Iranian Classification Society Rules

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Section 5 Platings


501. Definitions


1. yacht side is ranged as defined below :

(1) Upper bound : the upper deck, including long and short superstructure sides.

(2) Lower bound : the top of the bottom structure.

(3) Forward bound : the stem.

(4) Aft bound : the stern including transom.


2. The upper bound of the slamming area is at the turn of bilge or chine knuckles, and in cases no knuckles case, the upper bound shall be reached at 1.25 m above keel.


3. The definitions of symbols used in this chapter, unless specified otherwise, are to be in accordance with the following :

: thickness of plating (mm )

section modulus of stiffeners (cm )

: stiffener spacing measured along the plating (m )

basic stiffener spacing (m ), as defined

:


m


= 0.76 (m ), for watertight bulkheads, cargo hold bulkheads, superstructure and deckhouse

bulkheads

: stiffener span (m ) measured along the top flange of the member


or


: design pressure (kN m ) as defined in Ch 2.

: midship section modulus (cm ), as built at deck or bottom respectively

: midship section modulus (cm ), as defined in 401.

: correction factor for aspect ratio of plating field, see Table 3.3.1.


image


: radius of curvature (m )

: material factor in Table 3.3.2,

as


defined in Rules for Classification of Steel Ships, Pt 2,


Material notation

RA, RB, RD , RE

1.0

RA 32, RD 32, RE 32, RF 32

0.78

RA 36, RD 36 RE 36, RF 36

0.72

RA 40 RD 40, RE 40, RF 40

0.68

Table 3.3.1 Correction Factor Table 3.3.2 Material Factor ( )




1.0 =

0.72


0.4 < < 1.0


(1.1 - 0.25


= 0.4

1.0


502. Keel plating


1. The keel plating is to extend over the complete length of the craft. The breadth is not to be less than that obtained from the following formula :


mm


2. The thickness of keel plating is not to be less than the values according to the formula below. The thickness is, in no case, to be less than that of the adjacent bottom plating.


mm


is not to be taken less than 0.5 or greater than


503. Bottom and bilge plating


1. The thickness of bottom and bilge plating is not to be less than formula :


that obtained from the following


or


mm


The following extended formula for thickness of plating exposed when relevant.

to lateral pressure may be used




mm


and : as defined in

sea pressure or internal tank pressure, as defined in Ch 2, 304 or 305.

: static pressure equivalent to slamming, as defined in Ch 2, 301.

allowable stress, as defined in varied linearly.

Table 3.3.3. Between specified regions the s-value may be

image


Table 3.3.3 Allowable Stress (


Position

N mm


Within 0.4

120 for

160 for

0.1 from perpendicular

160


2. The thickness of bottom and bilge plating is not to be less than that obtained from the following formula :


min


is not to be taken less than 0.5 or greater than 1.0.


3. The thickness of bilge plating is not to be less than that of the adjacent bottom and side platings, whichever is the greater.


4. Plating in way of rudder bearings, shaft brackets, etc. may have to be increased to 2 times that of the adjacent platings.


504. Side plating


1. The thickness of side plating is not to be less than that obtained from the following formula :


or


mm


The following extended formula for thickness of plating exposed to lateral pressure when relevant.

may be used


or


mm


and : as defined in

:


as defined in 503. 1.

as defined in Ch 2, 302. or 303.

allowable stress, as defined in Table 3.3.4


2. The thickness of side plating is not to be less than formula defined in 503. 2.

image


Table 3.3.4 Allowable Stress of Side Plating


Position

N mm


Longitudinal Stiffening

Within

0.4

at

neutral axis

180

Within 0.4 at deck or bottom

- pressure ( )

- slamming pressure ( )


120

160

Within 0.1 from perpendiculars

180


Transverse Stiffening

Within

0.4

at

neutral

axis

160

Within 0.4 at deck or bottom

- pressure ( )

- slamming pressure ( )


60 max. 120

120 max. 160

Within 0.1 from perpendiculars

160

NOTE:

(1) Between specified regions the -value may be varied linearly.


505. Sheer strake at strength deck


1. The breadth of sheer strake is not to be less than that obtained from the following formula :


mm


2. The thickness of monohull yacht with L > 50 m is not to be less than that obtained from the fol- lowing formula :


mm


: required thickness of side plating, defined in 504.

: thickness of strength deck plating, defined in 506. is not to be taken less than .


3. If the end bulkhead of a superstructure is located within 0.5 amidships, the side plating should be given a smooth transition to the sheer strake below.

