october...rules and regulations for the construction and classification of steel ships rules change...

October 2016

Rules and Regulations for the Construction and

Classification of Steel Ships

Rules Change Notice No.1

October 2016

Rules and Regulations for the Construction and Classification

of Steel Ships

Rules Change Notice No.1

October 2016

Rules and Regulations for the Construction and Classification of Steel Ships Rules Change Notice No.1, October 2016 General Information This rule change notice gives the new additions and amendments to the ‘Rules and Regulations for the Construction and Classification of Steel Ships’ along with the effective dates from which these changes are applicable. These new additions and amendments are to be read in conjunction with the requirements given in the July, 2016 edition of the Rules. The Part / Chapters where amendments are made and their effective dates are indicated in TABLE 1. The actual requirements, arranged in the order of Part / Chapter / Section / Sub-section / Clause, have been given subsequently. For ease of reference, the newly added text has been highlighted by underlining and the deleted text by striking through.

Indian Register of Shipping

Rules and Regulations for the Construction and Classification of Steel Ships Rules Change Notice No.1, October 2016 Page 1 of 9

RULE CHANGE NOTICE No. 1– OCTOBER 2016

TABLE 1 – AMENDMENTS INCORPORATED IN THIS NOTICE These amendments will come into force as indicated in the Table

Section / Clause

Subject/Amendments

Part 1 Chapter 1 : General

The amendments are effective from 1 Oct 2016 Appendix 1 New notation “ BWE” and “BWT” added to the table Part 3 Chapter 6 :Bar Keel, Stem and Stern frame

The amendments are effective from 1 Oct 2016 4/4.4.3 Thickness requirement of insert plates based on shaft diameter is deleted. Part 3 Chapter 14 : Rudders

The amendments are effective from 1 Oct 2016 3/3.1.1 Definition of speed V is amended. Requirement for increasing the speed V for

calculation by using 1/3rd power law to cater to the MCR power of engine is deleted. 3/Table 3.1.1 Value of K2 for high lift rudders in ahead and astern condition is added. Part 5 Chapter 4 : Liquefied Gas Carriers

The amendments are applicable to Gas Carriers of which the keels are laid or which are at a similar stage of construction on or after 1 July 2016

4/IR 4.23.1.2.1 & IR 4.23.1.2.2

New clauses added providing requirements, for the carriage of products not covered by the IGC Code and this chapter.

4/IR 4.23.3.1 New clauses added providing permissible stresses in way of supports of type C Cargo tanks.

Part 6 Chapter 8 : Fire Safety Systems Code

The amendments are effective from 1 Oct 2016 5/IR 5.2.1.3.2 Clause amended to provide clarification on the requirements for pre-discharge alarm

for fixed gas fire extinguishing systems.



Part 1 - Chapter 1

General

Appendix 1 Table of characters of class and type notations of IRS, their expanded form and significance

Abbreviation Expanded Form Significance

Pollution Prevention Notations

Ballast Water Convention

BWE BALLAST WATER EXCHANGE

The additional class notation BWE is assigned to ships complying with the International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004, the relevant IMO and IRS Guidelines, and performing ballast water exchange.

BWT BALLAST WATER TREATMENT

The additional class notation BWT is assigned to ships complying with the International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004, the relevant IMO and IRS Guidelines, and fitted with a ballast water treatment system approved by an IMO Member State.



Part 3 - Chapter 6

Bar Keel, Stem and Sternframes

Section 4 : Stern Frames and Rudder Horns

4.4 Shaft brackets 4.4.3 Generally bracket arms are to be carried through the shell plating and attached to floors or girders of increased thickness. The shell plating in way of shaft brackets is to be increased in thickness to a minimum of 1.5 times the Rule bottom shell plating thickness

amidships. In way of struts, an insert plate is to be provided of thickness not less than: t = 1.9 √dts where dts is the tailshaft diameter. The connection of the struts to the shell plating is to be by full penetration welding.



