Section 3 Rolled Steels

301. Rolled steels for hull

1. Application

structural

(1) The requirements are to apply to hull structural rolled steels (hereinafter referred to as "steels") not exceeding 100 mm in thickness.

(2) These requirements also apply to normal and higher strength Corrosion Resistant Steels with all

grades up to 50 mm in thickness for steel plates, wide flats, sections and bars when such steel is used as the alternative means of corrosion protection for cargo oil tanks as specified in the performance standard MSC.289 (87) of Regulation 3-11, Part A-1, Chapter II-1 of the SOLAS

Convention (Corrosion protection of cargo oil tanks of crude oil tankers).

strength Corrosion Resistant steels as defined within this requirements, are

Normal and higher

steels whose corro-

sion resistance performance in the bottom or top of the internal cargo oil tank is tested and ap-

proved to satisfy the requirements in MSC.289 (87) in addition to other relevant requirements for hull structural steel, structural strength and construction.

(3) It is not intended that such steels be used for corrosion resistant applications in other areas of a

vessel that are outside of those specified in the performance standard MSC.289 (87) of Regulation 3-11, Part A-1, Chapter II-1 of the SOLAS Convention.

(4) Any requirement regarding steels over the thickness specified in Table 2.1.5 is to be left to the discretion of the Society. See Guidance

(5) Where improved through thickness properties are specified for plates and wide flats with thick- ness of 15 mm and over, the tensile test of through thickness property specified in 310. is to be carried out in addition to the requirements of 301.

(6) Steels other than those specified in 301. are to

2.

2. Kinds

Steels are classified as specified in Table 2.1.5.

be in accordance with the requirements of 101.

Table 2.1.5 Grades of Rolled Steels for hull

3. Manufacturing process

(1) Where steel plates are manufactured from the continuous casting slabs, the maximum thickness for approval is to be determined, as a rule, with the roll ratio of 6 as standard. However, upon consideration of the manufacturing process, the roll ratio may be reduced to 4 (3 for steel plate thickness in excess of 50 mm).

(2) The deoxidation practice and chemical composition of each grade are to comply with the re- quirements given in Table 2.1.6. For steel plates and wide flats over 50mm thick and When thermo-mechanical controlled processing (hereinafter referred to as "TMCP") is used as heat

treatment, slight deviations in the chemical composition may be allowed Society. See Guidance

4. Heat treatment

as approved by the

The heat treatment of each grade is to comply with the requirements given in Table 2.1.8 and

Table 2.1.9. See Guidance

Table 2.1.6 Deoxidation Practice and Chemical Composition

Table 2.1.7 Mechanical Properties

Table 2.1.8 Heat Treatment and Size of lot for Impact Test specimen for Normal Strength Steels

Table 2.1.9 Heat Treatment and Size of Lot for Impact Test Specimen for Higher Strength Steels

5. Mechanical properties

The mechanical properties of steels are to comply with the requirements given in Table 2.1.7.

6. Selection of test samples

(1) All material in a batch presented for acceptance tests is to be of the same product form e.g. plates, flats, sections, etc. from the same cast and in the same condition of supply. The test samples are to be fully representative of the material and, where appropriate, are not to be cut from the material until heat treatment has been completed.

(2) For the samples of steel from which tensile test specimens are cut, except where specially ap-

proved by the Society, steels not greater than 50 tonnes in mass (where the amount of scatter is to be less than 10 mm in thickness or diameter even when they belong to the same cast in

the same manufacturing process) are to be treated as one lot, and the largest one in thickness

or diameter is to be selected from each lot.

(3) For the samples of steel from which impact test specimens are cut, unless otherwise specially provided or except where specially approved by the Society, the thickest test sample is to be selected from each lot specified in Table 2.1.8 and Table 2.1.9, according to the substance of deoxidation practices, type of products and kind of heat treatments. See Guidance

(4) The test samples are to be taken from the following portions according to the requirements (a) to (c) below and Fig 2.1.4, unless otherwise specified:

(a) Plates and flat bars wider than 600 mm :

One end at a portion approximately 1/4 of the width from the flange end of the plates or flat bars.

(b)

(c)

Sections and flat bars not exceeding 600 mm in width:

One end at a portion approximately 1/3 of the width from the flange end. In case of channels, bulb plates and H-section, the test samples may be taken from the portion approx- imately 1/4 of the depth from the centre line of the web.

Bars:

The test samples are to be taken so that the axis of each test specimen may lie as near as possible to the portion specified in (i) and (ii) below. This rule, however, does not apply when, because dimensions of cross section are insufficient for standard test specimens, a piece cut in a proper length from the product having the largest diameter of a certain lot is used as it is for a tensile test.

(i) For non-circular sections, at approximately 1/6 of the largest distance from the outside.

(ii) For circular section, at approximately 1/6 of the diameter from the outside.

7. Selection of test specimens

(1) Test specimens are not to be heat treated separately from the product.

(2) Tensile test specimens are to be taken according to (a) to (c) below.

(a) One test specimen is to be taken from one test sample.

