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A: Conditions for Retention of Class [Table of Contents] C: Endorsement and Renewal of the Class Certificate

DNV-OSS-101 Rules for Classification of Offshore Drilling and Support Units

[-] Ch.1: Position Mooring Systemes for Classification
[-] Sec.5: Retention of Class
[-] B: Classification Society Involvement

Ch.1 Sec.5
B. Classification Society Involvement

Ch.1 Sec.5
B 100   Applicable rules

Ch.1 Sec.5 B
101   Vessels built under the supervision of the Society shall in general be maintained and repaired in compliance with the rules to which it was constructed, except in cases mentioned in B602.

Ch.1 Sec.5 B
102   For vessels built under the supervision of another IACS member society, the Society's rules in force at the same date as those enforced by the other society will be applied. If such date is not known the Society's rules in force at the "date of build" will be applied.

Ch.1 Sec.5 B
103   For vessels other than those covered by 101 and 102, the Society's rules for new vessels in force at the time of entry into class will be applied.

Ch.1 Sec.5 B
104   Amendments to the rules may be made retroactive.

Ch.1 Sec.5 B
105   In cases where rule amendments are made applicable to existing vessels at the first annual, intermediate or renewal survey after a specified date, or after the vessel reaches a specified age, the expiry date of the related survey time window shall determine when the rule amendments become effective.

Ch.1 Sec.5
B 200   Surveys

Ch.1 Sec.5 B
201   The objective of a survey shall be to ascertain that the vessel, its hull structure, machinery, systems and equipment are in compliance with the rules and suitable for continued safe and reliable operation.

Ch.1 Sec.5 B
202   A survey may consist of a combination of visual inspections, audits, measurements, functional testing, non-destructive testing and review of maintenance and other relevant records.

Ch.1 Sec.5 B
203   The minimum extent of prescribed periodical surveys are given in Ch.3. The Society may increase the extent of a survey when deemed necessary in order to ascertain the condition of the vessel.

Ch.1 Sec.5
B 300   Conditions and Memoranda

Ch.1 Sec.5 B
301   A Condition of Class (CC) will be imposed for the following:
—repairs and/or renewals related to damage, defect or breakdown that are sufficiently serious to affect Classification (e.g. grounding, structural damages, machinery damages, wastage over the allowable limits etc.)
—supplementary survey requirements
—temporary repairs.


Ch.1 Sec.5 B
302   The Society will issue a CC when deemed necessary to carry out examinations in order to ascertain whether damage, a defect or a deficiency has been sustained or is imminent.

Ch.1 Sec.5 B
303   A CC may contain the following:
—a description of the deficiency, defect, damage or the examination required
—required action
—due date for the required action to be completed
—possible temporary requirements imposed until the required action has been completed.

Alternatively the CC may refer to a survey report for above details.

An approved repair method may be recommended as part of the required action.

Ch.1 Sec.5 B
304   If a CC seriously affects the vessel's safety and reliability, immediate action will be required. Otherwise a time limit will be given for the action to be completed.

Ch.1 Sec.5 B
305   A CC will be deleted when the Society, through a survey or received information, has been satisfied that requested action has been satisfactory completed.

Ch.1 Sec.5 B
306   For information related to the ship, its machinery and equipment or to rule requirements, the Society may issue an Memorandum to Owner (MO). A MO may supplement information given otherwise, e.g. in the Appendix to the class certificate or the Society's "Register of Vessels".

Ch.1 Sec.5 B
307   An MO may be used in the following cases:
—exemptions from rule requirements
—accepted deviations from rule requirements
—limitations on the use of the ship or its equipment
—defects or deficiencies of no concern to class
—deleted class notations
—equipment in excess of class requirements disused
—information related to agreed survey arrangements.


Ch.1 Sec.5 B
308   Outstanding findings may be recorded as a CC or an MO. They will be given in writing at completion of surveys. Findings may also be communicated verbally during the course of surveys. Findings that have been corrected before the survey has been completed will not be recorded as CC.

Ch.1 Sec.5 B
309   The Society may at any time modify a CC or MO if considered appropriate. The owner will be notified accordingly.

Ch.1 Sec.5 B
310   CC or MO are recorded in the vessel's class status from where they will be deleted when no longer valid. The owner will be notified accordingly.

Ch.1 Sec.5 B
311   The owner will be informed of Retroactive Requirements (RR).

Ch.1 Sec.5
B 400   Survey reports and survey status

Ch.1 Sec.5 B
401   The surveyor will prepare to the customer reports on surveys carried out.

Ch.1 Sec.5 B
402   Survey reports may contain the following information, to the extent applicable in each case:
—types of surveys carried out
—certificates issued, endorsed or extended
—damage, defects and/or deficiencies observed
—confirmation that repairs have been completed and accepted by the surveyor
—CC issued or deleted
—MO issued or deleted
—RR issued or deleted.


Ch.1 Sec.5 B
403   The Society will make class status reports available to customers on the Society's Internet website, see Sec.1 B800.

It is the customer's responsibility to obtain this information from the Society's Internet website. Survey and certificate status reports, on paper, may be distributed upon request.

Ch.1 Sec.5 B
404   Any document issued by the Society in relation to surveys performed reflects the condition of the vessel at the time of the survey only.

Ch.1 Sec.5
B 500   Damage and repairs

Ch.1 Sec.5 B
501   Repairs shall in general be carried out in such a way that the original design and scantlings are restored. Possible design modifications or reduced scantlings based on current rules which are less stringent than those originally enforced, shall be approved by the Society before the repairs are carried out.

Ch.1 Sec.5 B
502   Repairs to the hull structure, machinery, systems or equipment covered by the rules shall be carried out by qualified personnel and in compliance with applicable rules, with good engineering practice and under the supervision of a surveyor.

Ch.1 Sec.5 B
503   Repairs as stipulated in 502 may be carried out without the attendance of a surveyor (e.g. during voyage) provided a repair plan is accepted by the Society in advance. A surveyor shall be called for acceptance of such repairs when completed.

Ch.1 Sec.5
B 600   Conversions and alterations

Ch.1 Sec.5 B
601   Conversions or alterations of vessels shall in general comply with the rules applicable at the time of class assignment. If current rules are less stringent than those originally in force, then the current rules may be applied.

Ch.1 Sec.5 B
602   When conversion or alteration involves modification which:
—substantially alters the dimensions or carrying capacity of the vessel (e.g. ³ 5% change in the unit's displacement), or
—changes the type of vessel, or
—changes the main class of the vessel,

the Society will decide on the rules to be applied.

Ch.1 Sec.5 B
603   If the hull structure, machinery, systems or equipment shall be converted or altered, the changes shall be documented and be approved in the same manner as for new vessels.



Ch.1 Sec.5 B
604   Conversion or alterations shall take place under the supervision of a surveyor.
A: Conditions for Retention of Class [Table of Contents] C: Endorsement and Renewal of the Class Certificate