Part 3 - Chapter 14

Rudders

Section 3 : Design Loads 3.1 Rudder force 3.1.1 The rudder force upon which rudder scantlings are to be based is to be determined from the following formula: Fr = 132 . K1 . K2 . K3 . A . V2 [N] where, Fr = rudder force [N] A = area of rudder blade [m2] V = maximum service speed (knots) with the ship on summer load waterline. Design speed, (knots) with vessel running ahead at maximum continuous rated shaft rpm and at the summer load waterline. Special consideration will be given to ships designed to operate at higher speed at a lower draft, and with full immersion of rudder. When the speed is less than 10 knots, V is to be replaced by the expression. Vmin = (V + 20)/3 For astern condition, the maximum astern speed is to be used, but in no case less than: Vastern = 0.5V Where the service speed is obtained at lower power than the maximum continuous rating of the propelling machinery, the speed V to be

used in the calculation is to be increased in proportion of (Power)1/3. K1 = factor based on the aspect ratio, λ of the rudder area; K1 = (λ + 2)/3; with λ not to be taken greater than 2. λ = b2/At; where b is the mean height of the rudder area [m] and At, the sum of rudder blade area and area of rudder post or rudder horn, if any, within the height b [m2] Mean breadth C [m] and mean height b [m] of rudder are calculated according to the co-ordinate system in Fig.3.1.1. K2 = Factor depending on type of the rudder and the rudder profile as per Table 3.1.1. K3 = 0.80 for rudders outside the propeller jet = 1.15 for rudders behind a fixed propeller nozzle = 1.0 otherwise. As per Fig, 3.1.1, 𝐶 = 𝑥2+𝑥3−𝑥1

2 ; Mean Breadth of Rudder

𝑏 = 𝑧3+𝑧4−𝑧22 ; Mean Height of Rudder



Table 3.1.1

Profile Type K2 Ahead condition Astern condition

NACA-00 series Göttingen

1.10 0.80

Flat side

1.10 0.90

Hollow

1.35 0.90

High lift rudders

1.70* To be specially considered ; if not known : 1.30

Fish tail

1.40 0.80

Single plate

1.00 1.00

Mixed profiles (e.g. HSVA)

1.21 0.90

Note : * In the case of flap rudder, K2 values determined by direct calculation methods taking into account geometry of rudder and flap and their angles of turn may be accepted as an alternative to the value indicated in the Table.



Part 5 - Chapter 4

Liquefied Gas Carriers

Section 4 : Cargo Containment

4.23 Type C independent tanks 4.23.1 Design basis 4.23.1.1 The design basis for type C independent tanks is based on pressure vessel criteria modified to include fracture mechanics and crack propagation criteria. The minimum design pressure defined in 4.23.1.2 is intended to ensure that the dynamic stress is sufficiently low, so that an initial surface flaw will not propagate more than half the thickness of the shell during the lifetime of the tank. 4.23.1.2 The design vapour pressure is not to be less than:

𝑃𝑜 = 0.2 + 𝐴𝐶(𝜌𝑟)1.5 [𝑀𝑃𝑎] Where:

𝐴 = 0.00185 �𝜎𝑚∆𝜎𝐴

�2

With: 𝜎𝑚=design primary membrane stress ∆𝜎𝐴=allowable dynamic membrane stress (double amplitude at probability level Q=10-8) and equal to :

- 55 [N/mm2 ] for ferritic-perlitic , martensitic and austenitic steel;

- 25 [N/mm2 ] for aluminium alloy (5083-O)

C = a characteristic tank dimension to be taken as the greatest of the following:

ℎ, 0.75𝑏 𝑜𝑟 0.45𝑙 with: h = height of tank (dimension ofin ship’s vertical direction) [m] b = width of tank (dimension ofin ship’s transverse direction) [m]

l = length of tank (dimension ofin ship’s longitudinal direction) [m] 𝜌𝑟=the relative density of the cargo (ρr=1 for fresh water) at the design temperature. When a specified design life of the tank is longer than 108 wave encounters, ∆𝜎𝐴 is to be modified to give equivalent crack propagation corresponding to the design life. IR 4.23.1.2.1 If the carriage of products not covered by the Chapter is intended, it is to be verified that the double amplitude of the primary membrane stress Δσm created by the maximum dynamic pressure differential ΔP does not exceed the allowable double amplitude of the dynamic membrane stress ΔσA as specified in 4.23.1.2

