Part 2 Materials and welding Chapter 5 Special materials for naval ships

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1 RULES FOR CLASSIFICATION Naval vessels Edition December 2015 Part 2 Materials and welding Chapter 5 The content of this service document is the subject of intellectual property rights reserved by ("DNV GL"). The user accepts that it is prohibited by anyone else but DNV GL and/or its licensees to offer and/or perform classification, certification and/or verification services, including the issuance of certificates and/or declarations of conformity, wholly or partly, on the basis of and/or pursuant to this document whether free of charge or chargeable, without DNV GL's prior written consent. DNV GL is not responsible for the consequences arising from any use of this document by others. The electronic pdf version of this document, available free of charge from is the officially binding version.

2 FOREWORD DNV GL rules for classification contain procedural and technical requirements related to obtaining and retaining a class certificate. The rules represent all requirements adopted by the Society as basis for classification. December 2015 Any comments may be sent by to rules@dnvgl.com If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of DNV GL, then DNV GL shall pay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compensation shall never exceed USD 2 million. In this provision "DNV GL" shall mean, its direct and indirect owners as well as all its affiliates, subsidiaries, directors, officers, employees, agents and any other acting on behalf of DNV GL.

3 CURRENT CHANGES This is a new document. The rules enter into force 1 July Part 2 Chapter 5 Changes - current Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 3

4 CONTENTS Current changes...3 Section 1 General Scope Abbreviations Principles and test procedures... 6 Section 2 Steel plates, strips, sections and bars Liquid quenched and tempered structural steels Non-magnetizable steels...11 Section 3 Steel pipes Pipes of liquid quenched and tempered structural steels Pipes of non-magnetizable steels Part 2 Chapter 5 Contents Section 4 Forgings Forgings of liquid quenched and tempered structural steels Forgings of non-magnetizable steels Section 5 Steel castings Liquid quenched and tempered steel castings Non-magnetizable steel castings Section 6 Forgings of wrought copper alloys Scope Suitable wrought copper alloys Requirements to be met by manufacturers Surface finish Dimensions; dimensional and geometrical tolerances Requirements applicable to the material Testing Retesting Marking Certificates...39 Section 7 Titanium and titanium alloys Wrought titanium alloys Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 4

5 Section 8 Non-magnetizable anchor chain cables and accessories General Chain materials Construction and manufacture Testing of finished chain cables Marking Testing of accessories Section 9 Non-magnetizable anchors Scope Design and tests Materials for anchors and anchor components Testing Marking...51 Part 2 Chapter 5 Contents Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 5

6 SECTION 1 GENERAL 1 Scope These rules represent a supplement to RU SHIP Pt.2 The requirements mentioned therein shall be observed. 2 Abbreviations The following abbreviations are used in this chapter: AD AOD ASTM MIL-S SEW TRD VG VOD VODC WL Arbeitsgemeinschaft Druckbehälter (Working Group Pressure Vessels, Germany) Argon Oxygen Decarburization process American Society for Testing and Materials, Conshohocken, USA Military Specification, Department of Defence, USA Stahl Eisen Werkstoffblatt (Iron and Steel Material Specifications) Verlag Stahleisen GmbH, Postfach , D Düsseldorf Technische Regeln für Dampfkessel (Technical rules for Steam Boilers) Verteidigungsgeräte Norm (German Standard for Military Technology Systems) Vacuum Oxygen Decarburization process Vacuum Oxygen Decarburization (converter) process Werkstoff Leistungsblatt (Material Performance Sheet of VG Standard) Part 2 Chapter 5 Section 1 3 Principles and test procedures The requirements set out in RU SHIP Pt.2 Ch.1 and RU SHIP Pt.2 Ch.2 apply. In addition, the supplementary provisions given in [3.1] and [3.2] are also applicable. All materials delivered with VL or works (W) certificate shall be made at works approved by the Society for the type, grade and dimensions of material being supplied and for the relevant production and processing route, e.g. delivery condition. Rolling mills or forges without own steelmaking shall only use starting material supplied by works approved by the Society. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 6

7 3.1 Supplementary submarine test For materials that are used solely or in combination with other materials for the pressure hull in the construction of submarines, proof of suitability is required through the supplementary submarine test. By means of this test, it shall be verified that materials and their welds comply with the requirements in submarine construction, also with regard to the dynamic loads and the shock stresses which can arise during operation of a submarine. The test scope, the tests, the requirements and the test conditions will be specified by the Society for each individual case and must be observed accordingly. 3.2 Test of the permeability The relative permeability µ r in both the delivery condition and in the cold-formed state of the steel shall be determined using a volumetric measurement method (e.g. ASTM A 342) in accordance with VG To determine the influence of cold-forming on the relative permeability, the samples shall be finished in the intended delivery condition of the steel by stretching. In the case of non-magnetizable materials, the relative permeability µ r shall not exceed the value of Part 2 Chapter 5 Section 1 Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 7