(b) The test specimens are to be taken with their longitudinal axis normal to the final direction

of rolling. For sections, bars and flat bars not exceeding 600 mm in width or when cially approved by the Society, however, they are to be taken with their longitudinal

parallel to the final direction of rolling.

spe- axis

(c) Flat test specimens of full product thickness are, generally, to be used. Round test specimen may be used when the plates and shapes(except bars) thickness exceeds 40 mm or for bars. When tensile test specimens of bar type are taken from plates and shapes except bars, they are to be taken at a portion approximately 1/4 of the thickness from the surface.

(3) Impact test specimens are to be taken according to (a) to (c) below.

(a)

(b)

(c)

A set of test specimens is to be taken from one test sample.

The test specimens are to be taken with their longitudinal axis parallel (L direction) to the final direction of rolling. When deemed necessary by the Society, however, they are to be taken with their longitudinal axis normal (T direction) to the final direction of rolling.

When the product thickness does not exceed 40 mm, the test specimens are to be cut with

their edge within 2 mm from the "as rolled" surface. When the product thickness exceeds 40 mm, the test specimen is to be taken at a portion where the axis of the test specimen cor- responds to approximately 1/4 of the thickness (1/6 of the diameter of bars) from the surface.

8. Surface inspection and verification of dimensions See Guidance

(1) Scope

(a) The Requirements apply to the tolerance on thickness of steel plates and wide flats with

widths of 600 mm or greater with thicknesses of 5 mm and over. The thickness tolerances for products below 5 mm may be specially agreed by the Society.

(b) Where Class C of ISO 7452 is applied in lieu of (a) above, the requirements in (4) and (5) below may not be applied. If Class C of ISO 7452 is to be used, the portion of the foot- note of ISO 7452, Table 2, which reads “Also a minus side of thickness of 0.3 mm is permitted.” is not to be applied.

(c)

(d)

Tolerances for length, width and flatness should be in accordance with a recognized national or international standard which specially agreed by the Society.

Tolerances for rolled steel other than plates and wide flats may be specially agreed.

(2) Responsibility

(a) The responsibility for verification and maintenance of the steel plates within the required tol- erances rests with the manufacturer. The Surveyor may require to witness some

measurements.

(b) The responsibility for storage and maintenance of the delivered steel plates with acceptable

level of surface conditions rests with the shipyard before the steel plates are used in fabrication.

(3)

(4)

(5)

Thickness tolerances

(a) The tolerances on thickness of a given steel plates are defined as:

(i) Minus tolerance is the lower limit of the acceptable range below the nominal thickness.

(ii) Plus tolerance is the upper limit of the acceptable range above the nominal thickness.

(iii) Nominal thickness is defined by the purchaser at the time of enquiry and order.

(b) The minus tolerance on thickness of products is 0.3 mm irrespective of nominal thickness.

(c) The plus tolerances on nominal thickness are to be in accordance with a recognized national

or international standard which specially agreed by the Society.

(d) The tolerances on nominal thickness are not applicable to areas repaired by grinding which are to be in accordance with the requirements in 301. 9. (3) of the Rules.

Average thickness

(a) The average thickness of steel plates or piece is defined as the arithmetic mean of the measurements made in accordance with the requirements in (5) below.

(b) The average thickness of steel plates or piece is not to be less than the nominal thickness.

Thickness measurements

(a) At least two lines among Line 1, Line 2 or Line 3 as shown in Fig. 2.1.4-1, are to be se- lected for the thickness measurements and at least three points on each selected line as shown in Fig. 2.1.4-1 are to be selected for thickness measurement. Automated method or manual method is applied to the thickness measurements.

(b) For automated methods, the measuring points at sides are to be located not less than 10

mm but not greater than 300 mm from the transverse or longitudinal edges

plates. For manual methods, the measuring points at sides are to be located not

of the steel

less than 10

mm but not greater than 100 mm from the transverse or longitudinal edges of the steel

plate.

Fig 2.1.4-1 Locations of Thickness Measuring Points

(c) If more than three points are taken on each line the number of points each line.

shall be equal on

(d)

Where the plate is to be later cut by the manufacturer as shown in Fig

urement locations to be same as the requirements in (a) thru (c) above.

2.1.4-2, the meas-

Fig 2.1.4-2 Locations of Thickness Measuring Points for Cut Steel Plates

(e) The procedure and the records of measurements are to be made available to and copies provided on request.

9. Quality and repair of defects

the Surveyor

(1) The quality of finished steel is to be in accordance with the requirements specified in 101. 1.

and 2. The steel is to be reasonably free from segregations and non-metallic inclusions.

(2) If plates and wide flats are ordered with ultrasonic inspection or required by the Society, the test procedure and acceptance criteria are to be made in accordance with an accepted standard at the discretion of the Society. However, the probe frequency is to be of 4MHz in general.

See Guidance

(3) The surface defects may be removed by local grinding. However, the procedure of removal of defect and repair is to be in accordance with the Guidance relating to the Rules specified by the Society. See Guidance

10. Retest Procedures

(1) Where the tensile test fails to meet the requirements, two further tensile tests may be made from the same piece. If both of these additional tests meet all of the requirements, the piece and the remaining pieces from the same lot may be accepted.

(2) If one or both of the additional tests referred to above are unsatisfactory, the piece from which

the above-mentioned test pieces have been taken is to be rejected. However, the remaining ma- terial from the same lot may be accepted, provided that two of the remaining pieces in the lot, selected in the same way, are tested with satisfactory results.

