Evaluation of Allowable Hold Loading of, Hold No. 1 with Cargo Hold No. 1 Flooded, for Existing Bulk Carriers

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1 (997) (Rev. 997) (Rev.2 ept. 2000) (Rev.3 July 2004) Evlution of Allowble Hold Loding of Crgo, Hold No. with Crgo Hold No. Flooded, for Existing Bulk Crriers. - Appliction nd definitions These requirements pply to ll bulk crriers of 50 m in length nd bove, in the foremost hold, intending to crry solid bulk crgoes hving density of,78 t/m 3, or bove, with single deck, topside tnks nd hopper tnks, (i) the foremost hold is bounded by the side shell only for ships which were contrcted for construction prior to July 998, nd hve not been constructed in complince with IAC Unified Requirement 20, (ii) the foremost hold is double side skin construction less thn 760 mm bredth mesured perpendiculr to the side shell in ships, the keels of which were lid, or which were t similr stge of construction, before July 999 nd hve not been constructed in complince with IAC Unified Requirement 20 (Rev. 2, ept. 2000). Erly completion of specil survey coming due fter July 998 to postpone complince is not llowed. The loding in crgo hold No. is not to exceed the llowble hold loding in the flooded condition, clculted s per.4, using the lods given in.2 nd the sher cpcity of the double bottom given in.3. In no cse, the llowble hold loding in flooding condition is to be tken greter thn the design hold loding in intct condition..2 - Lod model.2. - Generl The lods to be considered s cting on the double bottom of hold No. re those given by the externl se pressures nd the combintion of the crgo lods with those induced by the flooding of hold No.. The most severe combintions of crgo induced lods nd flooding lods re to be used, depending on the loding conditions included in the loding mnul: - homogeneous loding conditions; - non homogeneous loding conditions; - pcked crgo conditions (such s steel mill products). For ech loding condition, the mximum bulk crgo density to be crried is to be considered in clculting the llowble hold limit Inner bottom flooding hed The flooding hed h f (see Figure ) is the distnce, in m, mesured verticlly with the ship in the upright position, from the inner bottom to level locted t distnce d f, in m, from the bseline equl to: - D in generl - 0,95 D for ships less thn 50,000 tonnes dedweight with Type B freebord. D being the distnce, in m, from the bseline to the freebord deck t side midship (see Figure ). Note: Chnges introduced in Rev.2 re to be uniformly implemented by IAC Members nd Assoicites from July The contrcted for construction dte mens the dte on which the contrct to build the vessel is signed between the prospective owner nd the shipbuilder. For further detils regrding the dte of contrct for construction, refer to IAC Procedurl Requirement (PR) No IAC Req. 997/Rev

2 .3 - her cpcity of the double bottom of hold No. The sher cpcity C of the double bottom of hold No. is defined s the sum of the sher strength t ech end of: - ll floors djcent to both hoppers, less one hlf of the strength of the two floors djcent to ech stool, or trnsverse bulkhed if no stool is fitted (see Figure 2), - ll double bottom girders djcent to both stools, or trnsverse bulkheds if no stool is fitted. The strength of girders or floors which run out nd re not directly ttched to the boundry stool or hopper girder is to be evluted for the one end only. Note tht the floors nd girders to be considered re those inside the hold boundries formed by the hoppers nd stools (or trnsverse bulkheds if no stool is fitted). The hopper side girders nd the floors directly below the connection of the bulkhed stools (or trnsverse bulkheds if no stool is fitted) to the inner bottom re not to be included. When the geometry nd/or the structurl rrngement of the double bottom re such to mke the bove ssumptions indequte, to the ociety s discretion, the sher cpcity C of the double bottom is to be clculted ccording to the ociety s criteri. In clculting the sher strength, the net thicknesses of floors nd girders re to be used. The net thickness t net, in mm, is given by: t net = t - t c t t c = s built thickness, in mm, of floors nd girders = corrosion diminution, equl to 2 mm, in generl; lower vlue of tc my be dopted, provided tht mesures re tken, to the ociety s stisfction, to justify the ssumption mde Floor sher strength The floor sher strength in wy of the floor pnel djcent to hoppers f, in kn, nd the floor sher strength in wy of the openings in the outermost by (i.e. tht by which is closest to hopper) f2, in kn, re given by the following expressions: f 3 = 0 τ Af f2 3 τ = 0 Af,h 2 A f A f,h = sectionl re, in mm 2, of the floor pnel djcent to hoppers = net sectionl re, in mm 2, of the floor pnels in wy of the openings in the outermost by IAC Req. 997/Rev

