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DNV GL AS

RULES FOR CLASSIFICATION

Underwater technologyEdition December 2015

Part 2 Materials and welding

Chapter 5 Materials and welding for UWTsystems

FOREWORD

DNV GL rules for classification contain procedural and technical requirements related to obtainingand retaining a class certificate. The rules represent all requirements adopted by the Society asbasis for classification.

© DNV GL AS December 2015

Any comments may be sent by e-mail to [email protected]

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 shallpay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to tentimes 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 DNV GL AS, 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.

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Rules for classification: Underwater technology — DNVGL-RU-UWT-Pt2Ch5. Edition December 2015 Materials and welding for UWT systems

DNV GL AS

CURRENT – CHANGES

This is a new document.

The rules enter into force 1 July 2016.

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CONTENTS

Current – changes...................................................................................................... 3

Section 1 General....................................................................................................... 61 Introduction............................................................................................62 Procedural requirements........................................................................ 63 Marking...................................................................................................8

Section 2 steel materials for UWT Systems................................................................91 Introduction............................................................................................92 Documentation and certification requirements....................................... 93 Material requirements............................................................................ 9

Section 3 Non-Iron metallic materials for UWT systems.......................................... 121 Introduction..........................................................................................122 Welding.................................................................................................12

Section 4 Corrosion protection................................................................................. 131 Introduction..........................................................................................132 Documentation and certification requirements..................................... 133 External Protection............................................................................... 134 Internal protection............................................................................... 14

Section 5 Fibre Reinforced Plastics (FRP)................................................................ 151 Introduction..........................................................................................152 Approval............................................................................................... 153 Documentation and certification requirements..................................... 154 Repair of components...........................................................................16

Section 6 Acrylic materials.......................................................................................171 Introduction..........................................................................................172 Approval............................................................................................... 173 Documentation and certification requirements..................................... 17

Section 7 Syntactic foams........................................................................................ 191 Introduction..........................................................................................192 Documentation and certification requirements..................................... 193 Requirements and testing.....................................................................20

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Section 8 Welding, post-weld heat treatment and non-destructive testing...............211 General................................................................................................. 212 Procedure tests.................................................................................... 213 Butt welds............................................................................................ 214 Fillet welds........................................................................................... 215 Welding technique................................................................................ 226 Post weld heat treatment.....................................................................247 Non-destructive testing........................................................................ 25

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SECTION 1 GENERAL

1 Introduction

1.1 GeneralMaterials shall be suitable for the intended purpose and for the manufacturing processes applied, e.g.welding. Principally, the requirements of SHIP Pt.2 Ch.1 to SHIP Pt.2 Ch.4 are valid. This chapter representsa supplement to the Society's Rules for materials and welding specifying the special requirements formaterials used in UWT Systems.Materials for UWT Systems and their equipment shall be selected in the way that the system can be safelyoperated under defined conditions of the environment and of the missions during the intended life time.Materials shall be resistant against influences of the surrounding media as far it is required for the function ofthe UWT System or vehicle and if another sufficient protection is not possible. In addition, chosen materialsshall be compatible to each other.Non-metallic materials retaining pressurised gas shall be considered for gas-permeability.

1.2 ScopeThese rules apply to materials used for all kind of UWT Systems.

1.3 ApplicationThe requirements in this chapter apply to steel materials for pressure hulls and pressure vessels for humanoccupancy, steel materials and non-iron materials for structures, and appropriate means of corrosionprotection, as well as to fibre reinforced plastics (FRP), acrylic materials and syntactic foams.Materials other than those mentioned in this chapter may be used provided they have been proven to besuitable for the intended application. If no recognized standards are available, the relevant specificationsshall be submitted to the Society for assessment and approval.

1.4 ReferencesTable 1 References

Reference Title

EN 10204 Metallic products - Types of inspection documents

ASME PVHO-1 Safety Standard for Pressure Vessels for Human Occupancy

1.5 Terminology and definitionsFor definitions see Pt.1 Ch.1 Sec.1 [1.2].

2 Procedural requirements

2.1 Certification RequirementsMaterials for UWT Systems shall meet the requirements given in the relevant chapters and sections in SHIPPt.2 Ch.2 and SHIP Pt.2 Ch.3.