(3) (a) Where the result of the impact test is unsatisfactory, additional tests may be carried out, with the exception of the cases specified in (i) and (ii) below, by taking a set of test speci- mens out of the same piece from which the above-mentioned test specimens have been taken.

(i) The absorbed energy of all test specimens is under the required average absorbed energy.

(ii) The absorbed energy of two of the test specimens is under 70 % the required average absorbed energy.

(b) In case of the previous (a), all pieces of the same lot from which the test specimens have been taken, may be accepted, provided that the average absorbed energy of the six test specimens, including those which have been rejected as unsatisfactory, is not less than the required average absorbed energy, and that not more than two individual results are lower than the required average absorbed energy and of these, not more than one result is below 70 % of the required average absorbed energy.

(4) When the initial piece, representing a lot, gives unsatisfactory results from the additional Charpy

V-notch impact tests referred to the preceding (3), this piece is to be rejected but the remaining material in the lot may be accepted provided that two of the remaining pieces in the lot are tested with satisfactory results. If unsatisfactory results are obtained from either of these two pieces, then the lot of material is to be rejected. The pieces selected for these additional tests are to be the thickest remaining in the batch.

(5) If any test specimen fails because of faulty preparation, visible defects or (in the case of tensile test) because of fracturing outside the range permitted for the appropriate gauge length, the de- fective test piece may, at the Surveyors discretion, be disregarded and replayed by an additional test piece of the same type.

(6) Where the test pieces fail in the retests specified above, the piece from which the test pieces have been taken is to be rejected, However, at the consultation of the manufacturer and the or- derer, the remaining pieces in the lot may be resubmitted individually for test and those pieces which give satisfactory results may be accepted.

(7) At the consultation of the manufacturer and the order, the rejected piece may be resubmitted af- ter heat treatment of re-heat treatment, or may be resubmitted as any other grade of steel and then, may be accepted, provided that the required tests are satisfactory.

11. Marking

(1) Steels which have satisfactorily complied with the required tests are to be marked with the identification mark in accordance with the requirements in 110.

(2) Materials supplied in the thermo-mechanical controlled processing condition is to have the letters

TM added after the material grade mark. (e.g. E H 40TM )

(3) Steel plates that have complied with the requirements for corrosion resistant steel will be

marked with a designation by adding a corrosion designation to the unified identification mark for the grade of steel. And the corrosion resistant steel is to be designated according to its area of application as follows:

(a) Lower surface of strength deck and surrounding structures : RCU

(b) Upper surface of inner bottom plating and surrounding structures : RCB

(c) For both strength deck and inner bottom plating : RCW

(e.g. AH32 TM RCU Z35)

12. Forming

The cold deformation limit of hull structural rolled steels is to be in accordance with the Guidance specially specified by the Society. See Guidance

302. Rolled steel plates for boiler

1. Application

(1) These requirements are to apply to the steel plates (hereinafter referred to as "steel plates") for boilers and pressure vessels to be used at high temperatures.

(2) Steel plates other than those specified in 302. are to comply with the requirements in 101. 2.

2. Kinds The steel plates are classified as specified in Table 2.1.10.

Table 2.1.10 Grades of Steel Plates

3. Heat treatment

(1) For steel plates of the "R SP 42, R SP 46 and R SP 49" grade with 50 mm or less and of the "R SP 46A and R SP 49A " grade with 38 mm or less in thickness, they are to be as rolled. They, how- ever, may be heat treated(normalized or annealed for stress relieving) as deemed necessary by the manufacturer.

(2) For steel plates of the "R SP 42, R SP 46 and R SP 49" grade more than 50 mm and of the "R SP

46A

tain that

and R SP 49A " grade more than 38 mm in thickness, they are to be either normalized to ob- the normal grain size or heated uniformly to such a temperature at the time of hot forming an effect equivalent to normalizing can be achieved. In case of normalizing, it is, in prin-

ciple, to be performed by the manufacturer.

4. Chemical composition

The chemical composition of steel

2.1.11.

Table 2.1.11 Chemical Composition

plates is to comply with the requirements given in Table

5. Mechanical properties

The mechanical properties of steel plates are to comply with the requirements given in Table 2.1.12.

6. Selection and heat treatment of test samples See Guidance

(1) For the steel plates which are not to be heat treated, one test sample is to be taken from each plate as rolled directly from one slab or ingot

(2) For the steel plates which are to be heat treated, one test sample is to be taken from every similarly heat treated plate as rolled directly from one slab or ingot.

(3) For steel plates to which stress relieving is required after welding or stress relieving is applied

by the purchaser one or several times repeatedly during their working process, instruction of that effect is to be given at the time when they are placed for an order. In case where the pforor ctehdeurteesot f sastmrepslsesrebliyevhinegatiinsgntohtemspescliofiwedly bayndtheunpifuorrcmhalysert,o athheeattemtrpeeartmatuenret iosf t6o00be aptopli6ed5

0 , holding at that temperature for a period of over one hour per 25 mm of thickness, and

then, to be cooled to 300 in the furnace before exposure in a still atmosphere.

(4) The test samples are to be taken end of the plates.

Table 2.1.12 Mechanical Properties

from the portion approximately 1/4 of the width from the side

7. Selection of test specimens

Tensile test specimens are to be taken according to (1) to (3) below.

