Section 3 Rolled Steels

301. Rolled steels for hull

1. Application

In application to 301. 1 (4) of the Rules, the term "the discretion of the Society" means the ac- ceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

2. Manufacturing process

(1) The term of "thermo-mechanical controlled processing(T M C P )" in 301. 3 of the Rules is defined in the following 2 of this Guidance.

(2) The carbon equivalent value of higher strength steels supplied in T M C P condition in Remarks

(13) to Table 2.1.6 of 301. 3 of the Rules is to comply with the requirements of Table 2.1.3

of the Guidance.

Table 2.1.3 Carbon Equivalent of Higher Strength Steels supplied in TMCP Condition

(3) The cold cracking susceptibility ( ) calculated by following a formula instead of carbon alent of previous (2) may be required to be submitted when deemed necessary by the Society.

3. Heat treatment

The definition of heat treatment mentioned in Remarks (1) to Table

301. 4 of the Rules are as follows : (Refer to Fig 2.1.2)

(1) As rolled, AR

2.1.8 and Table 2.1.9 of

This procedure involves the rolling of steel at high temperature followed by air cooling. The rolling and finishing temperatures are typically in the austenite recrystallization region and

above the normalising temperature. The strength and toughness properties of steel produced by this process are generally less than steel heat treated after rolling or than steel produced by ad- vanced processes.

(2) Normalising, N

Normalising involves heating rolled steel above the critical temperature, AC3, and in the lower end of the austenite recrystallization region followed by air cooling. The process improves the mechanical properties of as rolled steel by refining the grain size.

(3) Controlled Rolling(Normalising Rolling), CR(NR)

A rolling procedure in which the final deformation is carried out in the normalising temperature range, resulting in a material condition generally equivalent to that obtained by normalising.

(4) Quenching and Tempering, QT

Quenching involves a heat treatment process in which steel is heated to an appropriate temper- ature above the AC3 and then cooled with an appropriate coolant for the purpose of hardening the microstructure. Tempering subsequent to quenching is a process in which the steel is re-

heated to an appropriate temperature not higher than the improving the microstructure.

AC1 to restore toughness properties by

(5) Thermo-mechanical Rolling(Thermo-mechanical Controlled Processing), TM(TMCP)

This is a procedure which involves the strict control of both the steel temperature and the roll- ing reduction. Generally a high proportion of the rolling reduction is carried out close to the Ar3 temperature and may involve the rolling in the dual phase temperature region. Unlike con-

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trolled rolled (normalised rolling) the properties conferred by TM (T M C P ) cannot be reproduced by subsequent normalising or other heat treatment. The use of accelerated cooling on completion of TM-rolling may also be accepted subject to the special approval of the Society.

(6) Accelerated Cooling Processing, AcC

Accelerated cooling is a process, which aims to improve mechanical properties by controlled

cooling with rates higher than air cooling in the range of Ar3 temperature or below. However, direct quenching is excluded from accelerated cooling.

Fig 2.1.2 Rolled Processes for Rolled Steels for Hull

4. Selection of test samples

"Where specially approved by the Society" specified in 301. 6 (3) of the with as follows :

Rules may be dealt

(A) Impact tests for A H 32 and A H 36 may be dispensed with as far as periodical examinations

are carried out in the presence of the Society's Surveyor, except otherwise specially speci- fied on the approval of the manufacturing process.

(B) “Periodical” in (A) above means once a month. In

ried out for a set (3 pieces) of specimens and the compliance with the specifications.

(C) In case where the result does not comply with the

this case, impact tests specified are car-

results of which are to be confirmed in

specifications, retests for the lot of steel

material to which the failed specimens are belonging may be carried out in accordance with the requirements in 301. 10 of the Rules.

(D) Where the result of the retest does not comply with the requirements, impact tests provided

in Table 2.1.8 and 2.1.9 of 301. 6 of the Rules are to be carried out for all the steels manufactured thereafter. Where the test results during 6 months are confirmed as being sat- isfactory, the procedure specified in (B) above may be applied again.

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(E) Every manufacturer is to submit the annual report compiling the results of the impact to the Society.