8 SECTION 2 STEEL PLATES, STRIPS, SECTIONS AND BARS 1 Liquid quenched and tempered structural steels 1.1 Scope These rules are applicable to hot-rolled pressure hull and special plates up to a thickness of 150 mm, and to hot-formed or cold-formed bars and sections made of liquid quenched and tempered steels which are used for the construction of naval vessels and floating equipment. Rolled round bars intended for the manufacture of shafts, tie rods and bolts are subject to Sec.4 [1]. The application of these rules to products with larger thicknesses shall be specially agreed with the Society. Liquid quenched and tempered structural steels within the scope of these rules include the grades VL-M550 (15NiCrMo10-6, WL , HY-80), VL-M700 (16NiCrMo12-6, WL , HY-100) and VL-M900 (HY-130) as well as equivalent liquid quenched and tempered structural steels. Pressure hull plates are flat products for the construction of ships hulls and hull components that are subjected to diving pressure, and special plates (S) are flat products with limited excess weight. Steels which diverge from these rules, e.g. with regard to their nominal yield strength, their mechanical properties and their chemical composition, shall not be used without special approval from the Society. Part 2 Chapter 5 Section Approval The steels must be approved by the Society. For this purpose, the steel manufacturer shall send the Society a material specification containing the required information, such as chemical composition, manufacturing process, mechanical properties, condition of supply, as well as recommendations for welding, hot or cold forming, and heat treatment. Initial approval testing is required for the products mentioned in this section. The approval testing shall include weldability testing. 1.3 Requirements Steelmaking process The steels shall be manufactured in works approved by the Society using the AOD, VOD or VODC process, or using another process approved by the Society Chemical composition The chemical composition shall satisfy the requirements stated in the authorized specification and in Table 1. The limit values specified there apply to the melt analysis. Elements used for alloying and fine grain treatment shall be indicated in the manufacturer s specification. To assess weldability, sensitivity to cold cracking may be calculated from the ladle analysis according to the following formula: P cm = The maximum permitted value shall be agreed with the Society and must be indicated in the authorized specification Heat treatment The steels shall be supplied in the quenched and tempered condition. The minimum tempering temperature is 650 C for thicknesses up to 60 mm and 635 C for greater thicknesses for VL-M550. For VL-M700 it is 580 C and for VL-M900 the minimum tempering temperature shall be in accordance with the manufacturers specification. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 8

9 1.3.4 Mechanical properties The requirements applicable to the mechanical properties and the impact energy shall conform to the data in Table General characteristics of products Sec.2 [1.12.2] of DNV GL material rules applies in this regard. In addition, it should be noted that: procedures for repair welding and reporting thereon must be approved by the Society if defects are removed by grinding, the thickness remaining underneath the ground area shall be within the thickness tolerance Dimensions; dimensional and geometrical tolerances Sec.2 [1.12.3] to Sec.2 [1.12.6] of DNV GL material rules apply with the following addition: Table 1 Chemical composition of liquid quenched and tempered steels (ladle analysis) Brief name 15NiCr Mo10-6 DNV GL grade VL- M550 C Si Mn P S Cr Mo Ni As Cu Sb Sn Ti V Min ) Max Part 2 Chapter 5 Section 2 16NiCr Mo12-6 VL- M700 VL- M900 Min ) Max Min ) Max ) For vacuum-carbon deoxidization, Si min = 0.05% shall apply. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 9

10 Table 2 Mechanical and technological properties Grade Product shape 0.2% proof stress R p0.2 Yield strength ratio R p0.2 /R m Tensile strength R m Reduction in area Z Elongation A 5 [N/mm 2 ] [N/mm 2 ] [%] [%] VL-M550 VL-M700 Notched-bar impact bending test Test temp. [ C] [J] long. min. KV [J] trans. min. Plate Steel bar Section (l) 50 (q) (l) 18 (q) Plate Steel bar Section (l) 45 (q) (l) 16 (q) Part 2 Chapter 5 Section 2 VL-M900 Plate (l) in longitudinal direction (q) in transverse direction For the minus tolerance applicable to the nominal thickness of pressure hull plates, the data according to class C, and for special plates according to class A in Table 1 of EN (edition 2011) shall apply. In the case of special plates, the average thickness increase is additionally restricted by a limited maximum weight as per Table 6 of EN (edition 1991). 1.4 Testing Testing of chemical composition The manufacturer shall determine the composition of every heat and shall issue the relevant certificate Tensile testing From every piece heat-treated in a unit, at least one tensile test specimen shall be taken and tested. If plates are heat-treated by continuous processes, special arrangements may be made with regard to the number of tests required and the making of the test specimens. In the case of pressure hull plates, a tensile test specimen shall be taken for each rolled length. Test specimens shall be cut with their longitudinal axes transverse to the final direction of rolling, except in the case of sections and wide flats < 600 mm in width, where longitudinal test specimens shall be taken. For other product forms, the tensile test specimens may be taken in either the longitudinal or the transverse direction as agreed with the Society. Normally, flat tensile test specimens shall be used. The tensile-test specimens may be taken from the full or the half product thickness; however, one surface side of the product must be maintained. For thicknesses above 30 mm, round tensile test specimens may be used, the axis of which must lie at a distance of ¼ of the product thickness from the surface. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 10