(1) One test specimen is to be taken from one test sample.

(2) The test specimens are to be taken with their longitudinal axis normal rolling.

to the final direction of

(3) The test specimens of bar type are to be taken from the portion approximately 1/4 of the thick-

ness from the surface.

8. Tolerance for thickness

Surface inspection and verification of dimensions are to be in accordance with the requirements in

301. 8. The minus tolerance for the nominal thickness of plates is to be 0.25 mm.

9. Retest procedure

Where the tensile tests from the first test specimens selected fail to meet the requirements, addi- tional tests may be conducted according to the requirements given in 109.

10. Marking

(1) Steel plates which have satisfactorily complied with the required tests are to be marked with the identification mark relating to heat treatment in addition to the requirements in 110.

(2) The marks relating to heat treatment are to be as specified in the following:

(a) Where the plates are normalized : N (e.g. : RSP 46N)

(b) Where the test specimens are normalized : TN (e.g. : RSP 46TN)

(c) Where the test specimens are heat treated corresponding to the stress relieving to be applied

: SR (e.g. : RSP 46N-SR, RSP 46TN-SR)

303. Rolled steel plates for pressure vessel

1. Application

(1) These requirements are mainly to apply to the steel plates for pressure vessels to be used at at- mospheric temperature (hereinafter referred to as "steel plates")

(2) The steel plates having characteristics differing from those specified in 303. are to comply with the requirements in 101. 2.

2. Kinds

The steel plates are classified as specified in Table 2.1.13.

Table 2.1.13 Grades of Steel Plates

3. Heat treatment

(1) RP V 24 plate is to be as rolled. The plates, however, may be normalized as deemed necessary by the Society.

(2) RP V 32 and RP V 36 plates are to be as rolled. The plates, however, may be normalized as

deemed necessary by the Society. But, they may be T M C P or quenched and tempered under the approval by the Society.

(3) RP V 42 plate is to be TM C P . The plate, however, may be normalized or quenched and tem- pered under the approval by the Society.

(4) RP V 46 and RP V 50 plates are to be quenched

the approval by the Society.

4. Chemical composition

and tempered. But, they may be TM CP under

(1) The chemical composition of

2.1.14.

Table 2.1.14 Chemical Composition

steel plates is to comply with the requirements given in Table

(2) Carbon equivalent(Ceq) and weld cold cracking susceptibility(Pcm) comply with the requirements given in Table 2.1.14-1.

Table 2.1.14-1 Carbon equivalent(Ceq) and Pcm value

value of steel plates are to

5. Mechanical properties

The mechanical properties of steel

2.1.15.

plates are to comply with the requirements given in Table

Table 2.1.15 Mechanical Properties

6. Selection of test samples See Guidance

(1) For the steel plates which are not to be heat treated, one test sample is to be taken from each plate as rolled directly from one slab or ingot.

(2) For the steel plates which are to be heat treated, one test sample is to be taken from every similarly heat treated plate as rolled directly from one slab or ingot.

(3) For steel plates to which stress relieving is required after welding or stress relieving is applied

by the purchaser, test samples are to be heat treated in accordance with the requirements in

302. 6 (3)

(4) The test samples are to be taken from the portion approximately 1/4 of the width from the side end of the plate.

7. Selection of test specimen

(1) Tensile test specimens are to be taken according to (a) to (c) below.

(a)

(b)

(c)

One test specimen is to be taken from one test sample.

The test specimens are to be taken with their longitudinal axis normal to the final direction of rolling .

The test specimens of bar type are to be taken from the portion approximately 1/4 of the thickness from the surface.

(2) Impact test specimens is to be taken according to (a) to (c) below. See Guidance

(a)

(b)

(c)

A set of test specimens are to be taken from one test sample.

The test specimens are to be taken with their longitudinal axis parallel (L direction) to the final direction of rolling. Where deemed necessary by the Society, however, they are to be taken with their longitudinal axis normal (T direction) to the final direction of rolling.

The test specimens are to be taken at a portion where the axis of the test specimen corre-

sponds to approximately 1/4 of the thickness from the surface.

8. Tolerance for thickness

Surface inspection and verification of dimensions are to be in accordance with the requirements in

301. 8. The minus tolerance for the nominal thickness of plates is to be 0.25 mm.

9. Retest procedures

Where the tensile test and impact tests from the first test specimen selected fails to meet the re- quirements, additional tests may be conducted according to the requirements given in 109.

10. Marking

(1) Steel plates which have satisfactorily complied with the required tests are to be marked with the identification mark relating to heat treatment in addition to the requirements in 110.

(2) The marks relating to heat treatment in (1) are to be as specified in the following:

(a) Where the plates are normalized : N (e.g. : R PV 32N)

(b) Where the plates are quenched and tempered : Q T (e.g. : R P V 46Q T)

(c) Where the plates are heat treated in TM CP condition : TM (e.g. : R P V 36TM )

(d) Where only test specimens are normalized in the steel plate as rolled) : TN (e.g. : R P V

32TN)

(e) Where the test specimens are heat treated corresponding to the stress relieving to be applied in the steel plate normalized : N SR (e.g. : R PV 32N SR)

11. Steel plates equivalent to standard

(1) The mild steel plates of grade R D and RE , the high tensile steels of rolled steels for hull speci- fied in 301. are taken as equivalent to the plates specified in 303. in case where the test specimens are taken as required in Pars 6 and 7 and test results comply with the requirements in 301. In this case, "P V " is to be suffixed to the markings to indicate the kind of plates specified in 301.