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The materials used shall have certificates according to Table 1. For definition of the different types ofcertificates, see Pt.1 Ch.1 Sec.4

Table 2 Certificates for materials

Object Certificatetype Issued by Certification standard Additional description

plates for the pressure hull VL Society DNV GL rules

load bearing element, 1st ordercomponents3 VL Society DNV GL rules

load bearing element, 2nd ordercomponents3 W manufacturer DNV GL rules

pipes and sockets > DN 50 VL Society DNV GL rules

pipes and sockets ≤ DN 50 W manufacturer DNV GL rules

forgings, forged flanges > DN250 VL Society DNV GL rules

forgings, forged flanges ≤ DN250 W manufacturer DNV GL rules

steel castings VL Society DNV GL rules

bolts ≥ M30 VL Society DNV GL rules

bolts ≥ M16 alloyed andtempered steel VL Society DNV GL rules

other bolts1 W manufacturer DNV GL rules

nuts≥ M30 VL Society DNV GL rules

other nuts1 W manufacturer DNV GL rules

acrylic plastic VL Society 2 ASME PVHO-1and DNV GL rules

test reports (TR) arenot applicable for

pressure hull materials

1) for load bearing elements and pressure vessels only2) Proof by independent institution may be recognised, see also Pt.4 Ch.7 Sec.3 [1.3.1]3) for further information see Pt.3 Ch.6

2.2 Proof of material quality characteristics

2.2.1 Proof of the material quality characteristics used for UWT Systems shall be supplied in form ofmaterial certificates according to Pt.1 Ch.1 Sec.4. The type of Certificates required for the product concernedis indicated in the tables of the following sections. Unless otherwise specified, the testing authority foracceptance tests for material certificates is the Society.Materials for main pressure retaining parts like pressure hulls, pressure vessels etc. shall be certified by theSociety.

2.2.2 The evidence to be supplied in respect of the product characteristics not included in the tables of thefollowing sections shall be agreed with the Society.

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2.2.3 For small parts, e.g. supports for consoles, welding lugs or other, not load-bearing and not pressureloaded elements, Test Reports shall be provided.

2.2.4 Manufacturing certificates according to EN 10204 may be accepted. Acceptance shall be agreed withthe Society.

2.3 Approval of manufacturersThe manufacturer of materials and products for UWT Systems shall hold a valid approval in compliance withCh.1. If several manufacturers are working on the same product, the scope of their shop approvals shallmeet the manufacturing steps performed, as appropriate. The requirements on workshop approvals shall beagreed with the Society.

3 MarkingMaterial for UWT Systems shall be marked according to the applied standards.

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SECTION 2 STEEL MATERIALS FOR UWT SYSTEMS

1 Introduction

1.1 General

1.1.1 Other material grades may be acceptable after provided acceptance by the Society. In such cases,additional testing will be required and qualification procedures shall be reconsidered.

1.1.2 Additional to the requirements in Pt.2 Ch.2 the following steel materials for UWT Systems shall meetthe requirements defined in [3.2].

1.1.3 Additional to the requirements in Pt.2 Ch.2 the following steel materials for structures shall meet therequirements defined in [3.3].

1.1.4 For corrosion protection, see Sec.4.

2 Documentation and certification requirements

2.1 Documentation requirements2.1.1 GeneralFor documentation requirements, see Pt.2 Ch.2 Sec.1.

2.2 Certification requirements2.2.1 GeneralFor certification requirements, see Sec.1.

3 Material requirements

3.1 General

3.1.1 Rolled or forged steels and steel castings with guaranteed ductility and toughness according to Table 2are normally to be used for pressure hulls and pressure vessels for human occupancy and fabrication.Steel plates, profiles and bars shall be made of fine-grained special steels with sufficient share of fine graincreating elements, e.g. Al, Nb, V or Ti according to the SHIP Pt.2 Ch.2 shall be produced under considerationof the requirements in [3.2] and [3.3].