11 1.4.3 Notched-bar impact bending test From every piece heat-treated in a unit, or from each rolling length in the case of pressure hull plates, at least one set of three Charpy V-notch impact test specimens in accordance with RU SHIP Pt.2 Ch.1 Sec.3 shall be taken and tested. For continuous heat-treated plates, special consideration may be given to the number and location of test specimens required. Unless otherwise accepted by the Society, the V-notch impact test specimens for plates and wide flats 600 mm shall be taken with their axes transverse to the main rolling direction. For other product forms, the impact tests shall be in the longitudinal direction. The specimens axes must be positioned at a distance of ¼ of the product thickness from the surface, or as near as possible to this position Through thickness tensile test If required by the Society, through thickness tensile tests shall be performed by using test specimens taken at right angles to the surface of the product in accordance with, RU SHIP Pt.2 Ch.2 Sec.2 [5] Inspection of surface and dimensions The manufacturer shall inspect the condition of the surface and the dimensions of the product and shall then present the products to the surveyor for inspection Ultrasonic examination If necessary for the envisaged use of the material, the manufacturer shall perform ultrasonic examinations in accordance with RU SHIP Pt.2 Ch.2 Sec.2 [1.12]. Part 2 Chapter 5 Section Retests If one of the tensile tests fails to meet the requirements, two additional test specimens shall be taken from the same position of the piece and subjected to the test. The piece will be accepted if both additional tests are satisfactory. When the average value of the impact test fails to meet the requirements or more than one value is below the required average value or when one value is below 70% of the specified average value, the procedure described in RU SHIP Pt.2 Ch.1 Sec.2 [3.7]. shall be followed. 1.5 Marking Every finished piece shall be clearly marked by the maker in at least one place with DNV GL s stamp and the following particulars: manufacturer's mark unified identification mark for the grade of steel (e.g. VL-M550) or manufacturer s trade name heat number, plate number or equivalent identification mark The entire set of markings shall be encircled with paint or otherwise highlighted so as to be easily recognized. 2 Non-magnetizable steels 2.1 Scope These rules are applicable to flat products, including pressure hull plates and special plates as well as sections and bars, made of non-magnetizable steels that are used for the construction of naval ships or floating equipment. Rolled round bars intended for the manufacture of shafts, arbors, pins and similar parts are subject to Sec.4 [2]. Pressure hull plates (DK) are flat products for the construction of ships hulls and hull components that are subjected to diving pressure, and special plates (S) are flat products with limited excess weight. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 11

12 2.2 Materials Non-magnetizable steels are steels according to SEW 390 or comparable grades with relative permeability µ r < In addition plates, strips, bars and sections as per VG and VG can be utilized in accordance with the following material performance sheets (WL); see Table 3 and Table 4: Table 3 Plates, strips and hollow sections WL Part Steel X2CrNiMnMoNNb X2CrNiMoN X2CrNiMoN X2CrNiMnMoNNb X2CrNiMnMoNNb Part 2 Chapter 5 Section 2 Table 4 Bars and sections WL Part Steel X2CrNiMnMoNNb X2CrNiMoN X2CrNiMoN X2CrNiMnMoNNb X2CrNiMnMoNNb Steels which are intended for carrying liquefied gases, or for which a special chemical stability in relation to the cargo or operating fluids is required, must additionally comply with the requirements set out in RU SHIP Pt.2 Ch.2 Sec.3 [3] and RU SHIP Pt.2 Ch.2 Sec.3 [4]. Initial approval testing is required for the products mentioned in this section. The approval testing shall include weldability testing. 2.3 Condition of supply and heat treatment All products shall be presented in the heat-treated condition appropriate to the material, i.e. the steels must be solution-annealed and quenched. The steel grade X5NiCrTiMoV26-15 (1.3980) must be additionally artificially aged at C. 2.4 Dimensional tolerances Unless stipulated otherwise in the order specification, plates shall be supplied in accordance with class B in Table 1 of EN (edition 2011), (permitted thickness tolerance 0.3 mm). For the minus tolerance applicable to the nominal thickness of pressure hull plates, the data according to class C and for special plates according to class A in Table 1 of EN (edition 2011) shall apply. In the case of special plates, the average thickness increase is additionally restricted by a limited maximum weight as per Table 6 of EN (edition 1991). For all other products, the values stated in the relevant standards shall apply. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 12

