Lifting Appliance Guide.

14 Pressure Vessels and Heat Exchangers of 150 mm(6 in.) in diameter and over and Accumulators, regardless of their diameter(4)

X X Certification in accordance with Section 4-4-1 of the Marine Vessel Rules.

15 Pressure Vessels and Heat Exchangers under 150 mm(6 in.) in diameter

Acceptance based on manufacturer’s guarantee of physical properties and suitability for the intended service, provided the installation is carried out to the satisfaction of the Surveyor.

16 Slew Bearing (Swing Circle) X X

17 Wire Ropes Certificate of test furnished by the manufacture, as per 3/17

Notes:

1 For materials’ certification, refer to 3/3.

2 For components not covered by this table, refer to the appropriate sections of this Guide.

3 Applicable only for critical components, refer to Section 2, Table 2. For non-critical components, see 4/11.

4 Applicable only for pressure vessels and heat exchangers having design pressure, temperature and volume as defined in 4-4-1/1.1 TABLE 1 of the Marine Vessel Rules.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 18

S E C T I O N 3 Structural Requirements

1 General This section provides the structural design criteria for an offshore access gangway. While usually not required for the certification of the offshore access gangway itself, the designer should also be aware of other Rules, standards and regulations that can influence the design; such as IMO MSC.1/Circ. 1331, SOLAS II-1/3-9, UK HSE OTO 2001-069, ISO 7061:1993, ISO 7364:1983, etc. details refer to Appendix 1.

3 Materials All materials are to be suitable for the design environmental conditions. Materials and welding are to follow the ABS Rules for Materials and Welding (Part 2) for requirements not specifically given in the following sections. Application of international standards such as ISO 10042, EN 1090-3, EN 1999 Eurocode 9, AA Aluminum Design Manual are to be agreed upon with ABS prior to the design and fabrication.

3.1 Steel

Material for steel structural members and components of the offshore access gangways is to comply with the requirements of Chapter 2, Section 3 of the Lifting Appliance Guide.

The primary structural members and components of offshore access gangways that are considered to be critically stressed are to have the following minimum thickness and effective corrosion control:

Solid Sections: 6 mm (0.24 in.) thick

Hollow Sections (e.g., tubular bracing): 4 mm (0.16 in.) thick

For less stressed members, a minimum thickness of 4 mm (0.16 in.) is to be provided.

The interior of hollow sections is to be coated or proven watertight to the satisfaction of the attending Surveyor.

3.3 Aluminum Alloys

Aluminum materials are to satisfy recognized international standards such as EN 1090-3, EN 1999 Eurocode 9, AA Aluminum Design Manual, etc., where the effects of the heat affected zones, standard commercial sections, material grades, etc. are to be suitably considered. If EN 1999 Eurocode 9 is used, then appropriately increased design factors for offshore structures are to be used as per Norsok N-001.

The fatigue of structural details in an aluminum structure is to be checked as per EN 1999 Eurocode 9 (Part 1-3), or an equivalent standard. If the code specified S-N curves do not address a specific structural detail, ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 19 then the designer is to provide appropriate stress concentration factors, which are to be based on appropriate experimental results or suitable finite element analysis.

The use of aluminum alloys in offshore access gangway structures will be considered upon submission of the proposed specification for the alloy and the method of fabrication.

3.5 Effective Corrosion Control

3.5.1 Steel

Special protective coatings are to be applied to those structural members of the offshore access gangways where the thickness is less than 6 mm (0.24 in.) to the satisfaction of the attending Surveyor.

3.5.2 Aluminum

Corrosion protection of aluminum materials is to satisfy recognized international standards.

5 Design Loads and Conditions

5.1 Design Loads

The following loadings are to be considered, as applicable. When Coastal States have higher requirements that exceed the minimum requirements of this Guide, those requirements are to be incorporated into the design.

The maximum operational length is to be used as the length of loaded gangway.

5.1.1 Dead Loads

The self-weight of the gangway, including landing fixture (cone), cabins, hydraulic, electrical and mechanical items, etc. If the gangway is also intended to be utilized as a hose or temporary piping support between offshore units, the weight of hose or piping loads and hydraulic items are to be considered.

5.1.2 Live Loads

For a Type I gangway, the minimum live loads of 4.51 kN/m2 (460 kgf/m2, 94.2 lbf/ft2) are to be applied for global design and 5 kN/m2 (510 kg/m2, 104.5 lbf/ft2) are to be used for local design, see Section 3, Figure 1.

