2.1 Criteria for renewal or other measures
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Statutory Documents - IMO Publications and Documents - Resolutions - Maritime Safety Committee - Resolution MSC.168(79) - Standards and Criteria for Side Structures of Bulk Carriers of Single-Side Skin Construction - (Adopted on 9 December 2004) - Annex 2 - Renewal Criteria for Side Shell Frames and Brackets in Single-Side Skin Bulk Carriers not Built in Accordance with the Standards for Side Structures in Single-Side Skin Bulk Carriers - 2 Renewal or other measures - 2.1 Criteria for renewal or other measures

2.1 Criteria for renewal or other measures

Parent topic: 2 Renewal or other measures

2.1.1 Symbols used in 2.1

tM = thickness as measured, in mm
tREN = thickness at which renewal is required (2.1.2)
tREN,d/t = thickness criteria based on d/t ratio (2.1.2.1)
tREN,S = thickness criteria based on strength (2.1.2.2)
tCOAT = 0.75 tS12
tS12 = thickness, in mm, as required by annex 1 in paragraph 3 for frame webs and in paragraph 4 for upper and lower brackets
tAB = thickness as built, in mm
tC = See table 1 below

Table 1 tC values, in mm

Ship's length L, in m Holds other than No.1 Hold No.1
Span and upper brackets Lower brackets Span and upper brackets Lower brackets
≤100 2 2.5 2 3
150 2 3 3 3.5
≥ 200 2 3 3 4

Note For intermediate ship lengths, tC is obtained by linear interpolation between the above values.

2.1.2 Criteria for webs (shear and other checks)

 The webs of side shell frames and brackets shall be renewed when the measured thickness (tM) is equal to, or less than, the thickness (tREN) as defined below:

tREN is the greatest of:

  • .1 tCOAT - tC

  • .2 0.75 tAB

  • .3 tREN,d/t

  • .4 tREN,S (where required by 2.1.2.2)

2.1.2.1 Thickness criteria based on d/t ratio

 Subject to b) and c) below, tREN,d/t is given by the following equation:

where:
R = for frames
= 65 k0.5 for symmetrically flanged frames
= 55 k0.5 for asymmetrically flanged frames
R = for lower brackets (see a) below):
= 87 k0.5 for symmetrically flanged frames
= 73 k0.5 for asymmetrically flanged frames
k = 1 for ordinary hull structural steel;
k = 0.78 for steel with yield stress of 315 N/mm2; and
k = 0.72 for steel with yield stress of 355 N/mm2.

In no instance shall tREN,d/t for lower integral brackets be taken as less than tREN,d/t for the frames they support.

  • a) Lower brackets

    In calculating the web depth of the lower brackets, the following shall apply:

    • .1 The web depth of lower bracket may be measured from the intersection of the sloped bulkhead of the hopper tank and the side shell plate, perpendicularly to the face plate of the lower bracket (see figure 3).

    • .2 Where stiffeners are fitted on the lower bracket plate, the web depth may be taken as the distance between the side shell and the stiffener, between the stiffeners or between the outermost stiffener and the face plate of the brackets, whichever is the greatest.

  • b) Tripping bracket alternative

    When tM is less than tREN,d/t at section b) of the side frames (see figure 2), tripping brackets in accordance with 2.3 may be fitted as an alternative to the requirements for the web depth to thickness ratio of side frames, in which case tREN,d/t may be disregarded in the determination of tREN in accordance with 2.1.2.

  • c) Immediately abaft collision bulkhead

    For the side frames located immediately abaft the collision bulkhead, whose scantlings are increased in order that their moment of inertia is such as to avoid undesirable flexibility of the side shell, when their web as built thickness tAB is greater than 1.65tREN,S, the thickness tREN,d/t may be taken as the value t'REN,d/t obtained from the following equation:

    where:
    tREN,S = is obtained from 3.3.

2.1.2.2 Thickness criteria based on shear strength check

 Where tM in the lower part of side frames, as defined in figure 1, is equal to, or less than, tCOAT, tREN,S shall be determined in accordance with 3.3.

2.1.2.3 Thickness of renewed webs of frames and lower brackets

 Where steel renewal is required, the renewed webs shall be of a thickness not less than tAB, 1.2tCOAT or 1.2tREN, whichever is the greatest.

2.1.2.4 Criteria for other measures

 When tREN < tM ≤ tCOAT, measures shall be taken, consisting of all the following:

  • .1 sand blasting, or equivalent, and coating (see 2.2);

  • .2 fitting tripping brackets (see 2.3), when the above condition occurs for any of the side frame zones A, B, C and D, shown in figure 1; and

  • .3 maintaining the coating in as new condition (i.e. without breakdown or rusting) at renewal and intermediate surveys.

The above measures may be waived if the structural members show no thickness diminution with respect to the as-built thicknesses and coating is in "as new" condition (i.e. without breakdown or rusting).

2.1.3 Criteria for frames and brackets (bending check)

 Where the length or depth of the lower bracket does not meet the requirements in annex 1, a bending strength check in accordance with 3.4 shall be carried out and renewals or reinforcements of frames and/or brackets effected as required therein.

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