Crack assessment criteria for ship hull structure based on ship operational life

Figures & data

Table 1. Crack inducement factors along with causes/reasons

Inducement factor	Causes/reasons	Reference
Design	Inadequate strength and support of structural members	ISSC (2009), Stambaugh and Wood (1987)
	Incorrect prediction of loads	Beghin (2006)
	Abrupt dimensional changes, Use of different material type or grade, Use of High tensile steel sections	Blagojevic et al. (2002), Lloyd’s Register of Shipping (LR, 2009), ISSC (2009), Beghin (2006)
	Complex weld geometry, inappropriate weld type and weld size	ISSC (2009), Lloyd’s Register of Shipping (LR, 2009), Beghin (2006), Fricke and Kahl (2008)
Welding process	Improper weld	Beghin (2006), Mann (2011)
	Presence of weld impurities – slag, porosity, contamination etc.	Beghin (2006)
Fabrication and workmanship	Geometrical misalignment	Blagojevic et al. (2002), Beghin (2006), Chakarov, Garbatov, and Soares (2008), Barsom and Rolfe (1999)
	Presence of notches and structural discontinuities	Lloyd’s Register of Shipping (LR, 2009), Stambaugh and Wood (1987)
	Block assembly issues and welding sequence	Fu, Lourenço, Duan, and Estefen (2016)
Material properties	Use of thick steel sections	Lloyd’s Register of Shipping (LR, 2009), Mann (2011)
	Non homogeneous material composition	Mann (2011)
Temperature	Prolonged exposure in low temperature areas	ISSC (2009), Stambaugh and Wood (1987)
	Nature of Cargo	ISSC (2009)
Accident	Dent and deformation in structure due to dropped object, contact, slamming, pounding etc.
Fatigue	Corrosion	ISSC (2009), Garbatov and Soares (2011), Beghin (2006)
	Welding process	Beghin (2006), Mann (2011)
	Fabrication and workmanship	Beghin (2006), ISSC (2009)
Corrosion		Beghin (2006), Blagojevic et al. (2002), Kwon and Frangopol (2012), Saydam and Frangopol (2013), Garbatov and Soares (2011)

Figure 1. A crack initiation case due to accident related inducement factor.

Figure 2. Interaction and cascading effect of Inducement factors contributing to crack initiation/formation.

Figure 3. Age based crack assessment criteria for ship hull structure.

Figure 4. Crack at weld section between side shell and side shell longitudinal.

Table 2. Procedure for crack assessment using the age based crack assessment criteria diagram

Step 1	Step 2	Step 3		Step 4	Step 5	Remarks
Age of ship	Inspection findings	(Causes/reasons)		Validation method	Inducement factor selected
(Refer AR-1)	(Refer AR-4)	(Refer AR-3)		(Refer AR-5)	(Refer AR-2)
		Possible causes/reasons	Onsite observations
0–5 years	Identify crack in the structure inspected i.e. crack at the weld joint connecting side shell and shell longitudinal	Inadequate strength of the structural member	Structural member size similar to other similar connections
		Complex weld joint, weld type and weld size	Fillet weld. Weld type and size similar to other similar connections. No crack initiation noted at other locations
		Inadequate fusion, undercut, non fused root faces or partial or fillet welds	To be investigated	N
		Presence of weld impurities	To be investigated	N	Welding Process	Non destructive examination shows weld impurities
		Geometrical misalignment	None seen
		Dents and deformations	None seen

Notes: VI – Visual indication; SC – Structural calculations; FEA – Finite Element Analysis; N – Non Destructive Examination; AR – Annular Ring.

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