(2) Any requirements regarding heat treatment of steel plates specified in (1) is left to the dis- cretion of the Society.

304. Rolled steels for low temperature service

1. Application

(1) The requirements are to apply to the rolled steels not exceeding 40 mm in thickness intended

for tanks and ship's hull structures adjacent to tanks

such a hull structures of refrigerated cargo carrier (hereinafter referred to as "steels").

(2) Any requirement regarding the steels over 40 mm in Society. See Guidance

of liquefied gas carriers, and other parts which are exposed to low temperature

thickness is left to the discretion of the

(3) The requirements other than those specified in 304. are applicable to the requirements in 301.

(4) The steels other than those specified in 304. are

2. Kinds

Steels are classified as specified in Table 2.1.16.

Table 2.1.16 Grades and Chemical Composition

to comply with the requirements in 101. 2.

3. Heat treatment

The heat treatment of steels is to comply with the requirements given in Table 2.1.17.

Table 2.1.17 Heat Treatment

4. Deoxidation practice and chemical composition

(1) The deoxidation practice and chemical composition of each grade are to comply with the re- quirements given in Table 2.1.16. When deemed necessary, chemical elements other than those given in the table may be added.

(2) When heat treatment has been conducted according to T M C P , the chemical composition of steels specified in Table 2.1.16 may be modified subject to the approval by the Society.

5. Mechanical properties

The mechanical Where deemed additionally.

properties of steels are to comply with the requirements given in Table 2.1.17-1.

necessary by the Society. other tests on notch toughness may be required

Table 2.1.17-1 Mechanical properties

6. Selection of test sample

(1) For steel plates, one test sample is to be taken from each plate as rolled directly from one slab or ingot.

(2) For test samples used in other steels than steel plates, steels not greater than 10 tonnes in mass

(having the same cross-sectional dimensions and being from the same cast manufactured by the same process) are to be treated as one lot, and one test sample is to be taken from each lot.

(3) The requirements specified in 301. 6 (4) are to be applied to the selection of the test samples.

Table 2.1.18 Impact Test Temperature of Steels Specified in Pt 7, Ch 5.

7. Selection of test specimens

(1) Tensile test specimens are to be taken according to the requirements specified

(2) Impact test specimens are to be taken according to the following (a) and (b):

(a) The requirements specified in 301. 7 (3) are to apply.

in 301. 7 (2).

(b) For steel plates, the test specimens are to be taken with their longitudinal axis normal (T direction) to the final direction of rolling; for other steels than steel plates, they are to be

taken with their longitudinal axis parallel (L direction) to the final direction of rolling.

8. Surface inspection and verification of dimensions

Surface inspection and verification of dimensions are to be in accordance with the requirements in

301. 8. The minus tolerance for the nominal thickness of plates is to be 0.25 mm.

9. Retest procedures

Where the tensile test and impact tests from the first test specimen selected fails to meet the re- quirements, additional tests may be conducted according to the requirements given in 109.

10. Marking

Steels which have satisfactorily complied with the required tests are to be marked with the identi- fication mark in accordance with the requirements in 110. For steels to which the requirements given in Notes (1) of Table 2.1.17 and Notes (7) of Table 2.1.17-1 have been applied, "T M " and impact test temperature "T " are to be suffixed to the markings. (e.g. R L 33TM -50T )

305. Rolled stainless steels

1. Application

(1) These requirements are to apply to the rolled stainless steels (hereinafter referred to as "steels") for tanks in low temperature service or corrosion-resisting service.

(2) Austenitic-ferritic stainless steel (hereinafter referred to as "duplex stainless steels") not exceeding 75 mm in thickness are to be as in accordance with the Guidance relating to the Rules specified by the Society. See Guidance

(3) The requirements other than those specified in 305. are applicable to the requirements in

See Guidance

301.

(4) Steels other than those specified in 305. are to comply with the

2. Kinds

Steels are classified as specified in Table 2.1.19.

requirements in 101. 2.

Table 2.1.19 Grades and Chemical Composition of Stainless Steels

3. Heat treatment

The steels are generally to receive a solid solution treatment.

4. Chemical composition

The chemical composition of steels is to comply with the requirements

5. Mechanical properties

given in Table 2.1.19.

(1) The mechanical properties of steels are to comply with the requirements given in Table 2.1.20.

See Guidance

Table 2.1.20 Mechanical Properties of Stainless Steels

(2) The results of hardness test, according to the test method, given in Table 2.1.20.

(3) Other tests on notch toughness or corrosion resistance may by the Society. See Guidance

6. Selection of test samples

are to comply with the requirements be required, where deemed necessary

(1) One test sample is to be taken from every similarly heat treated plate as rolled directly from one slab or ingot.

(2) The requirements provided in 301. 6 (4) are to be applied to the selection of the test samples.

7. Selection of test specimens

(1) Tensile test specimens are to be taken according to the requirements specified in 301. 7 (2).

(2) The hardness test specimen may be a portion of tensile test specimen.