Section 3 Structural Requirements 3

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 20

FIGURE 1

Type I Gangway - Distributed Live Loads

For emergency lift-off condition, a live load of 5 kN/m2 (510 kg/m2, 104.4 lbf/ft2) locally distributed on the telescoping part of the gangway, see Section 3, Figure 2(a) or a minimum live load 15 kN (1.53 tf, 3.37 Ltf) applied on the gangway tip is considered, see Section 3, Figure 2(b), whichever is greater.

FIGURE 2

Type I Gangway - Live Loads for Emergency Lift-off Condition

For a Type II gangway, when the gangway is supported at two ends, due to a limited number of persons allowed on the gangway, the minimum design live load is to be two times the maximum number of persons including their carry-on equipment on the gangway, see Section 3, Figure 3.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 21

FIGURE 3

Type II Gangway - Live Load for Gangway Supported at Two Ends

When the gangway is in the uplift or cantilever condition, the design live load is to be taken as two times the maximum number of persons including their carry-on equipment, but not less than 2.4 kN (244 kgf, 538 lbf) on the extended end, see Section 3, Figure 4.

FIGURE 4

Type II Gangway - Live Load for Uplift or Cantilever Condition

For emergency lift-off condition, two times the maximum number of persons with one person in a stretcher or a minimum live load of 3.5 kN (357 kgf, 787 lbf) is to be applied on the gangway tip, see Section 3, Figure 5, whichever is greater.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 22

FIGURE 5

Type II Gangway - Live Load for Emergency Lift-off Condition

The number of persons, weights of persons and carried items, and their location on the gangway is to be agreed upon between ABS, the Manufacturer, and the Owner.

The live loads on other locations of the gangway, e.g. waiting area and stairway, are to comply with 3-1-3/1.11.3 of the ABS Rules for Building and Classing Mobile Offshore Units (MOU Rules).

5.1.3 Motion-induced Loads

Motion-induced loads are produced by the motions of the vessel/unit on which the gangway is installed and the relative motions between vessels or units when the gangway is deployed. They are specific to the vessel/unit, the location of the gangway on the vessel/unit, and the environmental conditions where the vessel/unit operates.

The basis of certification are conditions (motions and Motion-induced loads) provided by the Owner or Designer that have been established by a competent authority considering a specific vessel/unit and gangway location. The limiting environmental conditions (e.g., sea states) producing the motion effects used in the gangway’s design are to be specified by the Owner or Designer. As a minimum, the selected limiting sea states are to have a return period of one year.

The Owner or designer is to specify the following:

● Magnitudes of the motion-induced vertical, transveral and horizontal displacements and accelerations

● Phasing of these motion-induced effects

● Loads produced by these motions considering each phase of the gangway’s Operating, Transit, and Severe Storm Conditions ( 3/5)

In the absence of specific details, the vertical, transveral and horizontal accelerations and loads are to be calculated in accordance with 2-2/5.17 of the Lifting Appliance Guide.

The effects of motion compensation devices are to be considered, as appropriate.

5.1.4 Functional Loads

There may be additional global and local functional loads due to dynamic effects from lifting, lowering, slewing, telescoping, landing, angular acceleration/deceleration of rotating machinery and personnel transfer across the gangway. These functional loads are to be specified by the Owner or designer for each Operating phase. The Functional loads are to be suitably combined with co-existing vessel/unit motion-induced loads. The combination loads that produce the most

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 23

unfavorable load effects for the strength of the gangway in each Operating phase are to be considered in design.

Monitoring is to be provided to alert the gangway operating personnel that the limits of acceptable vessel/unit motions are being approached for each of the operating phases. The margin between a design limit and a value warranting imminent action (manual or automated) to limit the loads of the gangway are to be specified by the Owner or designer.

5.1.5 Wind Loads

Generally, wind loading calculations are to comply with 3-1-3/1.3 of the MOU Rules. The design wind velocity is based on the 1-minute average gust wind velocity at the gangway location and the wind profiles are to be considered in calculating the wind load. For the normal operating condition, the design wind speed is not to be less than 20 m/s (38.9 kn) for Type II gangways and

25.7 m/s (50 kn) for Type I gangways. The minimum wind velocity for all normal deployment, retrieval operations and transit conditions is not to be less than 36 m/s (70 kn).

For frame structural components, an assessment of the possibility of vortex-induced vibration due to wind on the gangway is to be included. The loads from vortex shedding and fatigue damage are to be considered for the components experiencing the vortex-induced vibration.

5.1.6 Ice and Snow Loads

A uniformly distributed loading of 490 N/m2 (50 kgf/m2, 10.5 lbf/ft2), representing wet snow or ice, is to be considered, if applicable. Refer to 3-2-2/3.3.3 of the MOU Rules.