13 2.5 General condition of products The provisions of RU SHIP Pt.2 Ch.2 Sec.2 [1.12] shall apply. Surface defects may generally only be repaired by grinding. In doing so, the relevant minus tolerance must not be exceeded at any point. The rectification of surface defects by welding is not permissible. The edges of the cut plates and strips shall be free of cracks. For pressure hull plates, the permissible depth of rolled-in scale, depressions or other types of surface damage shall be limited to 0.20 mm, whereby the thickness at these points must not fall below the nominal thickness. Isolated depressions of up to 0.40 mm are permissible, provided that the thickness at these points does not fall below the nominal thickness and the sum of these flawed areas is not larger than 15% of the total area of one side of the plate. The defects exceeding 0.20 mm in depth must be remedied by grinding, whereby it must be ensured that the nominal thickness is maintained and the transitions are smooth. For the surface condition of cold-rolled products, the provisions set out in Iron and Steel Material Specification SEW 390 shall apply. 2.6 Requirements applicable to material properties Chemical composition The limit values for the chemical composition stated in the standards or in the specifications approved by the Society shall apply. For welded structures which cannot be heat treated after welding and for which resistance to intercrystalline corrosion is required, only stabilized austenitic steels or steels with carbon contents of C 0.03% shall be used. Part 2 Chapter 5 Section Mechanical properties The requirements applicable to the mechanical properties which are stated in the recognized standard or the approved material specification shall be verified during testing. If not defined in a different way the minimum value of the 0.2% compression yield point shall be equivalent to the value of the 0.2% proof stress Notch impact energy The requirements applicable to the impact energy which are stated in the recognized standard or the approved material specification shall be satisfied. 2.7 Testing and scope of tests The following tests shall be performed Testing of chemical composition The manufacturer shall determine the chemical composition of each heat and issue the relevant certificate Testing of resistance to intercrystalline corrosion All products shall be tested for resistance to intercrystalline corrosion. For this purpose, at least 2 specimens shall be taken from each heat. The test shall be performed in accordance with DIN or ISO on specimens in the following condition: stabilized steels and steels with a carbon content 0.03 %: sensitized (annealed at 700 C for 30 minutes and quenched in water) all other steels: in the condition in which they are supplied Because of the alloy content, no demands can be made on the steel grades , , , and with regard to their resistance against intercrystalline corrosion; the test shall be omitted for these steels. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 13

14 2.7.3 Tensile testing At least one tensile test specimen shall be taken from each test batch and tested. A test batch comprises for: plates > 20 mm thick: the rolled length plates 20 mm thick: max. 40 rolled plates of approximately the same thickness (deviation max. 20%) originating from the same heat and the same heat treatment batch with a total weight not exceeding 30 t strip and plates taken therefrom: one specimen each from the beginning of the coil all other product shapes: 5000 kg for products of the same shape originating from the same heat and the same heat treatment batch in the case of pressure hull plates, a tensile test specimen shall be taken for each rolled length In the case of plates and wide flats with a width of 300 mm, the specimens shall lie in the transverse direction. For all other product shapes, they may lie in the longitudinal or transverse directions Compression test For pressure hull plates with a fabrication thickness 10 mm a compression test specimen shall be taken for each rolled length. The specimens shall be detached in longitudinal direction at a position with half distance between front face and middle axis. The detaching of specimens may also be in accordance with VG For the compression test DIN shall be used as guidance. Specimens with 10 mm diameter and 30 mm length have to be used. The front face of the specimens have to be lubricated with molybdenum sulfite. Part 2 Chapter 5 Section Notched-bar impact bending test Unless otherwise required by the Society or stipulated in the purchase order, a notched bar impact test with Charpy V-notch specimens is required for: flat products with a thickness > 20 mm rods and bars with diameters or thicknesses > 50 mm If the products are used for operating temperatures below 10 C, the impact test temperature shall be agreed with the Society Testing of surface finish and dimensions The surface finish and dimensions of all products shall be tested and checked by the manufacturer. The products shall also be presented to the surveyor for final testing. In the case of flat products, the underside shall also be inspected as far as possible Testing for use of correct material The manufacturer shall test his products before delivery by appropriate methods as to whether the correct material has been used, and shall confirm this in the acceptance test certificate Testing the permeability For each item or for each plate or strip of non-magnetizable steel, the relative permeability µ r shall be determined on a metallic clean surface for both the delivery condition and the cold-formed state. The relative permeability µ r must not exceed the value of Other tests If there are special requirements regarding resistance to pitting or crevice corrosion, appropriate corrosion tests shall be performed, e.g. according to ASTM G48. The scope of these tests will be determined by the Society from case to case. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 14

