DNV GL rules for classification: Ships – July 2017

The July 2017 edition of DNV GL rules for classification: Ships is now available.

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1. General information
   New and amended rules were formally approved on 6th June 2017 and are included in the July 2017 edition of the rules. Entry into force date is in general 1st January 2018. However, please note that certain chapters of the hull related ship rules (Pt.3) will enter into force 1st July 2017. The changes to the rules may be divided into three categories:
   1. New class notations
   2. Implementation of external requirements (IACS unified requirements and relevant IMO codes)
   3. General updates and corrections
   In addition to the updates to the DNV GL ship rules, there have also been minor updates to DNV GL rules for classification: High speed and light craft and DNV GL rules for classification: Yachts. For accurate and detailed information on all rule sets, please visit DNV GL rules and standards.
   
   
2. DNV GL rules for classification: Ships
   Below is a general overview of the main changes in the DNV GL ship rules:
   • New class notations

   • Additional class notations:

     • CMON - Construction monitoring (Pt.6 Ch.9 Sec.7)

   • Revised class notations

   • R - Service area notation (Pt.1 Ch.2 Sec.5)

     Ship type notations:

     • Escort tug (Pt.5 Ch.10)
     • Barge and Pontoon (Pt.5 Ch.11)
     • Fishing vessel (Pt.5 Ch.12)

     Additional class notations:

     • Hatchcoverless (Pt.6 Ch.5 Sec.2)
     • HMON - Hull monitoring systems (Pt.6 Ch.9 Sec.4)

• Changes to material related topics (Pt.2)

Rule reference	Description
Pt.2 Ch.2
	Introduces duplex stainless steel
Pt.2 Ch.4
	Alignment with IACS UR W32 Qualification scheme for welders of hull
	Structural steel IACS UR Z23 Ship construction file review IACS UR Z23 Ship construction file review
	Compartments

• Changes to hull related topics (Pt.3 and Pt.5)

Following the new technical platform for hull structures introduced with the DNV GL rules in October 2015, further updates have been carried out to streamline the application and refine scantling impact.

Please note that changes marked with * come into force with immediate effect, i.e. from 1st July 2017. .

Rule reference	Description
Pt.3 Ch.3 Sec.6*
	Clarification related to tripping brackets for inclined stiffeners. Added criteria for brackets with unequal arm lengths – CSR based. Taper ratio of PSM flanges aligned with common yard standards.
Pt.3 Ch.4 Sec.5*
	Corrected error as the reduction factor fa=0.9 for the sea pressure used in fatigue calculations has been inserted in the pressure formula for OST load cases.
Pt.3 Ch.4 Sec.6*
	Tank testing design pressure is removed for cofferdams, in line with 2017 corrigenda 1 of CSR.
Pt.3 Ch.6 Sec.7*
	Requirement of double sided connection/brackets on top of L3 stiffeners (flange welded on one side of the web) removed.
Pt.3 Ch.10 Sec.1
	Correction of pressure definition of bow impact pressure on bulwark. New requirement to deck transverse web in line with web frame at the side has been introduced.
Pt.3 Ch.10 Sec.2
	Bottom slamming requirement for floors, the slenderness coefficient has been increased from 90 to 100; i.e. 10% reduction.
Pt.3 Ch.10 Sec.4
	The application of liquid impact rule pressure is limited to tanks with length equal to or less than 0.16L.
Pt.3 Ch.10 Sec.6
	Web frames supporting side longitudinals subjected to berthing impact, modified formula and changed to gross scantling.
Pt.3 Ch.12
	Glass panes; alignment with ISO for local requirements for window mounting frames.
Pt.3 Ch.12 Sec.3
	Requirements to fitting signboards and indications for watertight doors and hatches have been implemented.
Pt.3 Ch.14 Sec.1
	Rudder stock connection; reduced minimum required outer diameter of gudgeon to 1.25 times mean diameter; in accordance with previous DNV rules and industry practice.
Pt.5 Ch.1
	Aligned global FEA for general dry cargo ships with other parts of rules.
Pt.5 Ch.3 Sec.2
	Defined allowable stress for internal hoistable ramps when lifting cargo.

• Changes for system related topics

Rule reference	Description
Pt.4 Ch.6
	Scrubbers: Implemented IACS UR M77 for SCR systems. Non-metallic pipes: Aligned test procedure with IMO Res. A753(18). Certification requirements for vent heads and expansion bellows adjusted to Type Approval.
Pt.5 Ch.7 Sec.1
	Added requirement for certification of cargo bellows
Pt.5 Ch.7 Sec.13
	Updates rules to cover all types of reliquefication plants.

• New class notations
  • Construction monitoring (Pt.6 Ch.9 Sec.7)
    1. Modern rules and calculation tools allow an identification of structural elements with high utilization.
    2. Provides extended documentation and follow up of highly loaded structural elements during construction and operation.

• Other significant changes
  • Service area notation (Pt.1 Ch.2 Sec.5)
    1. Provides a corresponding maximum sea state to each of the service area notations.
    2. Further provides correlation between given service area notation, load level applied for hull strength and significant wave height.
  • Escort tug (Pt.5 Ch.10).
    1. Introduced numerical methods as an alternative to full scale test as means to establish the escort rating numbers
  • Non-self-propelled units (Pt.5 Ch.11).
    1. Introduced the significant wave height as alternative dimensioning parameter for hull loads.
  • Fishing vessels (Pt.5 Ch.12)
    1. Made RM notation (Pt.6 Ch.4 Sec.10) mandatory for fishing vessels with refrigerated cargo holds
  • Hatchcoverless (Pt.6 Ch.5 Sec.2)
    1. Established requirements for MPVs and dry cargo ships to operate with open hatch covers.
    2. Requirements are established based on MSC/Circ. 608/Rev. 1 Interim guidelines for open-top containerships.
  • Hull monitoring (Pt.6 Ch.5 Sec.4)
    1. Extended the application of the notation and by this given the possibility for tailor made solutions by having added new qualifiers for:
       1. Ice thickness
       2. Ice response
       3. Parametric roll
       4. Vibration dose
    2. Improved available bridge information