Common Structural
Rules for Tankers
Gary Horn, P.E.
Director, Technology
ABS Houston
Houston Tanker Event 2007
Houston, TX
26 March 2007
1
IACS Common Structural Rules
AIM:
To develop a set of unified Rules and Procedures for the
determination of the structural requirements for oil
tankers and bulk carriers
2
Tanker Operations
Tanker incidents by cause 1978-2004
Source: Intertanko
3
Tanker Operations

Improvements made in
tanker operational,
safety and pollution
performances

We have “come a long
way…”

However, we wanted to
employ continuous
improvement principles
and take the next step…
Common Structural Rules intended to
enhance safety, robustness and durability.
4
IACS Common Structural Rules


CSR for Tankers

Complete Set of Structural Rules for
Double Hull Oil Tankers

Length greater than or equal to 150m
CSR for Bulk Carriers

Complete set of Structural Rules for SSS
and DSS Bulk Carriers

Length greater than or equal to 90m
5
Features of the new CSR
1.
Rules are to result in common scantling
requirements
2.
Net scantling approach includes a clear link
between newbuilding strength checks and inservice gauging review standards
3.
Include coating standard criteria
4.
Fatigue standard enhanced to include exposure
to North Atlantic environment with minimum life
of 25 years
5.
Includes the results from industry input and
feedback
6
IACS Common Structural Rules

Tankers
Section
Topic
Section
Topic
1
Introduction
9
Design Verification
2
Underlying Principles
10
3
Rules Applications
Buckling and UltimateStrength
4
Basic Information
11
General Requirements
5
Structural Arrangement
12
Renewal Criteria (SiO)
6
Material and Welding
A
Hull Girder Ultimate Strength
7
Loads
B
Structural Strength Assessment
8
Scantling
Requirements
C
Fatigue Strength Assessment
D
Buckling Strength Assessment
7
CSR/Tanker - Overview
Loads
Design Requirements
Design
Requirements
Operational
Requirements
Section 2/4
Static Loads
Section 7/2
Dynamic Loads
Section 7/3
Design Basis
Section 2/5
Accidental Loads
Section 7/5
Loads
Dynamic Load
Combination Factors
DLCFs Section 7/6.5
Load Combinations
Section 7/6
Loading Manual
Section 8/1
General
Rule Requirements
Static Load
Combinations
Section 7/6
General
Rule
Requirements
Basic Information
Section 4
Static Plus Dynamic
Load Combinations
Section 7/6
Impact and Sloshing
Loads
Section 7/4
Structural
Arrangements
Section 5
Scantling Requirements
Materials
Section 6
General Detailed
Requirements
Section 11
Plating and Local
Support Members
Section 8/2
Longitudinal Strength
Section 8/1
Primary Support
Members Inc Bhds
Section 8/2.6
Scantling
Requirements
Minimum
Requirements
Minimum Thickness
Section 8/2
Minimum
Requirements
Stiffness and
Proportions
Section 10/2
Hull Girder Inertia
and Section Modulus
Section 8/1
Fore and Aft Ends
Section 8/3 & 8/5
Deck houses
Section 11/1
Machinery Space
Section 8/4
Structural design
details (welding,
brackets)
Section 4/3
Sloshing and Impact
Section 8/6
Other Minimum
Requirements
Criteria Assessment
Yield, Shear,
Buckling
Design Verification
Hull Girder Ultimate
Strength
Section 9/1
Strength Assessment
(FEM)
Section 9/2
Fatigue Strength
Section 9/3
Design Verification
Global Cargo Tank
Structural Strength
Analsis
Appendix B/2
Criteria Assessment
Local Fine Mesh
Structural Strength
Analysis
Appendix B/3
Criteria Assessment
Yield, Shear,
Buckling
Nominal Stress
Approach
Appendix C/1
Hot Spot Stress (FE)
Approach
Appendix C/2
Criteria Assessment
Fatigue Damage
Evaluation of Hot
Spot Stress for Fatigue
Analysis
Appendix B/4
8
CSR & Coating Performance Standards

Promote effective use of protective coatings

Provide a protective barrier to delay onset of corrosion,
noting;


Corrosion wastage allowance is still included in rules
Wastage allowances are not reduced due to presence of coatings