5.1.7 Impact Loads

These are loads resulting from ‘green water’ in the Transit and Severe Storm loading conditions described in 3/5.3.2 and 3/5.3.3. It is considered that there will be no direct wave loading on the gangway or its supporting structure during the operating condition. Any additional loading due to direct waves on the gangway, or its supporting structure, is to be clearly specified and taken into consideration as accidental loads.

5.1.8 Accidental Loads

Accidental loads are loads caused by:

● Collision

● Dropped objects

● Fire

● Blast

● Extreme environmental event and its induced extreme vessel/unit motions

For a gangway that employs motion compensation system, a single failure of any component is to be treated as an event producing accidental loads.

Accidental loads are to be determined on the basis of related risk assessment. The risk assessment planning, implementation, and evaluation of generic accidental loads may refer to ABS Guidance Notes on Accidental Load Analysis and Design for Offshore Structures.

5.1.9 Miscellaneous Loads

Miscellaneous loads include those resulting from tie-downs or lashings used to secure the gangway in its stowed positions for Severe Storm and Transit conditions, and to provide restraints in the Operating condition. Due consideration is to be given to the redundancy of gangway lashings.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 24

5.3 Design Conditions

The design is to consider the relevant Operational, Transit, Severe Storm, and Accident/Damaged conditions described below, see Section 3, Table 1.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 25

TA

B

LE

D es ig n

Lo ad s A pp lie d to th e

D es ig n

C on di tio ns

D es ig n

C on di tio ns D ea d

Lo ad s Li ve L oa ds

M ot io n-in du ce d

Lo ad s Fu nc tio na l L oa ds

W in d Lo ad s

Ic e an d

Sn ow

Lo ad s Im pa ct

L oa ds Ac ci de nt al

L oa ds M is c.

L oa ds

O pe ra tin g Co nd iti on s

D ep lo ym en t

X X

X Tr an sit w in d X

O pe ra tin g St at ic

X X

X X

O pe ra tin g Co m bi ne d

X X

X X

X X

X

Re tri ev al

X X

X Tr an sit o r S to rm w in d

Re tri ev al un ex pe ct ed li ft-of f

X X

X X

X

Tr an sit C on di tio n

X X

Tr an sit w in d

X X

X

Se ve re S to rm

Co nd iti on

X X

St or m w in d

X X

X

A cc id en ta l

Co nd iti on s Em er ge nc y

Li ft-of f

X X

X X

X X

D am ag ed

X X

X X

X X

X

Im pa ct X

X X

X X

X

N ot e:

X in di ca te s t ha t t he lo ad is to b e ap pl ie d in th e lo ad in g co nd iti on s.

ABS GUIDE FOR CERTIFICATION OF OFFSHORE ACCESS GANGWAYS • 2016 26

5.3.1 Operating Condition

The operating condition consists of three phases as follows:

i) Deployment Phase. This phase consists of the short term operations required to arrange the gangway for use. The operations include movement from the stowed position, slewing, luffing, extension, landing, and, as necessary, installing supplementary supports or fastenings. The loads (see 3/5.1) to be considered are the dead, motion-induced, and wind loads appropriate to this phase.

ii) Operating Phase. This phase consists of the long-term use of the gangway for personnel transfer. In this phase the gangway is considered to be either supported at both ends or operated as a cantilever. The telescopic part of the gangway may be free to move in the longitudinal direction within the fixed part. The effects from supplementary restraints are to be considered in the design (including those from tie-downs and bumpers) and, as applicable, the longitudinal compressive force from a device used to maintain such a force in the gangway.

The load cases to be considered for this phase are as follows:

● Combined Load Case. Dead, live, motion-induced, functional, and wind loads appropriate to this phase. Depending on the design of Type II gangways, additional bumper loads applied in vertical, telescopic and transverse directions are to be considered as applicable and specified by the Designer. Upon consultation with the Owner or Designer, miscellaneous loads related to the specific design may also need to be considered; these include loads arising from the static list and trim of the vessel/ unit due, and ice and snow loads.

● Static Load Case. Maximum dead and uniform live loads.

iii) Retrieval Phase. This phase consists of the reverse of the deployment phase, so that at the end of this phase the gangway is configured for the Transit or Severe Storm conditions, which are described below. The loads to be considered are the dead, motion-induced, functional, and wind loads (3/5.1) appropriate to this phase. If the loads for the Retrieval and Deployment phases are the same, they may be treated as one.

Additionally, retrieval after an unexpected lift-off, while personnel are on the gangway, is to be evaluated.