3.1.2 Steel materials other than those mentioned in [3.1.1] may be used provided they have been proven tobe suitable for the intended application. If no recognized standards are available, the relevant specificationsshall be submitted to the Society for assessment and approval.

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3.2 Special requirements applicable to materials for pressure hulls andpressure vessels for human occupancy3.2.1 DuctilityAll metals shall possess sufficient ductility (in terms of the elongation measured by tensile test). Theelongation at fracture (A) shall conform with the values stated in the standard or material specification andshall not be less than 16% for steel. For screws an elongation of fracture A ≥ 14% is required.

3.2.2 Impact energySteel grades shall conform to the impact energy values measured by notched bar impact test stated in thestandard or material specification. In addition the following shall be complied with:

— Plates shall possess an impact energy of at least 30 J measured on ISO V-notch transverse specimens at atest temperature corresponding to the plate thickness in accordance with Table 2.

— Pipes shall possess an impact energy of at least 27 J measured on ISO V-notch transverse specimensresp. 41 J on longitudinal specimens at 0°C.

— Cast iron shall possess an impact energy of at least 31 J measured on ISO V-notch specimens at 20°C.— Forgings and steel profiles and bars which are load bearing and are welded directly to the pressure hull,

e.g. reinforcing rings, stiffeners, shall possess an impact energy of at least 27 J measured in ISO V-notchlongitudinal specimens at a test temperature of 0°C.

— Screws shall possess an impact energy of at least 52 J for tempered steels resp. at least 40 J foruntempered steels measured on ISO V-notch specimens at a test temperature of 20°C.

Table 1 Test temperatures for notched bar impact tests

Plate thickness [mm] Test temperature [°C]

≤20

> 20 ≤40

> 40 ≤60

> 60

0

- 20

- 40

by agreement

Table 2 Approved materials for pressure hulls

Product type Grade of material Society rules, standard or specification

platesnormalized and heat treated fine grained steelsand pressure vessel steels with characteristicsaccording to [3.2]

EN 10028-3, -6

endsnormalized and heat treated fine grained steelsand pressure vessel steels with characteristicsaccording to [3.2]

profiles and bars

general-purpose shipbuilding and structuralsteels, provided these are killed, also fine-grained structural steels with characteristicsaccording to [3.2]

EN 10025-2, -3, -4, -6,EN 10028-3, -5, -6

pipes seamless and welded ferritic steel pipes withcharacteristics according to [3.2]

for wall thickness ≤ 20 mm: 20 mm <wall thickness ≤ 40 mm:

forgings forgings, pressure vessels and piping withcharacteristics according to [3.2]

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Product type Grade of material Society rules, standard or specification

steel castings steel castings, pressure vessels and piping withcharacteristics according to [3.2] EN 10213

bolts and nuts unalloyed or alloy steel bars with characteristicsdefined in [3.2] ISO 3506-1 and -2

viewports acryl glass panes Sec. 6

3.2.3 Stainless steel cladding, stainless steel tubes, fittings etc. which are welded to pressure vessels ofnon-stainless steel shall be of a stabilised or low-carbon grade. Acceptable grades are given in the applicablestandards or in SHIP Pt.2 Ch.2 Sec.4.

3.2.4 Special attention should be paid to the design and choice of material for the construction of pressurevessels containing oxygen.(IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.4.1)

3.2.5 [3.2.4] applies also for piping.

3.3 Special requirements applicable to materials for structures

3.3.1 The requirements for the certification of materials for structural elements can be taken from Sec. 1,Table 2.

3.3.2 Materials for the structure shall be compatible with the material it is mounted/welded to, but thestrength parameters may be different. This shall be especially considered where the exostructure is welded tothe pressure hull.