Δσm ≤ ΔσA

IR 4.23.1.2.2 The dynamic pressure differential ΔP is to be calculated as follows: 𝛥𝑃 = 𝜌

1.02×105�𝑎𝛽1𝑍𝛽1 − 𝑎𝛽2𝑍𝛽2�[MPa]

Where: ρ is maximum liquid cargo density in [kg/m3] at the design temperature 𝑎𝛽 ,𝑍𝛽 are as defined in 4.28.1.2 of this Chapter, see also Figure IR 4.23.1.2.2. 𝑎𝛽1 ,𝑍𝛽1 are the 𝑎𝛽 and 𝑍𝛽 values giving the maximum liquid pressure �𝑃𝑔𝑑�𝑚𝑎𝑥. 𝑎𝛽2 ,𝑍𝛽2 are the 𝑎𝛽 and 𝑍𝛽 values giving the minimum liquid pressure �𝑃𝑔𝑑�𝑚𝑖𝑛.

In order to evaluate the maximum pressure differential ΔP, pressure differentials are to be evaluated over the full range of the acceleration ellipse as shown in the Figure IR 4.23.1.2.2



The above mentioned procedure is only applicable to products having a relative density

exceeding 1 .

Fig :IR 4.23.1.2.2 Acceleration Ellipse and Internal pressure heads

4.23.3 Ultimate design condition 4.23.3.1 Plastic deformation 4.23.3.1.1 For type C independent tanks, the allowable stresses are not to exceed: 𝜎𝑚 ≤ 𝑓 𝜎𝐿 ≤ 1.5𝑓 𝜎𝑏 ≤ 1.5𝑓 𝜎𝐿 + 𝜎𝑏 ≤ 1.5𝑓 𝜎𝑚 + 𝜎𝑏 ≤ 1.5𝑓 𝜎𝑚 + 𝜎𝑏 + 𝜎𝑔 ≤ 3𝑓 𝜎𝐿 + 𝜎𝑏 + 𝜎𝑔 ≤ 3𝑓 Where: 𝜎𝑚 = equivalent primary general membrane stress; 𝜎𝐿 = equivalent primary local membrane stress; 𝜎𝑏 = equivalent primary bending stress; 𝜎𝑔 = equivalent secondary stress; 𝑓 = the lesser of (Rm/A) or (Re/B); with Rm and Re as defined in 4.18.1.3. With regard to the stresses σm, σL, σb and σg, the definition of stress categories in 4.28.3 are referred. The values A and B are to be shown

on the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk and is to have at least the following minimum values:

Nickel steels and

carbon manganese

steels

Austenitic steels

Aluminium alloys

A 3 3.5 4 B 1.5 1.5 1.5

IR 4.23.3.1 Permissible stresses in way of supports of type C Cargo tanks IR 4.23.3.1.1 The circumferential stresses at supports are to be calculated by a procedure acceptable to IRS for a sufficient number of load cases. IR 4.23.3.1.2 Permissible stresses in stiffening rings

.1 For horizontal cylindrical tanks made of C-Mn steel supported by saddles, the equivalent stress in the stiffening rings are not to exceed the following values if calculated using finite element method:

𝜎𝑒 ≤ 𝜎𝑎𝑙𝑙

Where:

β1

aβ2

β2

aβ1

β2

β1

Zβ1

Zβ1

β=β2

β=β1



𝜎𝑎𝑙𝑙 = 𝑚𝑖𝑛(0.57𝑅𝑚 ; 0.85𝑅𝑒)

𝜎𝑒 = �(𝜎𝑛 + 𝜎𝑏)2 + 3𝜏2 𝜎𝑒=von Mises equivalent stress in [N/mm2] 𝜎𝑛=normal stress in [N/mm2] in the circumferential direction of the stiffening ring 𝜎𝑏=bending stress in [N/mm2] in the circumferential direction of the stiffening ring 𝜏=shear stress in [N/mm2] in the stiffening ring