8. Tolerance for thickness

Surface inspection and verification of dimensions are to be in accordance with the requirements in

301. 8. The minus tolerance for the nominal thickness of plates is to be 0.25 mm.

9. Marking

Steels which have satisfactorily complied with the required tests are to be marked with identi- fication mark in accordance with the requirements in 110.

10. Forming

The cold deformation limit of the rolled stainless steels is to be in accordance with the Guidance specially specified by the Society.

306. Round bars for chain See Guidance

1. Application

(1) These

bars")

(2) Chain

requirements are to apply to the rolled round bars (hereinafter referred to as "Chain for chain specified in Pt 4, Ch 8, Sec 4.

bars for manufacture of offshore mooring chain are to be in accordance with the

Guidance relating to the Rules specified by the Society.

(3) The requirements other than those specified in 306. are applicable to the requirements in 301.

(4) Chain bars having characteristics differing from those specified in 306. are to comply with the

requirements in 101. 2.

2. Kinds

The chain bars are classified as specified in Table 2.1.21.

Table 2.1.21 Grades of Chain Bars

3. Deoxidation practice and chemical composition

The deoxidation practice and chemical composition of each grade are to comply with the require- ments given in Table 2.1.22. Elements other than specified in Table 2.1.22 may be added sub- ject to a special approval by the Society.

Table 2.1.22 Deoxidation Practice and Chemical Composition ( )

4. Heat treatment

Chain bars are to be as rolled condition.

5. Mechanical properties

The mechanical properties of chain bars are to comply with the requirements given in Table 2.1.23.

6. Selection of test sample

(1) Chain bars not greater than 50 tonnes in weight (from the same cast manufactured by process) are to be treated as one lot, and one test sample largest in diameter is to from each lot.

(2) Test sample mentioned in above (1), prior to sampling, must be subjected to the heat

the same be taken

treatment

provided for the finished chain cable. Details of the heat treatment must be indicated by the

chain cable manufacturer. In case of no indication, heat treatment of the test sample is to com-

ply with the requirements given in Pt.4, Sec.8 406. for each grade.

Table 2.1.23 Mechanical Properties

7. Selection of test specimens

(1) Test specimens are to be taken in accordance with the Table 2.1.24

Table 2.1.24 Number of test specimens

(2) The test specimens are to be taken with their longitudinal axis parallel to the final direction of rolling.

(3) The tensile and impact test specimens are to be taken from the test sample in the longitudinal direction at a depth of 1/6 diameter from the surface or as close as possible to this position.

(See Fig 2.1.5)

Fig 2.1.5 Selection of test specimens

(4) The longitudinal axis of the notch is to correspond approximately to the radial direction of each test specimen.

8. Surface inspection and verification of dimensions

(1) Surface inspection for all grades is to be carried out and it is to be confirmed that there are no harmful defects.

(2) The diameter and roundness of all grades of chain bars are to be within the tolerances specified

in Table 2.1.25.

Table 2.1.25 Dimensional tolerance

9. Retest procedures

(1) Where the tensile test and impact tests from the first test specimen selected fails to meet the requirements, additional tests may be conducted according to the requirements given in 109.

(2) If failure to pass the tensile test or impact test is definitely attributable to improper heat treat- ment of the test sample, a new test sample may be taken from the same piece and reheat

treated. The complete test (both tensile and impact test) is to be repeated; and the original re-

sults obtained may be disregarded.

10. Marking

Chain bars which have satisfactorily complied with the required tests are to be marked with identi- fication marks in accordance with the requirements in 110.

307. Rolled steel bars for boiler

1. Application

(1) These requirements are to apply to hot rolled steel bars intended to be used for the stay bolts for boilers (hereinafter referred to as "steel bars").

(2) The steel bars having characteristics differing from those specified in 307. are to comply with the requirements of 101. 2.

2. Kinds

The steel bars are classified as specified in Table 2.1.26.

Table 2.1.26 Grades and Chemical Composition

3. Heat treatment

The heat treatment of steel bars is to be as deemed appropriate by the Society. See Guidance

4. Chemical composition

The chemical composition of steel bars is to comply with the requirements given in Table 2.1.26.

5. Mechanical properties

The mechanical properties of steel bars are to comply with the following requirements.

(1) The tensile test of steel bars is to comply with the requirements given in Table 2.1.27.

Table 2.1.27 Mechanical Properties

(2) The bend test specimen is to stand being bent cold through 180 degrees without cracking on the outside of the bent portion to an inside radius given in Table 2.1.28.

Table 2.1.28 Bend Test

6. Selection of test samples

For the test samples of steel bars, steel bars which belong to the same cast manufactured by the same process and where the amount of scatter is to be less than 10 mm in diameter, are to be treated as one lot, and test samples are to be taken from each lot accord ing to the mass of the lot and to the requirements provided in Table 2.1.29.

Table 2.1.29 Number of Test Samples

7. Selection of test specimens

(1) Each one piece of tensile and bend test specimen is to be taken from one test sample.

(2) Test specimens are to be taken with their longitudinal axis parallel to the final direction of rolling.

(3) Tensile test specimens are to be taken from the sample in the longitudinal direction at a depth of 1/6 diameter from the surface or as close as possible to this position. (See Fig 2.1.5)

8. Tolerance for diameter

The tolerance for diameter of the steel bars is to comply with the requirements in Table 2.1.30.