3.3.3 If the electrochemical characteristics of the material are different, corrosion protection may becomenecessary.

3.4 Non-destructive testingNon-destructive tests of the material shall apply in the range described in the following.

3.4.1 Plates with a thickness above 8 mm shall with regard to their internal defects as a minimum satisfy therequirements for Class 2, Table 1 of Stahl-Eisen-Lieferbedingungen (SEL) 072 or S2/E3 of the standard EN10160 or comparable standards.Zones for longitudinal, round and socket seams with a width equivalent to the plate thickness, but at least 50mm, shall satisfy the requirements according to Class 1, Table 2 according to SEL 072 respectively of qualityclass E3 according to EN 10160.Areas for the connection of lifting eyes, elements of the structure and other plates, which may also bestressed in thickness direction, shall satisfy the requirements according to Class 0, Table 1 according to SEL072 respectively of quality class S3 according to EN 10160.

3.4.2 For forgings greater DN 250 the material quality shall be checked by the manufacturer using suitabletest procedures according to the SHIP Pt.2 Ch.2 Sec.6. The tolerance boundaries shall be agreed with theSociety depending on the type of the component.

3.4.3 The manufacturer shall submit the proof for the non-destructive tests to the Society.

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SECTION 3 NON-IRON METALLIC MATERIALS FOR UWT SYSTEMS

1 Introduction

1.1 GeneralMetallic materials other than those mentioned in Sec.2 may be used for UWT Systems provided that theyhave been proven to be suitable for the intended application. If no recognized standards are available, therelevant specifications shall be submitted to the Society for assessment and approval.The requirements of SHIP Pt.2 Ch.3are to be observed

2 Welding

2.1 GeneralAdditional to the general requirements for welding of SHIP Pt.2 Ch.4, the welding of pressure hulls andpressure vessels for human occupancy shall also meet the requirements for welding n Sec.2 as far asapplicable.

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SECTION 4 CORROSION PROTECTION

1 Introduction

1.1 Scope

1.1.1 UWT Systems, structures and belonging components made of metallic materials shall be effectivelyprotected against corrosion.Corrosion protection shall be considered already in the design phase.The requirements of RU SHIP Pt.3 Ch.3 Sec.4 shall be observed.

1.1.2 Locations which for constructional reasons are not accessible shall be provided with a durable corrosionprotection.

1.1.3 In the case of other materials as steels, such as aluminium, special conditions shall be agreed with theSociety.

1.1.4 The surface of the window seats cavity shall be protected against corrosion.

1.1.5 Paints, cabling and other materials in PVHOs shall be considered for toxic or noxious properties.

1.1.6 Precautions shall be taken to avoid galvanic corrosion.


2.1 Documentation requirements2.1.1 GeneralFor general requirements regarding documentation, including definition of the info codes, see Pt.1 Ch.3Sec.1.For full definition of the documentation types, see Pt.1 Ch3. Sec.2.

2.1.2 CorrosionDocumentation shall be submitted as required by Table 1.

Table 1 Documentation requirements

Object Documentation type Additional description Info

all surfaces endangered bycorrosion M040 coating specification - FI

main outside surfacesendangered by corrosion

M050 cathodic protectionspecification, calculation anddrawings

- FI

internal painting of pressurehull (PVHO)

M041 coating specificationrelating to hazardousmaterials

including toxicity statement for internalpainting according to ASME PVHO-1 Standard FI

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3 External Protection

3.1 Sacrificial anodesAn active corrosion protection shall be secured e.g. by mounting of sacrificial anodes in sufficient number andcomposition.

3.2 CoatingThe coating system, without antifouling, shall have a minimum dry film thickness of 250 mym on thecomplete surface. It shall be compatible to cathodic protection in accordance with recognized standards andshall be suitable for being cleaned underwater by mechanical means.

4 Internal protection

4.1 Dry chambers and compartmentsFor equipment, fittings, insulation, paintwork and preservative coatings inside UWT Systems, use may onlybe made of those materials and media which do not release any toxic or severe irritant gases under theatmospheric conditions mentioned in Pt.3 Ch.4 Sec.3 [3]. Wherever possible, this also applies to the effectsof heat.

4.2 Wet chambers and compartments

4.2.1 Anti-corrosion coatings exposed to the chamber conditions shall meet the requirements stated in thissection. In addition, they shall not tend to blister or flake off under hyperbaric conditions. In wet chambers itmay be necessary to make special provision for the effect of helium-saturated seawater.Wet chambers shall be provided with an adequate anodic protection system, if reasonable.

