Permissible diminution, class by class

How to read a cell. The chip under each value is the clause and the PDF page of the document held. Where a cell carries an older edition badge, the value was read from a superseded edition — the current edition sits behind a class login and is not held, so nothing here is presented as the edition in force. Schemes are not interchangeable. BV and RINA give four numbers — isolated area / item / group / zone — and each is assessed separately; a single percentage taken out of that set means nothing on its own. DNV gives a diminution coefficient k, and the limit is t_min = k · t_{gr_off}, where t_{gr_off} is the as-built thickness less any documented owner's voluntary addition. ClassNK and KR give "20 % of original thickness + 1 mm" for part of the structure and a plain percentage for the rest. CSR gives a renewal thickness t_ren built from a corrosion addition, not a percentage at all — the full corrosion-addition grid is in T10. CCS states a minimum renewed thickness as a percentage of as-built, which is the complement of a wastage percentage. None of these were converted into one another. Requirement or guidance. The LR document is titled Thickness Measurement and Close-up Survey Guidance; its §1.5 is headed Acceptance Criteria and states that repairs will be required when the percentage diminutions are exceeded. The KR wear-limit table sits in the Guidance Relating to the Rules, and KR Rules Pt 1 Ch 3 112. makes that table the acceptance criteria. The CCS document is titled Guidelines and refers the percentage criteria out to the CCS Rules. Both facts are recorded on the cells. What a percentage is taken of. The base thickness is not the same word in every scheme. KR Annex 1-5 Table 1 note 4 defines original thickness as the thickness on the drawing, but adds that where the Classification Technical Rules separately specify a required thickness for a member, that figure is followed instead. BV applies its percentage to the rule thickness, t_min = (1 − W/100) t_rule − t_wc, and allows the as-built thickness only where the rule thickness is not available. DNV applies its coefficient to the gross offered thickness, which is the as-built thickness less any documented owner's voluntary addition. ClassNK and INSB work from original and as-built thickness respectively. LR Table 1.5.5 note 6 and INSB Table C note 3 both make the limit an average — averaged over the area of a plate, or along a stiffener from one support to the next — and never a single low reading. What is not here. PRS Part I §5.1.3.6 and PRS Publication 62/P §1.5 both set the acceptance criteria by reference to the PRS Rules Part II — Hull and to IACS URs; Part II has since been read: it sets corrosion additions at the construction stage and publishes no wastage percentage, no renewal thickness and no acceptance criteria of its own, so the PRS column stands as not published, with the clause that shows where the criterion actually comes from. CCS Guidelines Chapter Three §I and §II refer the longitudinal and local strength criteria to the CCS Rules Part One Ch 5 App 1, which is not held. KR Rules Pt 1 Ch 3 106. 1 (2) sets the hull girder criterion by separate requirements of the Society, which are not held. File note. The PRS Publication 63/P held prints July 2008 in its running head; the registry entry carries no revision. Conditions are on the cells. Build-date, length and notation conditions are not summarised away — they sit in the cell they belong to.