Guide Of Remedial Actions For Areas With Pitting In Blocks-ver A

Procedure for verification of block pitting condition and actions

Applicable rules of IACS 1.Regulations UR_W-item W13.3.2 , stating that minus tolerance of thickness of steel rolled products is 0.3 mm,irrespective of nominal thickness. Procedure steps.

1. Yard CQ ,under the monitoring of Engineering department ,measures the reduction of plating in the area of pitting and registers the area of pitting and the total area of the structure concerned.Then CQ makes a report with photos,thickness measurements drawings as necessary. 2. CQ submits to Engineering Department for Evaluation and definition of actions to be taken. 3. The Engineering department determines the pitting area percentage and the thickness loss for the pitted area and refers to above checks them according to the below, applicable IACS Rules ,as follows. 3.1 All areas found within accepted standards,if uncoated,should be treated to ST 2 minimum surface standard and coated with modified epoxy high built coating (or equivalent) to min thickness 600 microns. 3.2 The areas presenting pitting area without plate thickness loss and with scattered pitting of max 0,3 mm depth,will be accepted without futher actions,except - if uncoated - of the treatment to ST 2 minimum surface standard and coating with modified epoxy high built coating (or equivalent), to min thickness 600 microns. 3.3 In the case that the pitting area plate thickness loss is above the applicable rules tolerances,remedial measures should be taken and approved by both ABS and Owners.

An explanatory Flowchart has been also created as part of these procedures and is included herebelow.

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Legend of Symbols used in the Pitting remedial measures procedure Flowchart For each area of significant pitting found in the construction blocks,the following patameters should be determined :

tN

= Nominal plate thickness ,as in the construction drawings

tP = tR

Minimum acceptable plate thickness by the Project,if less than tN

= Remaining plate thickness in way of pitting ,calculated as the arithmetic

mean of ultrasonically measured thicknesses, of a sufficient number of points ,covering the affected area .

d

= Remaining pitting depth,estimated after removal of scale and paint from the

affected area surface,by grinding.

COATING CONDITION =

Condition of Coating of affected areas ,in the

conclusion of remedial actions.It can be either COATED or UNCOATED

P% = Percentage of pitted area as a ratio of the total pitted area divided by the total area of the plating concerned

Written 30/06/2015 Eng.Spiridon Gianniotis

PROCEDURE OF PITTING TREATMENT START

BLOCK INSPECTION AND DETERMINATION OF FOLLOWING PARAMETER FOR EACH PITTING AREA

N

P

(mm)

YES

R=

(mm)

%

i (mm) (mm)

COATING CONDITION

(mm)

(ACC URW13) P-

R ≤ 0.3

NO START EXAMINATION OF REMEDIAL MEASURES BY ERG (QC+ENGINEERING)

REMEDIAL MEASURES NECESSARY BY INSERTING NEW PLATING IN WAY OF PITTING

APPLICATION OF MODIFIED EPOXY PAINT COATING IN AREA REMANING WITH PITTING COATING THICKNESS TO BE MINIMUM 600 MICRONS

i

YES

PITTED AREA PAINTED AS PER PROJECT?

ABS + OWNERS APPROVAL OF REMEDIAL MEASURES NO

EXECUTION OF REMEDIAL MEASURES ACTIONS APPLICATION OF COATING MIN 150 MICRONS

ST2 MINIMUM OF HYDROBLASTING PREPARATION OF UNCOATED AREAS AFTER REMEDIAL ACTIONS

PITTING AREA PHOTOS