Section 2-1 Rolled Steels

201. Application

The requirements in this Section apply to tests and inspection for the approval of manufacturing process of rolled steels (including rolled steel bars, to which Pt 2, Ch 1, Sec 6 of the Rules apply) as specified in Pt 2, Ch 1, Sec 3 of the Rules.

202. Data to be submitted

The following reference data in addition to those specified in 102. are Society.

(1) Kind of products (e.g. steel plate, shaped steel, etc.)

(2) Material grade (e.g. A, D, etc.) and range of thickness

(3) Aim material properties

(A) range of chemical composition and aim analyses, including grain and residual elements, for the various grades of steel; if the range depends on thickness and supply condition, the different ranges appropriate.

to be submitted to the

refining, micro alloying of chemical composition are to be specified, as

(B) Aim maximum carbon equivalent(Ceq.) according to Pt 2 of the Rules. For higher strength

grades with low carbon content C < 0,13 %, aim maximum

Pcm

content

(C) Production statistics of the chemical composition and mechanical properties (TS, YP, EL and

KV). The statistics are intended to demonstrate the capability to manufacture the steel prod- ucts in accordance with the requirements.

(4) Steelmaking

(A) Steel making process and capacity of furnaces or converters

(B) Raw material used

(C) Deoxidation and alloying practice

(D) Desulphurisation and vacuum degassing installation, if any

(E) Casting methods(ingot or continuous casting) : In the case of continuous casting, information relevant to type of casting machine, methods to prevent inclusions and segregation control

etc., is to be provided as appropriate.

(F) Ingot or slab

size and weight

(G) Ingot or slab treatment(scarfing and discarding procedures), etc

(5) Reheating and rolling

(A) Type of furnace and treatment parameters

(B) Rolling reduction ratio of slab/bloom/billet to finished product thickness

(C) Rolling and finishing temperatures

(D) Descaling treatment during rolling

(E) Capacity of the rolling stands

(6) Heat treatment

(A) Type of furnaces, heat treatment parameters and their relevant records

(B) Accuracy and calibration of temperature control devices

(7) For products delivered in the controlled rolling(CR) or thermo-mechanical rolling(TM) condition, the following additional information on the programmed rolling schedules is to be given:

(A) Description of the rolling process

(B) Normalizing temperature, re-crystallization temperature and used to determine them

Ar3

temperature and the methods

(C) Control standards for typical rolling parameters used for the different thickness and grades

of steel (temperature and thickness at the beginning and at the end of the passes, interval between passes, reduction ratio, temperature range and cooling speed of accelerated cooling,

if any) and relevant method of control

(D) Calibration of the control equipment

(8) Recommendations for working and welding in particular for products delivered in the CR or TM

condition

(A) Cold and hot working recommendations if needed in addition to the normal practice used in the shipyards and workshops

(B) Minimum and maximum heat input if different from the ones usually used in the shipyards and workshops (15 - 50 kJ/cm)

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

203. Approval tests

1. Test samples and specimen

(1) For each grade of steel and for each manufacturing process (e.g. steel making, casting, rolling and condition of supply), test samples are in general to be selected for each kind of product.

(2) Test samples are to be taken in the presence of the Surveyor from the product (plate, flat, sec- tion, bar) corresponding to the top of the ingot, or, in the case of continuous casting, a random

slabs from the ladle of the first heat and the last heat in one casting sequence.

(3) The position of the samples to be taken in the length of the rolled product, "piece" defined in Pt 2, Ch 1, 301. of the Rules (top and/or bottom of the piece) and the direction of the test specimens with respect to the final direction of rolling of the material are indicated in Table

2.2.2. The position of the samples in the width of the product is to be in compliance with Pt 2, Ch 1, 301. of the Rules

(4) Test samples are to be taken from the product with the maximum thickness (dimension) to be

approved. In addition, for initial approval, the Society will require selection of one test product of average thickness.

2. Approval test and acceptance criteria

(1) Approval tests are to be carried out in the presence of the Surveyor at the manufacturing plant and approval test items are to be as given in Table 2.2.1

(2) Test methods and acceptance criteria are to be as given in Table 2.2.2. However, where ac-

cordance with these requirements are difficult, decisions are left to the discretion of the Society.

3. Weldability test

(1) Preparation of the test assemblies

Welded joints tests are to be carried out on samples of the thickest plate.

(A) 1 butt weld test assembly welded with a heat input approximately 15 kJ/cm

(B) 1 butt weld test assembly welded with a heat input approximately 50 kJ/cm

(2) Welding of the test assemblies

(A) The butt weld test assemblies are to be prepared with the weld seam transverse to the plate rolling direction, so that impact specimens will result in the longitudinal direction.

(B) The bevel preparation should be preferably or .

(C) The welding procedure should be as far as possible in accordance with the normal welding practice used at the yards for the type of steel in question. The welding parameters includ- ing consumables designation and diameter, pre-heating temperatures, inter-pass temperatures, heat input, number of passes, etc. are to be reported.