15 SECTION 3 STEEL PIPES 1 Pipes of liquid quenched and tempered structural steels 1.1 Scope These rules apply to seamless and welded pipes made of liquid quenched and tempered structural steels that are intended for use in the construction of submarines, for example. For this purpose, suitable pipes made of steel grades VL-M550, VL-M700 or comparable qualities shall be used, insofar as they fulfil the requirements mentioned in these rules. In the case of pipes intended for use in steam boilers, pressure vessels, equipment and pipelines at normal environmental temperatures as well as at elevated temperatures, the requirements set out in RU SHIP Pt.2 Ch.2 Sec.5 [2] shall apply in addition. In the case of pipes intended for cargo-handling and processing equipment with design temperatures below 0 C, the requirements set out in Ch.2 Sec.5 [4] shall apply in addition. 1.2 Heat treatment The pipes shall be supplied in quenched and tempered condition. The minimum tempering temperature is 580 C. A subsequent heat treatment for stress relief is only permissible if expressly approved by the Society. Part 2 Chapter 5 Section Dimensions, length-related dimensions (weights) and limit deviations Dimensions The outer diameters and wall thicknesses of the pipes shall be agreed when the order is placed; for hotfinished pipes preferably according to EN10220 or ISO 4200, and for cold-finished pipes preferably according to EN or EN For the length types of the pipes, Table 1 shall apply: Table 1 Length types and tolerances of the pipes Length type Tolerances [mm] 1) 1) Random length Fixed length ± 500 Exact lengths 6 m 0 to +10 > 6 m, but 12 m 0 to +15 > 12 m By arrangement 1) The pipes are delivered in the lengths occurring during manufacture. These lengths vary according to diameter, wall thickness and manufacturing works, and must be stated by the manufacturer. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 15

16 1.3.2 Tolerances The tolerances for the outer diameter d a of the hot-finished pipes are as follows: d a 50 ± 0.5 mm 50 < d a 160 ± 1% 160 < d a 200 ± 1.6 mm D a > 200 ± 0.8% At points where the surface of the pipes was remedied through mechanical processing, e.g. grinding, it is permissible to exceed the limit value of the diameter to a minor extent, provided the remaining wall thicknesses still complies with requirements. The limit deviations for the wall thickness s of the hot-finished pipes are as follows: 12.5%, whereby the upper limit is given by the permissible weight deviation for a single pipe, see [1.3.5]. By agreement when the order is placed, the tolerance for the diameter of hot-finished pipes with d a > 200 mm can also be referred to the inner diameter. When the order is placed for cold-finished pipes, the tolerances according to EN or EN apply for the outer and inner diameters as well as for the wall thicknesses. By agreement when the order is placed, the hot-finished and cold-finished pipes can also be delivered with closer tolerance for the outer diameter and wall thickness. Part 2 Chapter 5 Section Shape tolerances Roundness tolerance The pipes should be as cylindrical as possible. The roundness tolerance shall lie within the tolerances for the outer diameter Straightness tolerance The hot-finished pipes shall appear straight to the eye. For cold-finished pipes, EN or EN shall apply. Special requirements can be agreed for the straightness tolerance Finish of the pipe ends The pipe ends should be cut off at right angles to the pipe axis. Deburring can be agreed when the order is placed Length-related dimensions (weights) and limit deviations For calculating the weights of the steels to which this section is applicable, a density of 7.85 kg/dm³ is assumed. The values for the length-related dimensions (weights) are given in EN10220 or ISO The following limit deviations are permissible: 8 to +12% for a single pipe 5 to +10% for a consignment of at least 10 t. 1.4 Requirements applicable to the material Chemical composition The chemical composition of the pipe steels must conform to the approved standards or specifications. The chemical composition of the Society grades is given in Sec.2 [Table 1]. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 16

17 1.4.2 Mechanical properties The required values of tensile strength, 0.2% proof stress, elongation and impact energy must be satisfied in tests performed in accordance with the standard or the recognized specification, see Table 2. Table 2 Mechanical properties of the pipes according to the Society grades Grade 0.2% proof stress R p0.2 [N/mm 2 ] Yield strength ratio R p0.2 /R m Tensile strength R m [N/mm 2 ] Elongation A 5 [%] VL-M VL-M Notched-bar impact bending test KV at 20 C [J] min Technological properties When subjected to the ring tests, the pipes must display a capacity for deformation which meets the requirements specified in the following and in RU SHIP Pt.2 Ch.1 Sec.3. The pipes selected for testing shall be subjected to one of the ring tests specified in Table 3, provided that the wall thickness of the pipe does not exceed 40 mm. 95 Part 2 Chapter 5 Section 3 In the ring flattening test (= pipe flattening test), the prescribed distance between the plates H is calculated by applying the following formula: H a D C = distance between the plates [mm] = nominal wall thickness [mm] = outside diameter of pipe [mm] = constant determined by the steel grade In the ring expanding test, the change in the diameter of the specimen expanded to the point of fracture shall at least equal the percentages shown in Table 4, depending on the material. In the drift expanding test applied to austenitic steel pipes a 20% expansion shall be achieved. Where pipes are made of other steels, the requirements of the other relevant standards shall be achieved. Table 3 Types of ring test Outside diameter of pipe [mm] Nominal wall thickness t [mm] t < 2 2 t < t ring flattening test 1), 3) ring flattening test 1), 3) > ring flattening test 1), 3) ring expanding test 1), 3) ring flattening > 146 ring tensile test 2) ring tensile test 2) 1) The drift expanding test may also be applied to welded pipes. 2) Instead of the ring tensile test, the flattening test is applied to pipes with bores of 100 mm. 3) The drift expanding test is applied to seamless and welded pipes in compliance with EN and -2 respectively. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 17

