Evaluation of Scantlings of Corrugated Transverse Watertight Bulkheads in Non-CSR Bulk Carriers Considering Hold Flooding

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1 (1997) (Rev ) (Rev.1.1 Mar 1998 /Corr.1) (Rev. Sept 000) (Rev.3 eb 001) (Rev.4 Nov 001) (Rev.5 July 003) (Rev.6 July 004) (Rev.7 eb 006) (Corr.1 Oct 009) (Rev.8 May 010) (Rev.9 Apr 014) Evaluation o Scantlings o Corrugated Transverse Watertight Bulkheads in Non-CSR Bulk Carriers Considering Hold looding.1 - Application and deinitions Revision 7 or subsequent revisions or corrigenda as applicable o this UR is to be applied to non-csr bulk carriers o 150 m in length and upwards, intending to carry solid bulk cargoes having a density o 1.0 t/m 3 or above, with vertically corrugated transverse watertight bulkheads, and with, a) Single side skin construction, or b) Double side skin construction in which any part o longitudinal bulkhead is located within B/5 or 11.5 m, whichever is less, inboard rom the ship s side at right angle to the centreline at the assigned summer load line in accordance with Note. The net thickness t net is the thickness obtained by applying the strength criteria given in.4. The required thickness is obtained by adding the corrosion addition t s, given in.6, to the net thickness t net. In this requirement, homogeneous loading condition means a loading condition in which the ratio between the highest and the lowest illing ratio, evaluated or each hold, does not exceed 1.0, to be corrected or dierent cargo densities. This UR does not apply to CSR Bulk Carriers.. - Load model..1 - General The loads to be considered as acting on the bulkheads are those given by the combination o the cargo loads with those induced by the looding o one hold adjacent to the bulkhead under examination. In any case, the pressure due to the looding water alone is to be considered. Notes: 1. The contracted or construction date means the date on which the contract to build the vessel is signed between the prospective owner and the shipbuilder. or urther details regarding the date o contract or construction, reer to IACS Procedural Requirement (PR) No. 9.. Revision 7 or subsequent revisions or corrigenda as applicable o this UR is to be applied by IACS Societies to ships contracted or construction on or ater 1 July 006. Page 1 o 18 IACS Req. 1997/Rev.9 014

2 The most severe combinations o cargo induced loads and looding loads are to be used or the check o the scantlings o each bulkhead, depending on the loading conditions included in the loading manual: - homogeneous loading conditions; - non homogeneous loading conditions; considering the individual looding o both loaded and empty holds. The speciied design load limits or the cargo holds are to be represented by loading conditions deined by the Designer in the loading manual. Non homogeneous part loading conditions associated with multiport loading and unloading operations or homogeneous loading conditions need not to be considered according to these requirements. Holds carrying packed cargoes are to be considered as empty holds or this application. Unless the ship is intended to carry, in non homogeneous conditions, only iron ore or cargo having bulk density equal or greater than 1.78 t/m 3, the maximum mass o cargo which may be carried in the hold shall also be considered to ill that hold up to the upper deck level at centreline... - Bulkhead corrugation looding head The looding head h (see igure 1) is the distance, in m, measured vertically with the ship in the upright position, rom the calculation point to a level located at a distance d, in m, rom the baseline equal to: a) in general: - D or the oremost transverse corrugated bulkhead - 0.9D or the other bulkheads Where the ship is to carry cargoes having bulk density less than 1.78 t/m 3 in non homogeneous loading conditions, the ollowing values can be assumed: D or the oremost transverse corrugated bulkhead D or the other bulkheads b) or ships less than 50,000 tonnes deadweight with Type B reeboard: D or the oremost transverse corrugated bulkhead D or the other bulkheads Where the ship is to carry cargoes having bulk density less than 1.78 t/m 3 in non homogeneous loading conditions, the ollowing values can be assumed: - 0.9D or the oremost transverse corrugated bulkhead - 0.8D or the other bulkheads Page o 18 IACS Req. 1997/Rev.9 014