5. Surface inspection and verification of dimensions

The application to 301. 8 of the Rules is to be in accordance with the follows :

(1) The Society may require the surface inspection of rolled steels to confirm in compliance the quality same as that of those days of approval of the manufacturing process.

(2) Criteria of surface inspection for flaw, pin hole and blow hole of steel plate is to comply

K S D 0208 (Method of macro-streak-flaw test for steel).

tests

with with

(3) Tolerance for rolled steel other than under thickness tolerance for plate is to comply with K S D

3051(Dimensions weight and permissible variations of hot rolled steel bar in coil), K S D

3052(Shape, dimensions, weight and tolerance of hot rolled steel flats), K S D 3500 (Dimensions

weight and permissible variations of hot rolled steel plates, sheets (Dimensions, weight and tolerances of hot rolled steel sections).

6. Quality and repair of defects

(1) Ultrasonic test procedures and acceptance criteria, specified in 301. be in accordance with either E N 10160 L evel S1/E 1, A ST M A 578 ard at the discretion of the Society.

and strips) and K S D 3502

9 (2) of the Rules, are to

Level C or accepted stand-

(2) The application to 301. 9 (3) of the Rules is to be in accordance with the followings:

(A) The surface defects may be removed by local grinding, in the presence of the Surveyor,

provided:

(a) the nominal product thickness will not be reduced by more than 7 % or 3 mm, whichever is the less

(b) each single ground area does not exceed 0,25 and all ground areas do not exceed 2 %

of the total surface in question.

(c) Ground areas lying opposite each other on both surfaces must not decrease the product

thickness

(d) Complete

trant test

by values exceeding the limits as stated above (a)

elimination of the defects may be verified by a magnetic particle or dye pene- procedure at the Surveyor's discretion.

(e) Where necessary, the entire surface may be ground to a depth as given by the under thick-

ness tolerances of the product. Ground areas lying in a distance less than their average breadth to each other are to be regarded as one single area.

(B) Local defects which cannot be repaired by grinding as stated above may be repaired with

the Surveyor's consent by chipping and/or grinding followed by welding subject to the fol- lowing conditions:

(a) Any single welded area shall not exceed 0,125 and the sum of all areas shall not ex- ceed 2 % of the surface side in question. The distance between two welded areas shall not

be less than their average width.

(b) The weld preparation must not reduce the thickness of the product below 80 % of the nominal thickness.

(c) the welding is to be carried out by an approved procedure, by the welder qualified by the Society, with approved electrodes, And the electrodes shall be of low hydrogen type and

must be dried in accordance with the manufacturer's requirements and protected against re- humidification before and during welding.

(d) All weldings are to be of reasonable length and must have at least 3 parallel welding

beads. Weld metal is to have at least 1.6 mm reinforcement, which is to be removed by grinding or chipping and grinding flush with the rolled surface, and is to present a work- manlike finish.

(e) The deposited metal must be sound without any lack of fusion, undercut, cracks and other defects which could impair the workability or use of the product. The finished products are to be presented to the Surveyor for acceptance. The soundness of the repair may be

verified by ultrasonic, magnetic particle or dye penetrant methods at the Surveyor's discretion.

(f) Products which are to be supplied in a heat treated condition are to be welded prior to the

heat treatment; otherwise, a new heat treatment may be required. Products supplied in the controlled rolled (C R ) or as rolled (A S) condition may require a suitable heat treatment af- ter welding. However, the post weld heat treatment may be omitted provided the manu-

facturer has demonstrated by a procedure test that the required properties will be main- tained without heat treatment.

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(g) For every welding repair the manufacturer must provide the Surveyor with a written report and a sketch showing sizes and location of the defects and full details of the repair proce- dure including the welding consumables, post weld heat treatment and non-destructive testing.

(C) Shapes may be conditioned by the manufacturer for the removal of surface defects in ac-

cordance with the following limitations.

(a) For material less than 9.5 mm thickness, in which the defects are not more than 0.8 mm in depth, the defects may be removed by grinding or chipping.