18 Table 4 Diameter change in the ring expanding test Pipe material Minimum expansion [%] for ID/OD ratios of < < < < C- and CMn-steels Mo-, CrMo- and Ni-steels Austenitic steels Testing and scope of tests The following tests shall be performed: Testing of chemical composition The chemical composition of each heat shall be determined by the pipe manufacturer, or, where appropriate in the case of welded pipes, by the manufacturer of the starting material in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.7]. Part 2 Chapter 5 Section Tensile testing Specimens of the sample pipes selected in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.9] shall be subjected to the tensile test. The following additional requirement applies: The tensile tests have to be performed on two pipes each from the first two test batches, and one pipe each from every subsequent batch Notched-bar impact bending test The notched bar impact tests have to be performed on pipes selected in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.9]. Further, the following additional requirement applies: The notch bar impact tests have to be performed on two pipes each from the first two test batches, and one pipe each from every subsequent batch. The bar impact test shall be performed on Charpy V-notch specimens. Where the wall thickness is > 30 mm, the specimens shall be so located that their longitudinal axis lies ¼ of the pipe wall thickness from the outer surface, or as close as possible to this point. The samples shall be so taken and tested that the notch axis lies at right angles to the pipe surface Technological test Unless more extensive testing is prescribed in the standards, one of the ring tests specified in Table 3 shall be performed on one end of 2% of the pipes. To calculate the distance between the platens to be used in the ring flattening test, a value of 0.06 for VL-M550 and 0.05 for VL-M700 shall be assigned to the constant C in the formula given in [1.4.3] High-temperature tensile test Where called for in RU SHIP Pt.2 Ch.2 Sec.5 [1.9], or stipulated in the purchase order, the 0.2% or 1% proof stress shall be determined by the high-temperature tensile test Testing of surface finish and dimensions The tests shall be performed according to RU SHIP Pt.2 Ch.2 Sec.5 [1.11]. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 18

19 1.5.7 Non-destructive testing The welds of all welded pipes shall be subjected by the manufacturer to non-destructive testing, cf. RU SHIP Pt.2 Ch.2 Sec.5 [1.11]. In addition the following applies: The weld seam of the pipes shall be tested over its entire length according to either ISO , acceptance category U2 or ISO , image quality class A Areas in way of pipe ends which have not been tested automatically, shall be subjected either to a manual or semi-automatic ultrasonic test or shall be examined by means of radiographic testing according to the procedures specified above or shall be cut off. The base material is to be tested according ISO , acceptance category U2. The pipe ends have to be tested in accordance with ISO Laminations in circumferential direction of more than 6 mm length are not permitted within the last 25 mm pipe length at each end. Plate or strip edges adjacent to the weld seam are to be tested within a 15 mm wide zone along the weld seam in accordance with ISO or ISO , acceptance category U2 in each case Tightness test All pipes shall be tightness tested by the manufacturer in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.10]. 2 Pipes of non-magnetizable steels Part 2 Chapter 5 Section Scope These rules are applicable to seamless and welded pipes of non-magnetizable steels intended for pipeline construction as well as for tanks and equipment for which non-magnetizability is required. Suitable pipe grades as per SEW 390, and conforming to the material performance sheets WL and WL or other examined and approved specifications, are appropriate for these applications. Pipes which are intended for cargo-handling and processing equipment with design temperatures below 0 C, or for which a special chemical stability in relation to the cargo or operating fluids is required, must additionally comply with the requirements set out in RU SHIP Pt.2 Ch.2 Sec.5 [3] to RU SHIP Pt.2 Ch.2 Sec.5 [4]. 2.2 Heat treatment The pipes shall be supplied in the solution-annealed and quenched condition. The requirement for proper heat treatment is deemed to have been met for hot-pressed pipes if they were quenched in water after removal from the solution-annealing temperature zone. Pipes made of X5NiCrTiMoV26-15 (1.3980) shall be artificially aged at 710 to 750 C after the quenching. 2.3 Requirements applicable to the material Chemical composition The chemical composition of the pipe steels must conform to recognized standards or specifications. Where pipes are to be resistant to intercrystalline corrosion in the delivery state and where the welding is not to be followed by heat treatment (solution annealing), only those pipe grades may be used which are corrosion-resistant in the welded condition, e.g. steels stabilized with Ti or Nb or steels with carbon contents of C 0.03% Mechanical properties The required values of tensile strength, 0.2% proof stress and elongation must be satisfied in tests at room temperature in accordance with the standard or the recognized specification. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 19