𝑅𝑚 and 𝑅𝑒 as defined in 4.18.1.3

Equivalent stress value 𝜎𝑒 is to be calculated over the full extent of the stiffening ring by a procedure acceptable to IRS

IR 4.23.3.1.3 Assumptions to be made for the stiffening rings

.1 The stiffening ring is to be considered as a circumferential beam formed by web, face plate, doubler plate, if any, and associated shell plating. The effective width of the associated plating is to be taken as: .1 For cylindrical shells:

an effective width [mm] not greater than 0.78 √𝑟𝑡 on each side of the web. A doubler plate, if any, may be included within that distance.

where: r = mean radius of the

cylindrical shell [mm] t = shell thickness [mm] .2 For longitudinal bulkheads (in

the case of lobe tanks): the effective width is to be

determined according to

established standards. A value of 20 tb on each side of the web may be taken as a guidance value.

where: tb = bulkhead thickness

(mm). .2 The stiffening ring is to be loaded with circumferential forces, on each side of the ring, due to the shear stress, determined by the bi-dimensional shear flow theory from the shear force of the tank.

IR 4.23.3.1.4 For calculation of reaction forces at the supports, the following factors are to be taken into account:

.1 Elasticity of support material (intermediate layer of wood or similar material). .2 Change in contact surface between tank and support, and of the relevant reactions, due to: – thermal shrinkage of tank. – elastic deformations of tank and support material. The final distribution of the reaction forces at the supports should not show any tensile forces.

IR 4.23.3.1.5 The buckling strength of the stiffening rings is to be examined. 4.23.3.2 Buckling criteria is to be as follows: the thickness and form of pressure vessels subject to external pressure and other loads causing compressive stresses are to be based on calculations using accepted pressure vessel buckling theory and are to adequately account for the difference in theoretical and actual buckling stress as a result of plate edge misalignment, ovality and deviation from true circular form over a specified arc or chord length.



Part 6 - Chapter 8

Fire Safety Systems Code

Section 5 : Fixed Gas Fire-Extinguishing Systems

5.2 Engineering specifications 5.2.1 General 5.2.1.3 System control requirements 5.2.1.3.2 Means are to be provided for automatically giving audible and visual warning of the release of fire extinguishing medium into any ro-ro spaces, container holds equipped with integral reefer containers, spaces accessible by doors or hatches and other spaces in which personnel normally work or to which they have access. The audible alarms are to be located so as to be audible throughout the protected space with all machinery operating and the alarms are to be capable of being distinguished from other audible alarms by adjustment of sound pressure or sound patterns. The pre-discharge alarm is to be automatically activated (e.g. by opening of the release cabinet door). The alarm is to operate for the length of time needed to evacuate the space, but not less than 20 [s], before the medium is released. Conventional cargo spaces and small spaces (such as compressor rooms, paint lockers, etc.) with only a local release need not be provided with such alarm. IR5.2.1.3.2 a) Reference is made to the Code on alerts and Indicators (AI Code), 1995 (Resolution A.1021(26)). The pre-discharge

alarms may be pneumatically (by the extinguishing medium or by air) or electrically operated, with requirements as follows:

• If electrically operated, the alarms are to be supplied with power from the main and an emergency source of power.

• If pneumatically operated by air, the air supplied is to be dry and clean and the supply reservoir is to be fitted with a low pressure alarm. The air supply may be taken from the starting air receivers. Any stop valve fitted in the air supply line is to be locked or sealed in the open position. Any electrical components associated with the pneumatic system are to be powered from the main and an emergency source of electrical power.

IR5.2.1.3.2 b) Conventional cargo spaces means cargo spaces other than ro-ro spaces or container holds equipped with integral reefer containers, and they need not be provided with means for automatically giving audible and visual warning of the release. IR5.2.1.3.2 c) The requirements mentioned in 5.2.2.2 are also applicable for the spaces mentioned in 5.2.1.3.2.

End of Chapter


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