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B: Selection of Material [Table of Contents] Sec.3: Classification of

DNV-OS-C102 Structural Design of Offshore Ships

[-] Sec.2: cture and elements not covered by Rules for
[-] C: Inspection Principles

Sec.2
C. Inspection Principles

Sec.2
C 100   General

Sec.2 C
101   The purpose of inspection is to detect defects that may grow into fatigue cracks during service life.

Sec.2 C
102   When determining the locations of required non-destructive testing (NDT), consideration should be given to relevant fabrication parameters including:
—location of block (section) joints
—manual versus automatic welding
—start and stop of weld.

Sec.2
C 200   Hull structure

Sec.2 C
201   For the inspection principles for hull structure, see unit specific provisions Sec.11 and Sec.12.

Sec.2
C 300   Topside structure and elements not covered by hull structure requirements

Sec.2 C
301   Fabrication and testing of topside structure shall comply with the requirements in DNV-OS-C401. The requirements are based on the consideration of fatigue damage and assessment of general fabrication quality.

Sec.2 C
302   The inspection categories are related to the material class and structural categories as shown in Table C1.

Sec.2 C
Table C1 Inspection categories 
Inspection Category Material Class Equivalent structural category in the DNV OS- standards 
I IV Special 
II III Primary 
III I, II Secondary 



Sec.2 C
303   The weld connection between two components shall be assigned inspection category according to the highest of the joined components. For stiffened plates, the weld connection between the plate and stiffener, stringer, and girder web to the plate may be inspected according to inspection category III.

Sec.2 C
304   If the fabrication quality is assessed by testing, or well known quality from previous experience, the extent of inspection required for elements within material class III may be reduced, but not less than for inspection category III.

Sec.2 C
305   Fatigue critical details within material class II or III shall be inspected according to requirements in inspection category I.

Sec.2 C
306   Welds in fatigue critical areas not accessible for inspection and repair during operation shall be inspected according to requirements in inspection category I.

Sec.2 C
307   The extent of NDT for welds in block joints and erection joints transverse to main stress direction shall not be less than for inspection category II.

Sec.2 C
308   Topside stools, or topside - hull connections, material class III, shall be inspected according to the requirements in inspection category I for the areas shown in Figure 1.

Sec.2 C
309   Inspection categories for offshore crane pedestals connection to deck are given in Figure 2.

Sec.2 C
raster  Where:
Length 'a' to be 0.35l, minimum 120 mm
'a' does not need to be bigger than 500 mm 

Fig. 1   Inspection categories for topside stool with soft nose brackets
 
raster   raster  

Fig. 2   Inspection categories for offshore crane pedestal
 

B: Selection of Material [Table of Contents] Sec.3: Classification of