(1) The range for the sheer strake with increase thickness

m :

m : 2.5 m

(2) The increase thickness of sheer strake

m : (1 + 0.005 ) times of thickness, defined in previous Par

m : 1.3 times of thickness, defined in previous Par


506. Strength deck plating


1. The thickness of strength mula :


deck plating is not to be less than that obtained from the following for-


mm


: defined in Table 3.3.5 considering that deck position and

is not to be taken

image


Table 3.3.5 Minimum Thickness (

and Stiffener Spacing Ratio (


Deck



Unsheathed weather and cargo decks

5.0

1.0

Accommodation deck


4.5


0.5

Weather and cargo deck sheathed with wood or an approved composition


2. If the end bulkhead of a long superstructure is located within 0.5 amidship, the stringer

is to be increased in thickness for a length of bulkhead. The increase in thickness is to be 20 %.


3. If hatch opening corners of streamlined shape are strength deck at hatch corners is to be increased by

3 m on each side of the superstructure end


not adopted, the thickness of deck plating in 25 %.


507. Plating of deck below or above strength deck


1. The thickness of deck plating below or above strength deck is not mula, and the deep tank boundary deck plating is not to be less 508.


to be less than following for- than the thickness, defined in


mm


: defined in Table 3.3.6 considering that deck position and

is not to be taken


Table 3.3.6 Minimum Thickness (

and Stiffener Spacing Ratio (


Deck



Unsheathed weather and cargo decks


4.5


1.0

Accommodation deck

Weather and cargo deck sheathed with wood or an approved composition


4.0


0.5


508. Bulkhead plating


1. The thickness of bulkhead or tank boundary bulkhead is not to be less than that obtained from the following formula :


mm


The following extended formula for thickness of plating may be used when relevant.


mm

image


and : as defined in 501.

: design load, defined in Ch 2, 305.

: allowable stress, defined in Table


Table 3.3.7 Allowable Stresses of Bulkheads


Bulkheads and locations

N mm


Longitudinal bulkheads


Transverse stiffening


Within 0.4

Neutral axis

140

Deck or bottom

60 , max. 120

Within 0.1 from perpendiculars

160


Longitudinal stiffening


Within 0.4

Neutral axis

160

Deck or bottom

120

Within 0.1 from perpendiculars

160

Transverse bulkheads (tank and cargo hold bulkheads)

160

Collision bulkhead

160

Other watertight bulkheads

220

NOTE:

(1) Between specified regions the -value may be varied linearly.


2. The thickness of the tank boundary bulkhead is ing formula :

not to be less than that obtained from the follow-


mm


is not to be taken less than 0.5 or greater than 1.0.


3. The thickness of other bulkhead is not to be less than that obtained from the following formula.

However the thickness is not to be less than 3.0 mm .


mm


4. For platings in afterpeak bulkhead in way of sterntube, increased thickness or doubling may be required.


509. End bulkheads of superstructures and deckhouses, and exposed sides in deck- houses


1. The thickness of end bulkheads of superstructures and deckhouses and exposed sides in deckhouse bulkhead is not to be less than that obtained from the following formula :


mm


: design load, defined in Ch 2, 307.


image

2. The thickness of end bulkheads of superstructure and deckhouse is not to be less than that obtained from the following formula :

image


(1) For the lowest tier


mm


is not to be taken less than

(2) For higher tiers :

mm


is not to be taken less than 2.5


510. Machinery casings


The thickness of machinery casings protected by closed superstructure and deckhouse is not to be less than the following formula. However, thickness is not to be less than 4.0 mm .


(1) Machinery casings in cargo holds : mm

(2) Machinery casings in accommodation area :

mm


511. Bulwark plating


1. The thickness of bulwark


(1) The thickness of bulwark plating is not to be less than required for side plating in a super- structure in the same position if the height of the bulwarks is 1.8 m .

(2) If the height of bulwark is 1 m or less, the thickness need not be greater than that obtained form the following formula : mm

maximum : 6 mm , minimum : 3 mm

(3) For intermediate heights, the thickness of the bulwark may be found by interpolation.

2. Long bulwarks are to have expansion joints within 0.6 amidship.


3. Where bulwarks are on exposed decks form wells, ample provision is to be made for freeing the decks of water.

4. Bulwarks for ships with > 50 m are in general not to be welded to the top of the sheer strake within 0.6 amidship. Such weld connections may, however, be accepted upon special consid- eration of design, thickness and material grade.