ship construction Q& answer thickness terms

    13  explain Each of the following with regards to thickness measurements and acceptance critiria   

   a) Gauged thickness   

b)      Reserve thickness
c)       Renewal thickness
d)      Voluntary thickness adition
e)      Substantial corrosion

      

1.       Measured thickness at the location by a certified technician with a calibrated machine under the instruction of a surveyor.
2.                wastage allowance in reserve for corrosion occurring in the two and a half years between  Intermediate and Special surveys
3.          Renewal thickness; Minimum allowable thickness, in mm, below which renewal of structural
4.                members is to be carried out  t_ren = t_as-built – t_corr – t_{own  .}Thickness of a material after deducting the maximum diminution allowed is the renewal  thick ness where the replacement of the plate has to be carried out.
5.            owner/builder specified additional wastage allowance, if applicable, in mm Owners if decides to increase the thickness of a material beyond designed thickness to achieve better safety or to reduce renewal of steel during operational life
6.      measured thickness indicates a wastage in excess of 75% of the allowable margins, but within the acceptable limits. If not renewed annual inspection has to be carried out to accertain the condtion of the plating