ABS: Application of thick steel plates in container carriers

The American Bureau of Shipping has updated its Guide for Application of Higher-Strength Hull Structural Thick Steel Plates in Container Carriers.

This Guide was issued on March 1st, 2023, and became effective on the same date.

Foreword

Over the last several decades, the drive for increasingly efficient sea-borne container transportation has led to significant growth in the size of container carriers.

Application of hull structural thick steel plates in the upper flange of large container carriers is a natural choice for the hull structure to meet the required hull girder strength.

Steel plates well in excess of 50 mm (2 in.) in thickness are commonly found in large container carriers.

More recently, one significant technical innovation on the next generation of container carriers is the application of hull structural thick steel plates with a minimum yield stress of 460 N/ mm2 (47 kgf/mm2, 67 ksi) (H47), as well as the application of brittle crack arrest steel.

Higher-strength thick steel plates have been designed and applied to upper deck region* longitudinal structural members including the topmost strakes of the inner hull or bulkhead, the sheer strake, main deck, hatch coaming side plate, coaming top plate, and all attached longitudinal stiffeners.

*The upper deck region is defined as the upper deck plating, hatch side coaming plating, hatch coaming top plating, and their attached longitudinals.

In addition to the ABS Rules for Building and Classing Marine Vessels (Marine Vessel Rules), this Guide provides supplementary requirements for the application of higher-strength hull structural thick steel plates, greater than 50 mm (2 in.), in large container carriers.

For thick steel plates with a minimum yield stress of 390 N/mm2 (40 kgf/mm2, 57 ksi) (H40), the requirements reflect a large and successful body of experience with large container carriers in service, considering the first principles structural analysis methodologies and the experience in material, welding, and construction routinely applied to large container carriers.

Also, in response to requests from industry for the adoption of H47 steel grade and brittle crack arrest steel, this Guide provides guidance on the design, construction and operation, of container carriers built with such high strength steel.

This Guide provides the requirements for the optional notation, EBCAD (Enhanced Brittle Crack Arrest Design), for the enhanced BCA application of higher-strength hull structural thick steel plates in container carriers.

The January 2021 edition also updated the requirements for H47 steel and brittle crack arrest steel and introduced a new Appendix 8 on engineering critical assessment for hatch coamings.

The February 2021 edition aligned the long-term distribution factor in A1/5.5 with the Marine Vessel Rules.

The March 2022 edition aligns the wave bending moment in A2/3 with 5C-5-A4a/3.5.2 of the Marine Vessel Rules.

This March 2023 edition introduces optional notations WIP and SPR, which denote that the strength and fatigue performance of the hull structure is evaluated considering the effects due to whipping and springing, respectively.

General

This Guide describes supplementary requirements for the application of higher-strength hull structural steel plates with or without specified brittle crack arrest (BCA) properties in container carriers with regards to the following:

Hull structural design with higher-strength thick steel plates
Requirements for H47 Non-BCA steels (H47 steels without specified BCA properties)
Requirements for H36/H40/H47 BCA steels (H36/H40/H47 steels with specified BCA properties)
Welding and fabrication of higher-strength thick H47 Non-BCA and BCA steel plates
Prevention of fatigue and fracture failure of higher-strength thick steel plates

These requirements for thick steel plates are to be used in conjunction with the following ABS Rules:

Part 5C, Chapter 5 “Vessels Intended to Carry Containers 130 meters (427 feet) to 450 meters (1476 feet) in Length” of the ABS Rules for Building and Classing Marine Vessels (Marine Vessel Rules) for the scantling and strength requirements.
Chapter 1 “Materials for Hull Construction” of the ABS Rules for Materials and Welding (Part 2)
Chapter 4 “Welding and Fabrication” of the ABS Rules for Materials and Welding (Part 2)
ABS Rules for Survey after Construction (Part 7)

For thick steel plates in the upper flange of the hull structure, fatigue and fracture are two most pertinent failure mechanisms.

When the hull girder strength is designed to meet rule minimum requirements, the accompanying effects of higher-strength thick steel plates are largely associated with higher stress levels and reduced fatigue and fracture strength characteristics.

In the upper flange of the hull structure, waveinduced fatigue damages in way of thick plated weld connections are the first and foremost concern.

As a countermeasure, the fatigue behavior of these weld connections is to be extensively evaluated to avoid initial crack initiation.

Second, the presence of planar flaws in thick plated weld connections can adversely affect the integrity of these connections in the form of accelerated crack growth and fracture.

Satisfactory fatigue and fracture characteristics are to be attained from improvements in structural design measures, steel materials, welding consumables, welding procedures and post-weld enhancements.

Third, survey after construction is to be enhanced through monitoring critical areas and nondestructive inspection.

Application

For H36/H40 steel grade, the supplementary requirements in the Guide are applicable to steel plate thicknesses greater than 50 mm (2 in.) and up to 100 mm (4 in.) used in the upper deck region* of a container carrier hull structure.

*The upper deck region is defined as the upper deck plating, hatch side coaming plating, hatch coaming top plating, and their attached longitudinals.

For H47 steel grade, the supplementary requirements in the Guide are applicable to steel plate thicknesses up to 100 mm (4 in.) used in the upper deck region of a container carrier hull structure.

For H36/H40/H47-BCA steel grades required by Subsection 2/3, the BCA properties are to be in accordance with Subsection 3/5.

BCA steels are applicable to steel plates with thicknesses greater than 50 mm (2 in.) and up to 100 mm (4 in.).

The application of steel plates with thicknesses greater than 100 mm (4 in.) is subject to special consideration and approved by Classification Society.

The supplementary requirements and BCA properties requirements in this Guide are applicable to the Cargo Hold Region.

If you need more information, please visit the ABS Rules and Guides page, where the document is available FOR FREE.