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SECTION 5 FIBRE REINFORCED PLASTICS (FRP)

1 IntroductionThis section describes requirements of fibre reinforced plastics (FRP) which are used for UWT Systems inaddition to the general requirements set up in SHIP Pt.2 Ch.2 Sec.3. Consider also the requirements forpractical application in Pt.3 Ch.6 Sec.5.Normally, FRP materials are excluded from the usage as hulls subject to external pressure and pressurevessels for human occupancy. Exceptions can be made in agreement with the Society.

2 Approval

2.1 Suitability

2.1.1 The materials of FRP components shall be assed and approved by the Society considering the UWTSystem.

2.1.2 The manufacturer or user shall document the materials suitability for its intended purpose. Thedocumentation shall take into account possible connection with other materials.

2.2 Types of materialsThe following materials can be applied for construction of FRP components for UWT Systems:

— laminated resins, e.g. cold-setting or hot-setting unsaturated polyester (UP) resins or cold setting epoxy(EP) resins

— reinforcing materials, e.g. fibre reinforcements made of glass or carbon— prepregs as reinforcing materials, which are preimpregnated with a thermosetting resin and which can be

processed without any further addition of resin or hardener— core materials, e.g. rigid foams with adequate compressive strength— adhesives, e.g. cold- or hot-setting thermosetting adhesives or hot-melt adhesives— flame retardant laminates produced by additives to the resin system, whereby the viscosity of the resin or

the mechanical properties of the manufactured laminates are not been changed essentially— other materials may be approved in agreement with the Society.

2.3 ManufacturingFor components made of FRP, the manufacturer’s quality system shall secure that the special requirementsfor UWT Systems, e.g. avoidance of bubbles, pressure resistance, etc. are met.


3.1 Documentation requirements3.1.1 GeneralFor general requirements regarding documentation, including definition of the info codes, see Pt.1 Ch.3Sec.1.For full definition of the documentation types, see Pt.1 Ch.3 Sec.2.

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3.2 Certification requirements3.2.1 GeneralFor a definition of the certificate types, see Pt.1 Ch.1 Sec.5.

Table 1 Certification requirements

ObjectCerti-ficatetype

Issued by Certificationstandard* Additional description

FRP for pressurehull VL Society DNV GL rules to be approved for underwater application

FRP for loadbearing elements VL Society DNV GL rules to be approved for underwater application

FRP forexostructure MC Society DNV GL rules to be approved for underwater application

materials of FRPcomponents VL Society DNV GL rules to be approved for underwater application

materials inconnection withother materials

W manufactureror user DNV GL rules including suitability for the intended purpose

4 Repair of components

4.1 Repair of components of UWT Systems shall be performed in compliance with the requirements given in SHIPPt.2 Ch.3 Sec.3 and Pt.3 Ch.6 Sec.5.

4.2 Repairs of structural FRP-components shall only be performed by workshops which are approved by theSociety.

4.3 For the approval of a repair, all design and repair drawings, which are needed to assess the repair, shall besubmitted to the Society. The repair plan shall be examined and approved by the Society.

4.4 A report shall be established for each repair which shall be signed by the head of the repair team.

4.5 If the materials and laminates used for the repair are not identical to those applied when the component wasmanufactured, equivalence of the combination of materials shall be verified with respect to their propertiesand suitability.

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SECTION 6 ACRYLIC MATERIALS

1 IntroductionThis section describes requirements of acrylic materials which are used for UWT System applications inaddition to the general requirements set up in SHIP Pt.2 Ch.3 Sec.5.Acrylic materials are permitted for flat or curved windows of view ports including pressure hulls or partsof hulls applied for UWT Systems. They shall be made of polymethyl methacrylate (PMMA) and shall bemanufactured as unlaminated, casted material.