(b) For material 9.5 mm and over in thickness, in which the defects are not more than 1.6 mm in depth, the defects may be removed by grinding or chipping.

(c) Surface defects which are greater in depth than the limits shown above (a) and (b) may be removed by chipping or grinding and then depositing weld metal, in the presence of the Surveyor, subject to the following conditions.

(i) The total area of the chipped or ground surface of any piece is not to exceed 2 % of the total surface area of that piece.

(ii) After removal of any defect preparatory to welding, the thickness of the shape is not to be reduced by more than 30 % of the nominal thickness, nor is the depth of de- pression prior to welding to exceed 12.5 mm in any case.

(D) Before repair works prescribed in above (B) or (C) (c), the following documents are to be

submitted to the Society for approval.

(a) Specifications of repairing procedure which state about kind of surface defects, the way of chipping, grinding and welding, etc.

(b) Reports on results of tensile test, bend test, impact test, macro-structure inspection and hardness test on test samples repaired according to the procedure specified in above (a).

7. Forming

The cold deformation limit specified in 301. 12 of the Rules are to be dealt with as follows :

(1) For steels in structural members, the cold deformation rate shall be less than 10 %.(the inside bending radius shall not be less than 4.5 times the plate thickness)

(2) Where steels are subjected to the permanent deformation exceeding 10 %, an additional test may

be required by the Society.

(3) The use of hammering is not to be employed.

302. Rolled steel plates for boilers

1. Selection of test samples

In application to 302. 6 of the Rules, selections of test samples in case that where the purchasers carry out normalizing specified in 302. 3 (2) of the Rules at their factories are to comply with the following requirements :

(1) The manufacturer is to carry out normalizing of the test sample conforming to the requirements by the purchaser. Where no requirements have been given by the purchaser, the manufacturer may carry out normalizing as considered preferable. In this case, the manufacturer is to inform the purchaser the conditions of normalizing which had been carried out.

(2) The test samples is taken from the steel plates normalized at purchasers factory or normalized together with the steel plates simultaneously.

(3) The mechanical properties obtained by the test specimens specified in (1) and (2) above are to comply with the provisions in Table 2.1.12 of the Rules.

2. Marking

The markings related to the heat treatment of the steel plates provided in 302. 1 of the Rules are to be "TN " showing the case where normalizing is carried out for test samples only.

303. Rolled steel plates for pressure vessels

1. Selection of test samples

In application to 303. 6 of the Rules, selections of test samples in case that where the purchasers carry out normalizing specified in 303. 3 (2) of the Rules at their factories are to comply with the

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following requirements :

(1) The manufacturer is to carry out normalizing of the test sample conforming to the requirements by the purchaser. Where no requirements have been given by the purchaser, the manufacturer may carry out normalizing as considered preferable. In this case, the manufacturer is to inform the purchaser the conditions of normalizing which had been carried out.

(2) The test samples is taken from the steel plates normalized at purchasers factory or normalized together with the steel plates simultaneously.

(3) The mechanical properties obtained by the test specimens specified in (1) and (2) above are to comply with the provisions in Table 2.1.15 of the Rules.

2. In 303. 7 (2) of the Rules, the application to "deemed necessary by the Society" is to be in ac- cordance with the follows :

(1) Where the steel plates are used for spherical tanks or end plates, etc. of cylindrical tanks to contain cold liquefied gas at normal temperature, the impact test specimens are to be taken with their longitudinal axis normal (T direction) to the final direction of rolling.

(2) In previous (1), the specified values of the impact tests are to be in accordance with Table

2.1.15 of the Rules.

3. Marking

The markings related to heat treatments of the steel plates provided in 303. 1 of the Guidance are to be "TN " showing case where normalising is carried out for test samples only.

4. Chemical composition

In application to note (1) and (2), Table 2.1.14-1 of 303. 4 of the Rules, the term "deemed ap- propriate by the Society" means the acceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

304. Rolled steels for low temperature service

In application to 304. 1 (2) of the Rules, the term "the discretion of the Society" means the ac- ceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

305. Rolled stainless steels

1. Application

In application to 305. 1 (3) of the Rules, the grade, chemical composition and mechanical proper- ties of austenitic-ferritic stainless steel (hereinafter referred to as "duplex stainless steels") not ex- ceeding 75 mm in thickness are to be as specified on the followings.