3 D being the distance, in m, rom the baseline to the reeboard deck at side amidship (see igure 1) Pressure in the non-looded bulk cargo loaded holds At each point o the bulkhead, the pressure p c, in kn/m, is given by: p ρ gh tan c 1 c = ρ c = bulk cargo density, in t/m 3 γ g = 9.81 m/s, gravity acceleration h 1 = vertical distance, in m, rom the calculation point to horizontal plane corresponding to the level height o the cargo (see igure 1), located at a distance d 1, in m, rom the baseline. γ φ = 45 - (φ/) = angle o repose o the cargo, in degrees, that may generally be taken as 35 or iron ore and 5 or cement The orce c, in kn, acting on a corrugation is given by: c ( d h h ) 1 DB LS = ρcgs1 tan γ ρ c, g, d 1, γ = as given above s 1 = spacing o corrugations, in m (see igure a) h LS = mean height o the lower stool, in m, rom the inner bottom h DB = height o the double bottom, in m..4 - Pressure in the looded holds Bulk cargo holds Two cases are to be considered, depending on the values o d 1 and d. a) d d 1 At each point o the bulkhead located at a distance between d 1 and d rom the baseline, the pressure p c,, in kn/m, is given by: p c, = ρgh Page 3 o 18 IACS Req. 1997/Rev.9 014

4 ρ = sea water density, in t/m 3 g = as given in..3 h = looding head as deined in.. At each point o the bulkhead located at a distance lower than d 1 rom the baseline, the pressure p c,, in kn/m, is given by: [ ρ ρ( 1 perm) ] gh γ p, = ρgh + 1 tan c ρ, h = as given above c ρ c, g, h 1, γ = as given in..3 perm = permeability o cargo, to be taken as 0.3 or ore (corresponding bulk cargo density or iron ore may generally be taken as 3.0 t/m 3 ), coal cargoes and or cement (corresponding bulk cargo density or cement may generally be taken as 1.3 t/m 3 ) The orce c,, in kn, acting on a corrugation is given by: ( d d ) ρg( d d1) + ( pc, ) 1 le = s1 ρ g + DB LS c, 1 ( d h h ) ρ = as given above s 1, g, d 1, h DB, h LS = as given in..3 d = as given in.. (p c, ) le = pressure, in kn/m, at the lower end o the corrugation b) d < d 1 At each point o the bulkhead located at a distance between d and d 1 rom the baseline, the pressure p c,, in kn/m, is given by: p, ρcgh1 tan c = γ ρ c, g, h 1, γ = as given in..3 At each point o the bulkhead located at a distance lower than d rom the baseline, the pressure p c,, in kn/m, is given by: Page 4 o 18 IACS Req. 1997/Rev.9 014

5 [ ρ h ρ( 1 perm) h ] g γ p, = ρgh + 1 tan c c ρ, h, perm = as given in a) above ρ c, g, h 1, γ = as given in..3 The orce c,, in kn, acting on a corrugation is given by: c, ( d d ) ρcg( d1 d ) tan γ + ( pc, ) 1 le = s1 ρ cg tan γ + DB LS ( d h h ) s 1, ρ c, g, d 1,γ, h DB, h LS = as given in..3 d = as given in.. (p c, ) le = pressure, in kn/m, at the lower end o the corrugation Pressure in empty holds due to looding water alone At each point o the bulkhead, the hydrostatic pressure p induced by the looding head h is to be considered. The orce, in kn, acting on a corrugation is given by: = s ρ g 1 ( d h h ) DB LS s 1, g, h DB, h LS = as given in..3 ρ = as given in..4.1 a) d = as given in Resultant pressure and orce Homogeneous loading conditions At each point o the bulkhead structures, the resultant pressure p, in kn/m, to be considered or the scantlings o the bulkhead is given by: p = p c, 0. 8p c The resultant orce, in kn, acting on a corrugation is given by: = c, 0. 8 c Page 5 o 18 IACS Req. 1997/Rev.9 014

6 Non homogeneous loading conditions At each point o the bulkhead structures, the resultant pressure p, in kn/m, to be considered or the scantlings o the bulkhead is given by: p = p c, The resultant orce, in kn, acting on a corrugation is given by: = c,.3 - Bending moment and shear orce in the bulkhead corrugations The bending moment M and the shear orce Q in the bulkhead corrugations are obtained using the ormulae given in.3.1 and.3.. The M and Q values are to be used or the checks in Bending moment The design bending moment M, in knm, or the bulkhead corrugations is given by: M = 8 l = resultant orce, in kn, as given in..5 = span o the corrugation, in m, to be taken according to igures a and b.3. - Shear orce The shear orce Q, in kn, at the lower end o the bulkhead corrugations is given by: Q = 0. 8 = as given in Strength criteria General The ollowing criteria are applicable to transverse bulkheads with vertical corrugations (see igure ). or ships o 190 m o length and above, these bulkheads are to be itted with a lower stool, and generally with an upper stool below deck. or smaller ships, corrugations may extend rom inner bottom to deck; i the stool is itted, it is to comply with the requirements in.4.1. The corrugation angle φ shown in igure a is not to be less than 55. Requirements or local net plate thickness are given in.4.7. Page 6 o 18 IACS Req. 1997/Rev.9 014