3 (i.e. tht by which is closest to hopper) = llowble sher stress, in N/mm 2, to be tken equl to : σ F / 3 F = minimum upper yield stress, in N/mm 2, of the mteril =,0 2 =,20 2 my be reduced, t the ociety s discretion, down to,0 where pproprite reinforcements re fitted to the ociety s stisfction Girder sher strength The girder sher strength in wy of the girder pnel djcent to stools (or trnsverse bulkheds, if no stool is fitted) g, in kn, nd the girder sher strength in wy of the lrgest opening in the outermost by (i.e. tht by which is closest to stool, or trnsverse bulkhed, if no stool is fitted) g2, in kn, re given by the following expressions: g 3 τ = 0 Ag g2 3 τ = 0 Ag, h 2 A g A g,h = minimum sectionl re, in mm 2, of the girder pnel djcent to stools (or trnsverse bulkheds, if no stool is fitted) = net sectionl re, in mm 2, of the girder pnel in wy of the lrgest opening in the outermost by (i.e. tht by which is closest to stool, or trnsverse bulkhed, if no stool is fitted) = llowble sher stress, in N/mm 2, s given in.3. =,0 2 =,5 2 my be reduced, t the ociety s discretion, down to,0 where pproprite reinforcements re fitted to the ociety s stisfction.4 - Allowble hold loding The llowble hold loding W, in t, is given by: W = ρc V F F =,05 in generl,00 for steel mill products c = crgo density, in t/m 3 ; for bulk crgoes see.2.; for steel products, c is to be tken s the -3 IAC Req. 997/Rev

4 density of steel V = volume, in m 3, occupied by crgo t level h X h = ρ g c X = for bulk crgoes, the lesser of X nd X 2 given by X Z + ρ g ( E hf ) = ρ + ( perm ) ρ c X2 = Z + ρ g ( E h perm) f X = for steel products, X my be tken s X, using perm = 0 = se wter density, in t/m 3 g E d f, D h f perm = 9,8 m/s 2, grvity ccelertion = d f - 0, D = s given in.2.2 = flooding hed, in m, s defined in.2.2 = permebility of crgo, to be tken s 0,3 for ore (corresponding bulk crgo density for iron ore my generlly be tken s 3,0 t/m 3 ). Z = the lesser of Z nd Z2 given by: Z Z = C A h DB, h C A e = 2 DB, e C h = C e = sher cpcity of the double bottom, in kn, s defined in.3, considering, for ech floor, the lesser of the sher strengths f nd f2 (see.3.) nd, for ech girder, the lesser of the sher strengths g nd g2 (see.3.2) sher cpcity of the double bottom, in kn, s defined in.3, considering, for ech floor, the sher strength f (see.3.) nd, for ech girder, the lesser of the sher strengths g nd g2 (see.3.2) IAC Req. 997/Rev

5 n A = B DB, h i DB, i n ADB, e = i BDB s n i = number of floors between stools (or trnsverse bulkheds, if no stool is fitted) = spce of ith-floor, in m B DB,i =B DB - s B DB,i =B DB,h for floors whose sher strength is given by f (see.3.) for floors whose sher strength is given by f 2 (see.3.) B DB = bredth of double bottom, in m, between hoppers (see Figure 3) B DB,h = distnce, in m, between the two considered opening (see Figure 3) s = spcing, in m, of double bottom longitudinls djcent to hoppers -5 IAC Req. 997/Rev

6 Figure V = Volume of crgo -6 IAC Req. 997/Rev

7 Figure 2 Figure 3 END -7 IAC Req. 997/Rev