2 Approval

2.1 General

2.1.1 Materials for acrylic windows shall be manufactured, heat treated and tested in accordance with arecognised standard for underwater and pressure applications (e.g. ASME PVHO-1, Section 2).The manufacturer shall inform the Society about the applied standard before manufacturing. Application ofthe standard shall be agreed with the Society. Any deviations from the applied standard shall be agreed onwith the Society.Approval shall be granted on the basis of a thorough test of material from the current production and areport after inspecting the works, and verification of QA and QC against requirements given in ASME PVHO-1.

2.2 ManufacturingAn assessment during the complete manufacturing process shall cover composition of the polymericcomponents, manufacturing conditions of the semi-finished product, and conditions on curing, machining andfinishing including heat treatment. Further, scientifically founded requirements on minimum mechanical andoptical properties as well as appropriate test standards shall be the base for material verification by testingsuitable test samples during the manufacturing process. All steps of the window design and manufacturingprocess shall be accompanied and documented by suitable forms, which shall be provided by the standard,too.


3.1 Documentation requirements3.1.1 GeneralFor general requirements regarding documentation, including definition of the info codes, see Pt.1 Ch.3Sec.1.For full definition of the documentation types, see Pt.1 Ch.3 Sec.2.

Object Documentation type Additional description Info

manufacturer workshop approval FI

manufacturer's declaration of conformity FIacrylic material

material properties FI

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ObjectCertificate

typeIssued by Certification

standard Additional description

material manufacturer VL Society ASME PVHO-1

to be basis on a thorough testof material from the currentproduction and a report afterinspecting the works, andverification of QA and QCagainst requirements given inASME PVHO-1

acrylic material W manufacturer ASME PVHO-1

additionally to the certificationrequirements of SHIP Pt.2 Ch.3Sec.5:

— material test results andproperties

3.3 Certification of cast materialEach delivery of cast material shall be accompanied by a certificate issued by the manufacturer in compliancewith SHIP Pt.2 Ch.3 Sec.5.Material properties and test results required according to ASME PVHO-1 are to be stated in the certificate.

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SECTION 7 SYNTACTIC FOAMS

1 IntroductionSyntactic foams are manufactured using a thermosetting plastic matrix, in which glass microspheres aredispersed. The small wall thickness of the glass microspheres (microscopic glass particles completelyenclosing a void) in conjunction with the formation of the matrix results in a hydrostatically resistant, lowdensity material.Materials for rigid buoyant bodies shall be suitable for the proposed pressure and temperature ranges andshall have a low water absorption factor. Compare also the requirements for syntactic foams increasingbuoyancy in Pt.3 Ch.6 Sec.6.


2.1 Documentation requirements2.1.1 GeneralFor general requirements regarding documentation, including definition of the info codes, see Pt.1 Ch.3 Sec.1For full definition of the documentation types, see Pt.1 Ch.3 Sec.2.



Object Certi-ficate type Issued by

Certifi-cationstan-dard*

Additional description

syntacticfoam VL /TA Society

— density (e.g. according to EN ISO 845)— tensile strength— uniaxial compressive strength (e.g. according to ASTM

D695-02a)— buoyancy variation in regard to nominal diving pressure— seawater intake (e.g. according to ASTM D2735)— hydrostatic crush pressure

The tests shall be made with different specimen of differentfabrication batches to be applied for the actual submarine project.

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3 Requirements and testing

3.1 ApprovalThe materials used shall be assessed and approved by the Society. A certificate according to Table 1 shall beissuedAppropriate test reports shall be provided and the suitability for the intended range of external pressure andtemperature shall be proven.

3.2 Longterm checkIf reasonable a cube of 1 dm³ volume shall be installed with the other foam elements of the same batchat the UWT System and its condition shall be tested at least at the occasion of a class renewal survey. Thescope of tests shall comprise at least a visual inspection and the further scope of testing shall be agreed withthe Society.

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SECTION 8 WELDING, POST-WELD HEAT TREATMENT AND NON-DESTRUCTIVE TESTING

1 GeneralThe welding of pressure vessels, pressure hulls, pressure vessels for human occupancy and structures forUWT systems shall meet the following requirements.

2 Procedure testsBefore welding work is commenced, the properties of the joints to be welded shall be proven to the Societyby welding procedure tests at the manufacturer's works in accordance with SHIP Pt.2 Ch.4.