20 2.3.3 Technological properties When subjected to the ring tests, the pipes must display a capacity for deformation which meets the requirements specified in [1.4.3] High-temperature characteristics Where pipes are used at elevated temperatures, the required values for the 0.2% or 1% proof stress prescribed in the relevant standards or recognized specifications must be met at the corresponding temperature level, unless otherwise stipulated by the Society Testing the permeability The pipes must be tested for their relative permeability Notch impact energy The required impact energy values must be satisfied in tests at room temperature in accordance with the relevant standard or the recognized specification. 2.4 Testing and scope of tests The following tests shall be performed: Part 2 Chapter 5 Section Testing of chemical composition The chemical composition of each heat shall be determined by the pipe manufacturer Testing of resistance to intercrystalline corrosion Depending on the application and grade of the pipes, a test of resistance to intercrystalline corrosion shall be performed on the following pipes: pipes for use on submarines irrespective of the type of material pipes which do not meet the requirements in respect of stabilization or limited carbon content specified in [2.3.1]. pipes made of stabilized steels or steels with limited carbon contents intended not for application on submarines, where such testing is specially prescribed in view of the anticipated corrosive attack The test conditions shall be as prescribed in Sec.2 [2.7.2] Tensile testing Specimens of the sample pipes selected in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.9] shall be subjected to the tensile test. The following additional requirement applies: The tensile tests have to be performed on two pipes each from the first two test batches, and one pipe each from every subsequent batch Technological test Unless more extensive testing is prescribed in the standards, one of the ring tests specified in Table 3 shall be performed on one end of 2% of the pipes. To calculate the distance between the plates to be used in the ring flattening test, a value of 0.10 shall be assigned to the constant C in the formula given in [1.4.3] High-temperature tensile test Where called for in RU SHIP Pt.2 Ch.2 Sec.5 [1.9] or stipulated in the purchase order, the 0.2% or 1% proof stress shall be determined by a high-temperature tensile test Testing of surface finish and dimensions The tests shall be performed according to RU SHIP Pt.2 Ch.2 Sec.5 [1.11] Tightness test All pipes shall be tightness tested by the manufacturer in accordance with RU SHIP Pt.2 Ch.2 Sec.5 [1.10]. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 20

21 2.4.8 Testing the permeability For each pipe of non-magnetizable steel, the relative permeability µ r shall be determined on a metallic clean surface for both the delivery condition and the cold-formed state. The relative permeability µ r must not exceed the value of Part 2 Chapter 5 Section 3 Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 21

22 SECTION 4 FORGINGS 1 Forgings of liquid quenched and tempered structural steels 1.1 Scope These rules are applicable to forgings made of liquid quenched and tempered structural steels of the grades VL-M550S (1.6780, HY-80), VL-M700S (HY-100) and VL-M900S (HY-130) as well as of equivalent liquid quenched and tempered structural steels with a heat-treated wall thickness up to 400 mm that are used for the construction of naval vessels and floating equipment. These rules are also applicable to rolled steel bars, where they are to be used in place of forgings for the manufacture by machining of shafts, arbours, pins and similar parts. 1.2 Manufacturing process The steels shall be manufactured in works approved by the Society using the AOD, VOD or VODC process, or using another process approved by the Society. In deviation to the stipulations set out in RU SHIP Pt.2 Ch.2 Sec.6 [1.6], forgings made of liquid quenched and tempered structural steels shall exhibit a minimum degree of deformation of 2:1. Part 2 Chapter 5 Section Delivery condition The steels shall be supplied in the quenched and tempered condition. The tempering temperature must lie above 635 C (VL-M550S), above 610 C (VL-M700S) or above 540 C (VL-M900S). 1.4 Surface finish Depending on the purchase order, the forgings shall be delivered as unmachined, rough machined or final machined. Workpieces to be delivered as unmachined should exhibit a smooth surface corresponding to the manufacturing process. Manufacture-related surface imperfections at unmachined points are permitted if their depth lies within the machining allowance. For rough machined surface areas, the permissible depth of the imperfections must be agreed upon. Imperfections within the permissible depth can be removed by grinding. The surfaces of finish-machined forgings shall not exhibit any cracks. 1.5 Dimensions, shape, weight The dimension standards stipulated in the purchase orders or appended drawings shall be applicable for the dimensions and the shape. For the determination of weight, a density of 7.85 g/cm³ shall apply. 1.6 General requirements applicable to the material The chemical composition, the mechanical properties and the hardness shall conform to the data contained in these rules, the relevant standards or the approved specifications. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 22

23 1.7 Testing To provide proof of compliance with the technical requirements, the tests specified below shall be carried out on the completed forging (delivery condition). The results shall be documented Chemical composition The chemical composition is characterized by means of the ladle analysis. The manufacturer shall determine the proportions of all the elements specified in Table 1 by applying the usual methods Mechanical properties The requirements for the mechanical properties are given in Table Tensile testing The mechanical properties shall be verified by tensile testing. For preparing the test specimens, forgings with similar dimensions and nominal weights up to 500 kg which originate from the same heat and form part of the same heat treatment batch may be grouped into test batches in accordance with Table 3. Table 1 Chemical composition of liquid quenched and tempered forging steels Brief name VL grade C Si Mn P S Cr Mo Ni As Cu Sb Sn Ti V Part 2 Chapter 5 Section 4 15NiCrMo NiCrMo 12-6 VL-M550S VL-M700S VL-M900S Min ) Max Min ) Max Min ) Max ) For vacuum-carbon deoxidization, Si min = 0.05 % shall apply. Table 2 Mechanical properties Grade R p0.2 Yield strength ratio Reduction in area Elongation A 5 Notched-bar impact bending test (transv. or tangential) [N/mm 2 ] R p0.2 /R m [%] [%] KV [J] 1) VL-M550S (l) 50 (q) 20 (l) 18 (q) 85 (at -20 C) 70 (at -85 C) 2) VL-M700S (l) 45 (q) 18 (l) 16 (q) 85 (at -20 C) 70 (at -85 C) 3) VL-M900S (at -20 C) 1) Average value of 3 samples; the smallest single value must be at least 90% of the minimum average value. 2) 40 J for wall thickness > 150 mm 3) 40 J for wall thickness > 100 mm (l) in longitudinal direction (q) in transverse direction Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 23