7 In addition, the criteria as given in.4. and.4.5 are to be complied with. The thicknesses o the lower part o corrugations considered in the application o.4. and.4.3 are to be maintained or a distance rom the inner bottom (i no lower stool is itted) or the top o the lower stool not less than 0.15l. The thicknesses o the middle part o corrugations as considered in the application o.4. and.4.4 are to be maintained to a distance rom the deck (i no upper stool is itted) or the bottom o the upper stool not greater than 0.3l. The section modulus o the corrugation in the remaining upper part o the bulkhead is not to be less than 75% o that required or the middle part, corrected or dierent yield stresses. (a) - Lower stool The height o the lower stool is generally to be not less than 3 times the depth o the corrugations. The thickness and material o the stool top plate is not to be less than those required or the bulkhead plating above. The thickness and material o the upper portion o vertical or sloping stool side plating within the depth equal to the corrugation lange width rom the stool top is not to be less than the required lange plate thickness and material to meet the bulkhead stiness requirement at lower end o corrugation. The thickness o the stool side plating and the section modulus o the stool side stieners is not to be less than those required by each Society on the basis o the load model in.. The ends o stool side vertical stieners are to be attached to brackets at the upper and lower ends o the stool. The distance rom the edge o the stool top plate to the surace o the corrugation lange is to be in accordance with igure 5. The stool bottom is to be installed in line with double bottom loors and is to have a width not less than.5 times the mean depth o the corrugation. The stool is to be itted with diaphragms in line with the longitudinal double bottom girders or eective support o the corrugated bulkhead. Scallops in the brackets and diaphragms in way o the connections to the stool top plate are to be avoided. Where corrugations are cut at the lower stool, corrugated bulkhead plating is to be connected to the stool top plate by ull penetration welds. The stool side plating is to be connected to the stool top plate and the inner bottom plating by either ull penetration or deep penetration welds (see igure 6). The supporting loors are to be connected to the inner bottom by either ull penetration or deep penetration welds (see igure 6). (b) - Upper stool The upper stool, where itted, is to have a height generally between and 3 times the depth o corrugations. Rectangular stools are to have a height generally equal to times the depth o corrugations, measured rom the deck level and at hatch side girder. The upper stool is to be properly supported by girders or deep brackets between the adjacent hatch-end beams. The width o the stool bottom plate is generally to be the same as that o the lower stool top plate. The stool top o non rectangular stools is to have a width not less then times the depth o corrugations. The thickness and material o the stool bottom plate are to be the same as those o the bulkhead plating below. The thickness o the lower portion o stool side plating is not to be less than 80% o that required or the upper part o the bulkhead plating where the same material is used. The thickness o the stool side plating and the section modulus o the stool side stieners is not to be less than those required by each Society on the basis o the load model in.. The ends o stool side stieners are to be attached to brackets at upper and lower end o the stool. Diaphragms are to be itted inside the stool in line with and eectively attached to longitudinal deck girders extending to the hatch end Page 7 o 18 IACS Req. 1997/Rev.9 014

8 coaming girders or eective support o the corrugated bulkhead. Scallops in the brackets and diaphragms in way o the connection to the stool bottom plate are to be avoided. (c) - Alignment At deck, i no stool is itted, two transverse reinorced beams are to be itted in line with the corrugation langes. At bottom, i no stool is itted, the corrugation langes are to be in line with the supporting loors. Corrugated bulkhead plating is to be connected to the inner bottom plating by ull penetration welds. The plating o supporting loors is to be connected to the inner bottom by either ull penetration or deep penetration welds (see igure 6). The thickness and material properties o the supporting loors are to be at least equal to those provided or the corrugation langes. Moreover, the cut-outs or connections o the inner bottom longitudinals to double bottom loors are to be closed by collar plates. The supporting loors are to be connected to each other by suitably designed shear plates, as deemed appropriate by the Classiication Society. Stool side plating is to align with the corrugation langes and stool side vertical stieners and their brackets in lower stool are to align with the inner bottom longitudinals to provide appropriate load transmission between these stiening members. Stool side plating is not to be knuckled anywhere between the inner bottom plating and the stool top Bending capacity and shear stress τ The bending capacity is to comply with the ollowing relationship: 10 3 M 0.5Z le σ + Z σ a, le m a, m 0.95 M = bending moment, in knm, as given in.3.1 Z le = section modulus o one hal pitch corrugation, in cm 3, at the lower end o corrugations, to be calculated according to.4.3. Z m = section modulus o one hal pitch corrugation, in cm 3, at the mid-span o corrugations, to be calculated according to.4.4. σ a,le = allowable stress, in N/mm, as given in.4.5, or the lower end o corrugations σ a,m = allowable stress, in N/mm, as given in.4.5, or the mid-span o corrugations In no case Z m is to be taken greater than the lesser o 1.15Z le and 1.15Z le or calculation o the bending capacity, Z le being deined below. In case shedders plates are itted which: - are not knuckled; Page 8 o 18 IACS Req. 1997/Rev.9 014

