Common Structural Rules - Common Structural Rules for Bulk Carriers and Oil Tankers, January 2019 - Part 1 General Hull Requirements - Chapter 9 Fatigue - Section 3 Fatigue Evaluation - 7 Workmanship
7 Workmanship
7.1 Application
7.1.1
In general, the fatigue performance of structural details can be improved by adopting enhanced workmanship standards, which include building alignment and weld control.
7.2 Workmanship control for construction details
7.2.1 Building alignment and tolerance control
Building alignment exceeding construction tolerance could introduce additional stress concentration for structural details, reducing the fatigue performance. The builder is responsible to comply with the construction requirements given in Ch 12, Sec 1.
7.2.2 Weld profile control
Poor weld geometry could introduce additional stress concentration; therefore special attention should be given to achieving a favourable geometry and smooth transition at the weld toe. Weld profile control, i.e. enhanced workmanship may be required by the Society in way of critical weld toe locations.
The weld notch stress concentration is a direct function of the weld flank angle and the weld toe radius.
The validity of the aforementioned S-N curves is based on a weld flank angle with a maximum mean value of 50 deg and on a weld toe radius with a minimum mean value of 0.5 mm. Welding details may be requested to be submitted for approval for some critical areas considering the calculated fatigue life.
7.2.3 Post-weld treatment methods
Post-weld treatment methods may be used to improve fatigue resistance of structural detail, as specified in [6].
At the design stage, the calculated fatigue life should not generally take into account any benefit that may be derived from such treatment. This benefit should only be considered in exceptional cases when the design fatigue life can not reasonably be achieved by adopting alternative design measures such as improvement of the shape of the cut-outs, soft brackets toes, local increase in thickness or other changes in geometry of the structural detail. This is to be considered on a case-by-case basis by the Society.
7.2.4 Detail design standard
Requirements for improved design of structural details are provided in Ch 9, Sec 6. The detail design standard also includes workmanship and welding requirements.
| Copyright 2020 Clasification Society, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasification Society, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasification Society'. Clasification Society Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasification Society entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract. |  |