(3) Type of tests and acceptance criteria

Kinds of tests, test methods and acceptance criteria are to be as given in Table 2.2.3.

(4) Other tests

Additional tests such as cold cracking tests (CTS, Cruciform, Implant, Tekken, Bead-on plate), CTOD, or other tests may be required in the case of when deemed necessary by the Society.

4. In addition to those specified in 105. 1 a reduction of the indicated number of casts, steel plate thicknesses and grades to be tested or complete suppression of the approval tests may be consid- ered subject to the approval by the Society on the basis of the preliminary information submitted by the manufacturer in case any of the following (1) or (5) is relevant. On the other hand, an in- crease of the number of casts and thicknesses to be tested may be required in the case of newly developed types of steel or manufacturing processes.

(1) Approval for any grade of steel also covers approval for any lower grade(impact test temper- ature) in the same strength level, provided that the method of manufacture and condition of supply are similar.

(2) For higher tensile steels, approval of one strength level covers the approval of the strength level immediately below, provided the steelmaking process, deoxidation and fine grain practice, casting method and condition of supply are similar.

(3) Change of the approval conditions.

(4) Grades of steel to be approved and availability of long term statistic results of chemical and mechanical properties

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

Table 2.2.1 Approval Test Items for Rolled Steels

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

Table 2.2.1 Approval Test Items for Rolled Steels (continued)

(7) Approval of manufacturing process of rolled bar for offshore chin is to comply with the following requirements.

(a) If a chain manufacturer wishes to use material from a number of suppliers, separate approval tests must be carried out for each supplier.

(b) Approval will be given only after successful approval of manufacturing process of testing of the completed chain. The approval will normally be limited to a thickness equal to that of the bars tested. up to the maximum diameter equal to that of the chain diameter tested. The rolling reduction ratio is to be recorded and is to be at least 5:1. The rolling reduction ratio used in production can be higher, but should not be lower than that qualified.

(c) A heat treatment sensitivity study simulating chain production conditions shall be applied in order to verify mechanical properties and establish limits for temperature and time combinations. All test details and results are to be submitted to the Society.

(d) The bar manufacturer is to provide evidence that the manufacturing process produces material that is resistant to strain ageing, temper embrittlement and all test details and results are to be submitted to the Society.

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

Table 2.2.2 Test Items and Selection of Test Specimens

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

Table 2.2.2 Test Items and Selection of Test Specimens (continued)

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

Table 2.2.2 Test Items and Selection of Test Specimens (continued)

(6) For plates made from hot rolled strip one additional tensile specimen is to be taken from the middle of the strip con- stituting the coil.

(7) Only for TMCP steels, or when deemed necessary by the Society.

(8) Not required for sections and plates having width less than 600 mm.

(9) For plates made from hot rolled strip one additional set of impact specimens is to be taken from the middle of the strip constituting the coil.

(10) For plates having thickness higher than 40 mm one additional set of impact specimens is to be taken with the axis lo- cated at mid-thickness.

(11) Impact test temperature of hull steels are as bellows ;

(12) Strain ageing charpy impact test temperature of hull steels are as bellows;

Table 2.2.3 Weldability test Items, test methods and acceptance criteria

Guidance for Approval of Manufacturing Process and Type Approval, Etc. 2015 13

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-1

5. In case of multi-source slabs or changing of slab manufacturer, the rolled steel manufacturer is re- quired to obtain the approval of the manufacturing process of rolled steels using the slabs from each slab manufacturer and to conduct approval tests in accordance with 2 and 3 above. A reduc- tion or complete suppression of the approval tests may considered by the Society taking into ac- count previous approval as follows:

(1) the rolled steel manufacturer has already been approved for the manufacturing process using oth- er semi finished products characterized by the same thickness, steel grade, grain refining and micro- alloying elements, steel making and casting process;

(2) the semi finished products manufacturer has been approved for the complete manufacturing proc- ess with the same conditions (steelmaking, casting, rolling and heat treatment) for the same steel

types.

204. Changes in the manufacturing process

In addition to those specified in 107., the manufacturer has to submit to the Society the documents together with the request of changing the approval conditions, in the case of the followings:

(1) Change of the manufacturing process (steel making, casting, rolling and heat treatment)

(2) Change of the maximum thickness (dimension)

(3) Change of

the chemical composition, added element, etc.

(4) Subcontracting the rolling and heat treatment, etc.

(5) Use of the slabs, blooms and billets manufactured by companies other than the ones verified in the approval tests.

205. Dealing after approval

Rolled steels which conform to the requirements in this Section are to be dealt with as [an ap- proved case] in the requirements in Pt 2, Ch 1, 201. 3 (2) of the Rules, unless otherwise specified by the Society. The manufacturer can detached the test samples from material without being stamp- ed by the Surveyor.

14 Guidance for Approval of Manufacturing Process and Type Approval, Etc. 2015

Ch 2 Approval of Manufacturing Process Ch 2, Sec 2-2