(1) Grades and chemical composition

The grade and chemical composition of duplex stainless steels are to comply with the provisions in Table 2.1.4 of the Guidance.

Table 2.1.4 Grades and chemical composition

Chemical composition(%)

Grade

S31803 0.030

1.00

2.00

0.035

0.015

4.5 6.5 21.0 23.0 2.5 3.5 0.10 0.22

S32750

max.

max.

max.

max.

max.

6.0 8.0 24.0 26.0 3.0 4.5 0.24 0.35

(2) Mechanical properties

The mechanical properties of duplex stainless steels are to comply with the provisions in Table

2.1.5 of the Guidance.

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Table 2.1.5 Mechanical properties

2. Mechanical properties

In application to 305. 5 (1) of the Rules, the minimum yield strength specified in Table 2.1.20 of the Rules may be altered to other values subject to the approval of the Society. In this case, minimum yield strength and indication symbol of heat treatment specified in 301. 2 of the Guidance will be added after the steel grade mark.(eg. : R ST S 316L N - 400TM )

3. Forming

The deformation limit specified in 305. 10 of the Rules are to be dealt with as follows :

(1) For rolled stainless steels in structural members, the deformation rate shall be less than 20 %. (the inside bending radius shall not be less than 2 times the plate thickness)

4. "deemed necessary by the Society" referred in 305. 5 (3) of the Rules means where steels have properties with corrosion resistance or additional toughness.

306. Round bars for chain

Round bars for offshore mooring chain are to comply with Annex 2-9, 2 of this guidance.

307. Rolled steel bars for boiler

In application to 307. 3 of the Rules, the term "deemed appropriate by the Society" means the ac- ceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

308. High Strength Quenched and Tempered Steels for Welded Structures

1. Deoxidation practice and chemical composition

(1) In application to 308. 3 (3) of the Rules, the cold cracking susceptibility( ) for evaluating weldability is to be calculated from the ladle analysis in accordance with the formula specified in 301. 1 (3) of the Guidance.

(2) The maximum P cm for high strength quenched and tempered steels is to comply with the re- quirements of Table 2.1.6 of the Guidance.

Table 2.1.6 Grades and Cold Cracking Susceptibility

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2. In application to 308.

ceptance in accordance

1 (2) of the Rules, the term "the discretion of the with Pt 1, Ch 1, 104. or 105. of the Guidance.

Society" means the ac-

3. In application to note (1), Table 2.1.34 of 308. 5 of the Rules, the term the Society" means the acceptance in accordance with Pt 1, Ch 1, 104. or

"deemed appropriate by

105. of the Guidance.

309. Stainless clad steel plates

1. Mechanical properties

Shearing strength test method complies with K S D 0234.(Testing methods for

2. Quality and repair of defects

clad steel)

Ultrasonic test generally complies with K S D 3693 (Stainless-clad steel) and K S D 0234.(Testing methods for clad steel)

3. In application to 309. 2 (2) and 8 of the Rules, the term "the discretion of the Society" means the acceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

4. "deemed necessary by the Society" referred in 309. 5 (2) of the Rules means where plates have properties with corrosion resistance, etc.

310. Additional requirements for through thickness properties

1. Application

"deemed appropriate by the Society" referred in 310. 1 (2) of the Rules means where the other

steels than the material specified in 310. 1 (1) of the Rules ness properties.

2. Selection of test specimens

In application to 310. 5 (1) of the Rules, the term "round specimens are to be accepted in accordance with Pt 1, Ch 1,

3. Ultrasonic tests

are required improved through thick-

tensile test specimens" means where

104. or 105. of the Guidance.

(1) Ultrasonic test procedures and acceptance criteria, specified in 310. 7 (2) of the Rules, are to

be in accordance with either E N 10160 Level S1/E 1, ard at the discretion of the Society

A STM

A 578

Level C

or accepted stand-

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