Table 2.1.30 Tolerance for Diameter

9. Marking

Steel bars which have satisfactorily complied with the required tests are to be marked with the identification mark in accordance with the requirements in 110.

308. High Strength Quenched and Tempered Steels for Welded Structures

1. Application

(1) The requirements given in 308. are to apply to weldable high strength quenched and tempered steel plates and wide flats not exceeding 70 mm in thickness intended for mobile offshore units, tanks of liquefied gas carriers and process pressure vessels (hereinafter referred to as "steels")

(2) Any requirements regarding the steels over 70 mm in thickness are left to the discretion of the Society. See Guidance

(3) Product forms other than plates and wide flats, such as section and tubulars, may be provided to the requirements given in 308. when specially agreed to by the Society.

(4) Steels for hull structures should be in accordance with the Guidance specified by the Society.

(5) The requirements other than those specified in 308. are applicable to the requirements in 301.

(6) Steels having characteristics differing from those specified in 308. are to comply with the re- quirements in 101. 2.

2. Kinds

Steels are classified as specified in Table 2.1.31.

Table 2.1.31 Grade of Steels

3. Deoxidation practice and chemical composition

(1) The deoxidation practice and chemical composition of steels are to comply with the require- ments given in Table 2.1.32. Where deemed necessary, other elements than specified in Table

2.1.32 may be added.

(2) Where heat treatment has been conducted according to TMCP, the requirements given in Table

2.1.32 may be modified subject to the special approval by the Society.

(3) The cold cracking susceptibility(Pcm) for evaluating weldability should be in accordance with

the Guidance relating to the Rules specified by the Society. The maximum Pcm to be achieved is to be agreed with the Society and included in the approved specification. See Guidance

Table 2.1.32 Deoxidation Practice and Chemical Composition (%)

4. Heat treatment

The steels shall be in the quenched and tempered condition. Special consideration may be given to the supply of those steels in thicknesses up to 50 mm in the TMCP condition subject to approval of the Society.

5. Mechanical properties

(1) The mechanical properties of steels are to comply with the requirements given in Table 2.1.33.

(2) In the case of other product forms where longitudinal tests are agreed, the elongation values are to be 2 percentage units above those listed in Table 2.1.33.

(3) Where deemed necessary by the Society, other test on notch-toughness and weldability may be

required in addition to the tests specified in Table 2.1.33.

6. Selection of test samples

(1) One test sample is to be taken from every similarly heat treated plate as rolled directly from one slab or ingot.

(2) The requirements specified in 301. 6 (4) are to be applied to the selection of the test samples.

7. Selection of test specimens

(1) Tensile test specimens are to comply with the requirements shown in (a) to (c) below:

(a) Tensile test specimens are to be taken according to the requirements specified in 301. 7 (2).

(b) Normally flat tensile test specimens are to be prepared in such a manner as to maintain the rolling scale at least at one side.

(c) Where the thickness exceeds 40 mm, full thickness specimens may be prepared but when in- stead a machined round tensile test specimen is used then the axis must be located at a po-

sition lying at a distance of t/4 from the surface or as near as possible to this position.

Table 2.1.33 Heat Treatment and Mechanical Properties

Table 2.1.34 Impact Test Temperature for Steels specified in Pt 7, Ch 5

(2) Impact test specimens are to be taken according to the requirements specified in 304. 7 (2).

8. Surface inspection and verification of dimensions

(1) Surface inspection and verification of dimensions are to be in accordance with requirements specified in 301. 8.

(2) If required by the Society the manufacturer is to perform ultrasonic examinations in accordance with an approved standard.

(3) If required by the Society, through thickness tensile tests are to be performed in accordance

with requirements specified in 310.

9. Retest procedures

(1) Where the tensile test from the first test specimen selected fails to meet the requirements, addi- tional tests may be conducted according to the requirements given in 109. 1.

(2) Regarding the impact tests, additional tests are to be carried out according to the requirements given in 109. 2.

(3) For other product forms the impact tests are to be in the longitudinal direction, the results of

the tests are to comply with the appropriate requirements of Table 2.1.33

(4) Normally sub-surface test specimens will be taken, however, for material with a thickness in excess of 40 mm, impact tests should be taken at the quarter thickness (t/4) location.

10. Marking

Steels which have satisfactorily complied with the required tests are to be marked with the identi- fication mark in accordance with the requirements in 110. For steels to which the requirements given in Note (4) of Table 2.1.33 have been applied, the "impact test temperature T" are to be suffixed to the marking. (e.g. D H 63-25T)

309. Stainless clad steel plates

1. Application

(1) The requirements in 309. are to apply to the stainless clad steels not exceeding 50 mm in thickness intended for tanks of ships carrying dangerous chemicals in bulk, tank circumference hull construction units and corrosion-resisting tanks (hereinafter referred to as "steel plates").

(2) The requirements other than those specified in 309. are to be in accordance with the require- ments in 301.

(3) Steel plates over 50 mm in thickness and having characteristics differing from those specified in

309. are to comply with the requirements in 101. 2.