Target useful coating life of 15 years

Added benefit – facilitate in-service inspection

Top coat to be a light color to easily distinguish from rust
Protective Coating
Wastage
Allowance
Predicted
corrosion
in 2.5 years
(0.5 mm)
Required
Renewal
Thickness
Annual
Thickness
Measurements
9
Coating Performance Standards
IMO Res MSC.215(82) Performance Standard for
Protective Coatings for Dedicated Seawater Ballast Tanks
in All Types of Ships and Double-Side Skin Spaces of Bulk
Carriers
IACS PR No. 34, IACS Procedural Requirement on
Application of the IMO PSPC under IACS Common
Structural Rules for Bulk Carriers and Oil Tankers
IACS Common Interpretation and answers to
frequently asked questions on IACS website
www.iacs.org.uk
ABS Guide for the Class Notation Coating
Performance Standard (CPS), December 2006
10
CSR Rule Status

CSR - effective date 1 April 2006

Tanker updates:

Corrigenda 1 – effective date 1 April 2006

Corrigenda 2 – effective date 1 April 2006


Rule Change Notice (RCN) No. 1 – effective date 1 April 07 or
earlier if agreed between yard and owner
All future updates to follow IACS process:

PR32

Hull Panel

Project Teams

Rule updates and maintenance

Rule interpretations, Q/A
11
CST/Tanker RCN No.1

Effective 1 April 2007, may be applied earlier if agreed
by builder and owner.

Can not be partially applied

Contents:

Corrosion additions for heated cargo tanks

Clarification of heavy ballast condition

Buckling assessment in way of bottom portion

FE analysis of tight floor, girders and webs

Slenderness ratio of bulb profiles

Deck equipment welding

Tolerance of hopper knuckle connection
12
Oil Tanker Orders - Gross Tons
Source of feedback…
Oil Tanker N/C Contracts
6,000
Monthly KGT
Worldwide
4,000
2,000
0
May-06
Jun-06
Jul-06
Aug-06
Sep-06
Oct-06
Nov-06
Dec-06
Jan-07
Feb-07
13
Oil Tanker Orders – Number of orders
Source of feedback…
Oil Tanker N/C Contracts
100
Monthly Count
Worldwide
80
60
40
20
0
May-06
Jun-06
Jul-06
Aug-06
Sep-06
Oct-06
Nov-06
Dec-06
Jan-07
Feb-07
14
IACS Project Teams for CSR Maintenance

IACS implemented 2 Project Teams for CSR Maintenance

Active from 1st June 2006

PT for Bulk Carriers: 3 JBP + 1 JTP members

PT for Oil Tankers: 3 JTP + 1 JBP members

Rotation among members every 2 years

Running of the PT governed by IACS
procedure
IACS COUNCIL
PERMANENT
SECRETARIAT
R. Leslie
HULL PANEL
Chairman: T. Yoneya
CSR Bulk Carriers
CSR Oil Tankers
SG/CSR
NK, LR, BV, ABS
CSR Secretariat
G-Y Han
S. HARADA
Project Manager
ClassNK
G. CESARINE
BV
P. SALTVEDT
Project Manager
DNV
F. CHENG
LR
A. Schulz-Heimbeck
GL
K. ABE
ABS
R. NAGAYAMA
ABS
P. BAUMANS
BV
15
IACS CSR Knowledge Center/Database

Centralized mechanism for collecting, categorizing and storing
questions and answers, feedback and responses, tasks and
pending actions, interpretations and rule changes

Basis for future improvements

External access to Q&A and Interpretations from IACS Web
Site
Transparency and consistent
implementation of the Rules
16
GBS Overview
IMO

Basic Principles of Goal-Based Standards

Broad, over-arching safety, environmental
and/or security standards that ships are
required to meet during their lifecycle

The required level to be achieved by the
requirements applied by Class Societies
and other ROs, Administrations and IMO

Clear demonstratable, verifiable, long
standing, implementable and achievable
irrespective of ship design and technology;
and

Specific enough in order not to be open to
differing interpretations
17
GBS Overview
IMO
Tier I
Tier II
Goals
IMO
Functional
Requirements
Tier III
Verification and
Acceptance criteria
Tier IV
Requirements, Rules and
Industry Standards
Tier V
Procedures and Quality Systems
IMO
IMO
IACS
Industry
18
Influence of GBS on future CSR developments

Structural residual strength: the CSR partially cover the
GBS intent, but additional work necessary to define
assumed extent of structural damage, environmental loads
and acceptance criteria

Structural redundancy: the CSR partially cover the GBS
intent, but additional work necessary to develop method to
confirm structural redundancy and structural hierarchy

Reference to other standards: cross reference other
regulations or standards





Human element
Design transparency
Survey and maintenance
Structural accessibility
Recycling considerations
19
Why Common Structural Rules?
An improved structural
standard.
A major aspect in a
complex yet integrated set
of initiatives with the goal
of improving performance
for the safety
of life, property and the
marine environment.
20
Thank you
Common Structural
Rules for Tankers
Gary Horn, P.E.
Director, Technology
ABS Houston
21