24 Table 3 Heat treatment weight of individual forging and number of forgings per test batch Heat treatment weight of individual forging [kg] Number of forgings per test batch up to > 15 to > 150 to > 300 to Two samples shall be taken from each test batch. One specimen is sufficient for: quantities of forgings 10 quantities of forgings 30 if the weight of the forgings does not exceed 15 kg. For batchwise testing, the hardest and softest forgings in each batch shall be selected for testing, see [ ]. In the case of forgings with unit weights of more than 500 kg, a test specimen shall be taken from every forging. When the length of such forgings, excluding test metal, exceeds 2 m, a test specimen shall be taken from each end of the forging. Part 2 Chapter 5 Section Notched-bar impact bending test The forgings shall be subjected to the notched bar impact test using Charpy V-notch specimens. The number of sets of test specimens (3 specimens per set) shall be determined in the same way as the number of tensile test specimens. Unless agreed otherwise, the notched bar impact test shall be carried out at -20 C. The notch shall be made perpendicularly to the surface of the forging Hardness test Each forging in the quenched and tempered condition shall be subjected to a hardness test Dimensions, shape and weight examination The dimensions and shapes shall be examined according to the relevant drawings and/or standards. The weight shall be determined by weighing Test of surface finish An examination must be carried out to ascertain whether the surface finish stipulated in the purchase order has been attained and whether the requirements set out in RU SHIP Pt.2 Ch.2 Sec.6 [1.12] to RU SHIP Pt.2 Ch.2 Sec.6 [1.13] have been observed. The surface crack test shall be carried out by non-destructive testing methods according to RU SHIP Pt.2 Ch.2 Sec.6 [1.12]. The determination of the crack depth is performed as chosen by the manufacturer Testing of the internal condition The test shall be carried out in compliance with the requirements set out in RU SHIP Pt.2 Ch.2 Sec.6 [1.12] Identification The forgings shall be tested to ascertain whether the correct material has been used Marking test The markings shall be examined for correctness. Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 24

25 2 Forgings of non-magnetizable steels 2.1 Scope These rules are applicable to bars, open-die forgings and drop forgings as well as to seamless rolled rings of non-magnetizable steels intended for the construction of naval vessels and floating equipment. They are also applicable to rolled steel bars, where it is to be used in place of forgings for the manufacture by machining of shafts, arbors, pins and similar parts. 2.2 Permissible materials and delivery conditions The following materials may be used: materials listed in the Material Handbook of Military Technology 1 in accordance with the material performance sheets (WL) listed in Table 4. other materials approved by the Society according to other standards or specifications Table 4 Materials of forgings of non-magnetizable steels WL Part Material Part 2 Chapter 5 Section , 3 X2CrNiMnMoNNb , 3 X2CrNiMoN , 4 X2CrNiMoN , 3, 6 X2CrNiMnMoNNb , 3, 6 X2CrNiMnMoNNb The required delivery condition shall be stipulated by the customer in the purchase order. In the case of forgings intended for the manufacture of flanges, nozzles, valve housings, socket welding and welding neck components for boilers, pressure vessels, equipment and pipelines or for design temperatures below 0 C, the requirements set out in RU SHIP Pt.2 Ch.2 Sec.6 [6] to RU SHIP Ch.2 Sec.6 [8] shall be observed in addition. 2.3 Surface finish The surface of the forgings shall comply with the agreements made on placing the order and the requirements set out in RU SHIP Pt.2 Ch.2 Sec.6 [1.12] to RU SHIP Pt.2 Ch.2 Sec.6 [1.13]. 2.4 External and internal defects All products shall be delivered without defects, which could impair the usability. Surface defects on unmachined products shall be removed by mechanical processing within the tolerances. During the removal of local defects the transitions must be smooth. The radius of the transition shall be at least three times the depth. Cracks at rough-machined and final-machined forgings are not permissible. For the non-destructive tests, the prerequisites relating to the relevant testing method and those applying to the external condition of the products must be fulfilled. In addition a subdivision into testing zones shall be undertaken and statements on the acceptance level (quality class according to EN 10228) shall be made 1 Material Handbook of Military Technology, DIN - Deutsches Institut für Normung e.v., Berlin Rules for classification: Naval vessels DNVGL-RU-NAVAL-Pt2Ch5. Edition December 2015 Page 25