2. Process of manufacture

(1) Manufacture of steel plates is to comply with the processes shown in (a) to (e) below:

(a)

(b)

(c)

(d)

(e)

Rolling

Explosive pressing

Overlay rolling Cast rolling Explosive rolling

(2) Application of any other process of manufacture than those specified in (1) is left to the dis- cretion of the Society. See Guidance

3. Structural metals

(1) Base and clad materials for steel plates are to be mild steel plates of rolled steels for hull specified in 301. and steel plates of rolled stainless steels specified in 305., respectively. In case of overlay rolling or cast rolling, clad materials are to comply with the specified chemical composition of welding materials or stainless steel casting applied as a clad.

(2) The material grade marks are to be signified by a combination of base metal and clad material. (ex. A + R STS316)

4. Heat treatment

The steel plates are to comply with the requirements for heat treatment of the base

5. Mechanical properties See Guidance

(1) The mechanical properties of steel plates are to comply with the requirements

2.1.35.

metal.

given in Table

Table 2.1.35 Mechanical Properties

(2) Where deemed necessary by the Society according to the use of steel plates, tests on corrosion resistance may be required. See Guidance

6. Selection of test samples

(1) One test sample is to be taken from each steel plate, being from the same manufacturing proc- ess, which belong to the plate as rolled from a slab or ingot of a certain base metal. In case of overlay rolling, a separate test sample which is applied the same condition of manufacturing process can be made.

(2) The requirements specified in 301. 6 (4) are to be applied to the selection of the test samples.

7. Selection of test specimens

(1) Tensile test specimens are to be taken according to the requirements specified in 301. 7 (2).

(2) Impact test specimens are to be taken according to the requirements specified in 301. 7 (3).

In this case, the thickness of the test specimens is to agree with that of the base metal from which the clad material has been removed.

(3) Shearing strength test specimens are to be taken according to the requirements specified in the

following (a) to (b):

(a)

(b)

One test specimen is to be taken from one test sample.

The size and dimensions of the test specimens, are to be determined according to Fig 2.1.6.

Fig 2.1.6 Size and Dimensions of Shearing Test Specimens (unit: mm)

8. Surface inspection and verification of dimensions

The minus tolerance for the nominal thickness of plates is left to the discretion of the Society.

See Guidance

9 Quality and repair of defects See Guidance

(1) Each steel plate is to be subjected to ultrasonic testing. Any requirement for the test procedure is left to the discretion of the Society.

(2) Each cladding defects does not exceed 50 mm in length and 20 in area. All defect areas do not exceed 1.5 % of the total surface in question.

(3) Any cladding defects over the length and area of (2) may be repaired by welding in accordance with the requirements given in 301. 9 (3)

10. Marking

(1) The test certificates are to comply with the requirements given in 107. and are to contain the particulars as to the process of manufacture of steel plates and the thickness of the clad material.

(2) Steel plates which have satisfactorily complied with the required tests are to be suffixed with the following marks relating to the process of manufacture of the steel plates, in addition to the

marks showing

the kinds of the base and clad materials. (e.g.

A + RSTS 316 - R)

Rolling :

Cast rolling : Explosive pressing : Explosive rolling : Overlay rolling :

310. Additional requirements

1. Application

[-R]

[-ER]

[-B]

[-BR]

[-W R]

for through thickness properties

(1) The requirements in 310. are to apply to hull structural rolled steels and weldable high strength quenched and tempered steel plates and wide flats with thickness of 15 mm and over which is required improved through thickness properties to minimise the possibility of lamellar tearing during fabrication.

(2) The requirements are applicable to the other steels than the material specified in (1) above, where deemed appropriate by the Society. See Guidance

2. Through thickness properties

The through thickness properties of steels are to comply with the requirements given in Table

2.1.36 as the result of tensile tests whose specimens are taken in the through thickness direction of

the product.

Table 2.1.36 Through thickness properties

3. Deoxidation practice and chemical composition

In addition to the requirements of the appropriate steel specification given in 301. or 308., the maximum sulphur content is to be 0.008% determined by the ladle analysis.

4. Selection of test specimens

(1) For steel, of same thickness, belonging to the same charge and same heat treatment condition, one test sample is to be taken from each lot specified in Table 2.1.37.

Table 2.1.37 Batch size dependent on product and sulphur content

(2) The test samples are to be taken from one end (top of ingot when applicable) corresponding to the middle of the plates or flat bars as shown in Fig 2.1.7.

Fig 2.1.7 Selection of Test Samples

of the portion

5. Selection of test specimens

(1) Three round tensile test specimens are to be taken from one test sample in the through thick- ness direction.

(2) The test specimens are to be taken according to the requirements for dimensions provided in

Table 2.1.38.

Table 2.1.38 Dimensions of Specimen

(3) Where the product thickness does not allow to prepare specimens of sufficient length suitable for the gripping jaws of the testing machine, the ends of the specimens may be built up by suitable welding methods. The welding is not to impair the portion of the specimen within the parallel length.

6. Retest procedure

(1) Acceptance, rejection and retest criteria for the through thickness properties of steels are to comply with the requirements given in Fig 2.1.8

Fig 2.1.8 Acceptance, rejection and retest criteria for the through thickness properties of steels

(2) Fig 2.1.8 shows the three cases where a retest situation is permitted. In these instances three more tensile tests are to be taken from the remaining test sample or remaining steel plates of same piece. The average of all 6 tensile tests is to be greater than the required minimum aver- age with no greater than two results below the minimum average.