3 Butt weldsAll butt welds shall be performed as full-penetration, multi-pass welds executed from both sides.

4 Fillet weldsThe proof of fillet welds shall be performed according to RU SHIP Pt.3 Ch.13 Sec.1. If no detailed proof bycomputation is required, the dimensioning shall follow Table 1. Depending on accessibility a suitable testprocedure shall be applied and to be agreed with the Society.

Table 1 Thickness of seams for double sided full-penetration fillet welds and double-bevel welds

Construction elements depending on the load Seam thickness a/tmin

pressure hull (PH):

— web of frame with shell of PH— web of frame with flange— web frame with PH— bulkhead (exception pressure tight bulkhead) with shell of PH— bulkhead (exception pressure tight bulkhead) with flange of web of PH— deck with shell of PH— pressure tight bulkhead with shell of PH

0.35

0.35

0.50

0.50

0.35

0.401)

pressure tight bulkhead:

— stiffeners on bulkhead— flange of web with web— penetrations in bulkhead— supporting deck with bulkhead

0.50

0.50

0.50

0.50

compensating tanks:

— connection to the main structure 0.50

walls/decks/bulkheads of tanks:

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Construction elements depending on the load Seam thickness a/tmin

— plating together— plating with shell of PH— stiffeners with plating— girders with plating

0.40

0.40

0.25

0.30

exostructure:

— plating together— frames with shell— web frames— bulkheads— frame connections to shell of PH— plating to the shell of PH— keel plates with web— brackets

0.35

0.25

0.30

0.30

0.40

0.35

0.50

0.45

foundations:

— longitudinal and transverse girders— stiffeners and brackets

0.50

0.40

decks and walls:

— plating together— plating with shell of PH— stiffeners with plating

0.30

0.30

0.15

1)

— tmin = smaller thickness of the plates to be connected— Tension and bending loaded cruciform joints shall be connected with a/t = 0.7

5 Welding technique

5.1 Welds must exhibit full penetration over their entire cross section and must not have any cracks or lack offusion defects. Wherever possible, the root shall be grooved and capped.

5.2 Before welding is commenced, it shall be ascertained that the plate edges are in alignment within the limitsspecified in Pt.3 Ch.3 Sec.5 [2.5.3].

5.3 If the plates are of unequal thickness the requirements in SHIP Pt.4 Ch.7 Sec.7 [2.2.7] shall be observed.

5.4

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In the case of the pressure hull consists of several rings, the longitudinal seams shall be staggered. As aguide, the amount of stagger should be 4 times the plate thickness, but at least 100 mm.

5.5 Corner welds and similar welded joints which are subjected to considerable flexural stresses under adverseconditions of fabrication or service are only acceptable if the Society raises no objection to the method ofexecution.

5.6 Holes and cut-outs in or immediately adjacent to welds, especially longitudinal welds, shall be avoided.

5.7 Butt-welded joints in walls under pressure shall not be intersected by fillet welds of fitments. If intersectionof fitments with pressure hull welds cannot be avoided, sufficiently large cut-outs shall be made in thefitments in the area of the butt welds in the pressure hull.

5.8 Weld preparation for welds between the pressure hull wall and domes and between the domes and thecorresponding nozzles shall be carried out in accordance with recognized standards.

5.9 All welds on nozzles, domes and other components which penetrate the pressure hull and all welds betweenflanges and hull or nozzle must be welded with full penetration over the entire wall thickness of the hull orthe nozzle.

5.10 Fillet welds of stiffeners and fitments which may induce stresses in the walls of the pressure hull shall be laiddown in more than one pass.

5.11 Welding of components from ferritic steels in cold-formed areas where the outer fibres have been stretchedby more than 5% (Dm < 20 ∙ s for cylindrical shell rings) is only allowed if the effects of cold forming havebeen cured by means of appropriate heat treatment. This shall generally be accomplished by normalizingheat treatment or quenching and tempering. This requirement may be waived if proof is furnished that theproperties of the material are no more than insignificantly impaired with regard to the intended use.