9 - are welded to the corrugations and the top o the lower stool by one side penetration welds or equivalent; - are itted with a minimum slope o 45 and their lower edge is in line with the stool side plating; - have thicknesses not less than 75% o that provided by the corrugation lange; - and material properties at least equal to those provided by the langes. or gusset plates are itted which: - are in combination with shedder plates having thickness, material properties and welded connections in accordance with the above requirements; - have a height not less than hal o the lange width; - are itted in line with the stool side plating; - are generally welded to the top o the lower stool by ull penetration welds, and to the corrugations and shedder plates by one side penetration welds or equivalent. - have thickness and material properties at least equal to those provided or the langes. the section modulus Z le, in cm 3, is to be taken not larger than the value Z le, in cm 3, given by: Z' le = Z g + 10 Qh 3 g 0. 5 σ a g 1 h s p g Z g = section modulus o one hal pitch corrugation, in cm 3, o the corrugations calculated, according to.4.4, in way o the upper end o shedder or gusset plates, as applicable Q = shear orce, in kn, as given in.3. h g = height, in m, o shedders or gusset plates, as applicable (see igures 3a, 3b, 4a and 4b) s 1 = as given in..3 p g = resultant pressure, in kn/m, as deined in..5, calculated in way o the middle o the shedders or gusset plates, as applicable σ a = allowable stress, in N/mm, as given in.4.5. Stresses τ are obtained by dividing the shear orce Q by the shear area. The shear area is to be reduced in order to account or possible non-perpendicularity between the corrugation webs and langes. In general, the reduced shear area may be obtained by multiplying the web sectional area by (sin φ), φ being the angle between the web and the lange. When calculating the section modulus and the shear area, the net plate thicknesses are to be used. Page 9 o 18 IACS Req. 1997/Rev.9 014

10 The section modulus o corrugations are to be calculated on the basis o the ollowing requirements given in.4.3 and Section modulus at the lower end o corrugations The section modulus is to be calculated with the compression lange having an eective lange width, b e, not larger than as given in.4.6. I the corrugation webs are not supported by local brackets below the stool top (or below the inner bottom) in the lower part, the section modulus o the corrugations is to be calculated considering the corrugation webs 30% eective. a) Provided that eective shedder plates, as deined in.4., are itted (see igures 3a and 3b), when calculating the section modulus o corrugations at the lower end (cross-section in igures 3a and 3b), the area o lange plates, in cm, may be increased by: (.5a ) t t sh (not to be taken greater than.5at ) a = width, in m, o the corrugation lange (see igure a) t sh = net shedder plate thickness, in mm t = net lange thickness, in mm b) Provided that eective gusset plates, as deined in.4., are itted (see igures 4a and 4b), when calculating the section modulus o corrugations at the lower end (crosssection in igures 4a and 4b), the area o lange plates, in cm, may be increased by (7h g t ) h g = height o gusset plate in m, see igures 4a and 4b, not to be taken 10 greater than s gu 7 s gu = width o the gusset plates, in m t = net lange thickness, in mm, based on the as built condition. c) I the corrugation webs are welded to a sloping stool top plate which have an angle not less than 45º with the horizontal plane, the section modulus o the corrugations may be calculated considering the corrugation webs ully eective. In case eective gusset plates are itted, when calculating the section modulus o corrugations the area o lange plates may be increased as speciied in b) above. No credit can be given to shedder plates only. or angles less than 45º, the eectiveness o the web may be obtained by linear interporation between 30% or 0º and 100% or 45º. Page 10 o 18 IACS Req. 1997/Rev.9 014

11 Section modulus o corrugations at cross-sections other than the lower end The section modulus is to be calculated with the corrugation webs considered eective and the compression lange having an eective lange width, b e, not larger than as given in Allowable stress check The normal and shear stresses σ and τ are not to exceed the allowable values σ a and τ a, in N/mm, given by: σ a = σ τ a = 0.5 σ σ = the minimum upper yield stress, in N/mm, o the material Eective compression lange width and shear buckling check Eective width o the compression lange o corrugations The eective width b e, in m, o the corrugation lange is given by: b e = C e a C e = or β > 1.5 β β C e = 1.0 or β 1.5 β = 3 10 a t σ E t = net lange thickness, in mm a = width, in m, o the corrugation lange (see igure a) σ = minimum upper yield stress, in N/mm, o the material E = modulus o elasticity o the material, in N/mm, to be assumed equal to or steel Shear The buckling check is to be perormed or the web plates at the corrugation ends. The shear stress τ is not to exceed the critical value τ c, in N/mm obtained by the ollowing: τ τ c = τ E when τ E Page 11 o 18 IACS Req. 1997/Rev.9 014

12 τ τ τ 1 when τ E > 4τ = E σ τ = 3 σ = minimum upper yield stress, in N/mm, o the material t τ E = 0.9k t E (N/mm ) 1000c k t, E, t and c are given by: k t = 6.34 E t = modulus o elasticity o material as given in = net thickness, in mm, o corrugation web c = width, in m, o corrugation web (See igure a) Local net plate thickness The bulkhead local net plate thickness t, in mm, is given by: t = 14.9s w 1.05p σ s w = plate width, in m, to be taken equal to the width o the corrugation lange or web, whichever is the greater (see igure a) p = resultant pressure, in kn/m, as deined in..5, at the bottom o each strake o plating; in all cases, the net thickness o the lowest strake is to be determined using the resultant pressure at the top o the lower stool, or at the inner bottom, i no lower stool is itted or at the top o shedders, i shedder or gusset/shedder plates are itted. σ = minimum upper yield stress, in N/mm, o the material. or built-up corrugation bulkheads, when the thicknesses o the lange and web are dierent, the net thickness o the narrower plating is to be not less than t n, in mm, given by: t n = 14.9s n 1.05p σ s n being the width, in m, o the narrower plating. Page 1 o 18 IACS Req. 1997/Rev.9 014

13 The net thickness o the wider plating, in mm, is not to be taken less than the maximum o the ollowing t w and = 14.9s w 1.05p σ t w = w 440s 1.05p t σ np where t np actual net thickness o the narrower plating and not to be greater than 14.9s w 1.05p σ.5 - Local details As applicable, the design o local details is to comply with the Society requirements or the purpose o transerring the corrugated bulkhead orces and moments to the boundary structures, in particular to the double bottom and cross-deck structures. In particular, the thickness and stiening o eective gusset and shedder plates, as deined in.4.3, is to comply with the Society requirements, on the basis o the load model in.. Unless otherwise stated, weld connections and materials are to be dimensioned and selected in accordance with the Society requirements..6 - Corrosion addition and steel renewal The corrosion addition t s is to be taken equal to 3.5 mm. Steel renewal is required where the gauged thickness is less than t net mm. Where the gauged thickness is within the range t net mm and t net mm, coating (applied in accordance with the coating manuacturer s requirements) or annual gauging may be adopted as an alternative to steel renewal. Page 13 o 18 IACS Req. 1997/Rev.9 014

14 igure 1 Page 14 o 18 IACS Req. 1997/Rev.9 014

15 igure a Page 15 o 18 IACS Req. 1997/Rev.9 014

16 igure b Page 16 o 18 IACS Req. 1997/Rev.9 014

17 igure 3a Symmetric shedder plates igure 3b Asymmetric shedder plates igure 4a Symmetric gusset / shedder plates igure 4b Asymmetric gusset / shedder plates Page 17 o 18 IACS Req. 1997/Rev.9 014

18 igure 5 Permitted distance, d, rom edge o stool top plate to surace o corrugation lange igure 6 End o Document Page 18 o 18 IACS Req. 1997/Rev.9 014

S19 S19. (1997) (Rev ) (Rev. 2 Feb. 1998) (Rev.3 Jun. 1998) (Rev.4 Sept. 2000) (Rev.5 July 2004) S Application and definitions

S19 S19. (1997) (Rev ) (Rev. 2 Feb. 1998) (Rev.3 Jun. 1998) (Rev.4 Sept. 2000) (Rev.5 July 2004) S Application and definitions (1997) (Rev. 1 1997) (Rev. Feb. 1998) (Rev.3 Jun. 1998) (Rev.4 Sept. 000) (Rev.5 July 004) Evaluation of Scantlings of the Transverse Watertight Corrugated Bulkhead between Cargo Holds Nos. 1 and, with