5.12 Every weld in a pressure hull component shall be marked in such a way that its location remains recognizableand the welder concerned can be identified at any time. Both of these may be evidenced either by stampingthe weld accordingly or by making entries in drawings, welding schedules or other records.

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6 Post weld heat treatment

6.1 Where post weld heat treatment is required by the relevant standard or the Society’s approval document therequirements in SHIP Pt.4 Ch.7 Sec.3 shall be observed.

6.2 Welded components must be heat-treated after welding in accordance with the stipulations of the relevantstandards or the Society's approval document.

6.3 The post-weld heat treatment shall normally consist of stress relief heat treatment.

6.4 Components fabricated from steels which have undergone normalizing heat treatment shall be subjected tonormalizing heat treatment if:

— the required properties of the welded joint can only be established by normalizing heat treatment

or

— the component has undergone hot-forming after welding, unless hot-forming was completed within atemperature range equivalent to normalizing heat treatment.

6.5 Components fabricated from quenched and tempered steels shall be subjected to quenching and temperingif:

— the required properties of the welded joint can only be established by quenching and tempering

or

— the component has undergone hot-forming after welding.

If, in the case of air-hardened and tempered steels, the hot-forming of the component was on the wholeperformed under the conditions applicable to normalizing heat treatment, tempering alone is sufficient.

6.6 Post-weld heat treatment may be dispensed with if the following conditions are met:

— Prior to welding, the materials must be in the heat-treated condition specified in the relevant standards orin the Society's approval document. This condition is also deemed to be met if the required heat-treatedcondition is only attained during subsequent fabrication.

— The nominal wall thickness at the joints may not exceed 30 mm.— In the chemical composition (melt analysis) of the base material and the weld metal, the following

contents may not be exceeded:C 0.22%, Si 0.50%, Mn 1.40%,Cr 0.30%, Cu 0.30%, Mo 0.50%,Ni 0.30%, V 0.20%;

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In this context, the following conditions shall also be satisfied:Cr + Ni ≤ 0.30% and Mn + Mo + V ≤ 1.6%.

These conditions may be relaxed in the case of steels which have been rendered resistant to brittle fractureand hardening by special metallurgical measures. Their suitability and properties shall be demonstratedto the Society after an adequate period of proving. The steels' resistance to brittle fracture, resistance tohardening and weldability must be equivalent to those of steels falling within the above analytical limits. Forthe weld metal, at a C content ≤ 0.10% the Si content shall be ≤ 0.75%, the Mn content ≤ 2.0% and thesum of the Mn, Mo and V contents ≤ 2.5% if welding consumables are used which produce a weld metal witha particularly high toughness, e.g. by using welding consumables with basic characteristics.

6.7 Joints between carbon-manganese and austenitic steels (weld metal) must not, as a general rule, besubjected to heat treatment due to the risk of carbon diffusion, except where the welds are made usingnickel-base filler materials.

6.8 Documentary proof of the heat treatments described in para. [6.2] to [6.5] shall be provided by means ofa works certificate to EN 10204 or ISO 10474, as applicable (DIN 50049) which shall state the method,temperature and duration of the heat treatment and the method of cooling. Any special heat treatment, e.g.temporary cooling after welding prior to tempering treatment, shall be recorded in the works certificate.

7 Non-destructive testing

7.1 On completion of the manufacturing work and of any necessary heat treatment the pressure hull andstructures shall be subjected to a constructional check at the manufactures work in presence of a Societysurveyor, checking that the dimensions, thicknesses, materials, welding, etc. are in accordance with theapproved drawings.

7.2 For pressure hull and loadbearing elements non-destructive testing shall be carried out as follows:

— All welded joints shall be subjected to visual inspection and shall also be examined for surface cracks bysuitable means like dye penetration inspection.

— All butt welded joints shall be subjected to 100% radiographic testing (RT).— At set-in flat plates the cylindrical pressure hull shall be ultrasonic tested for lamellar tearing in a way of

the circumferential weld to the flat plate.— Welded joints between reinforcement rings and the pressure hull as well as penetrations at the pressure

hull shall be magnetic particle tested if volumetric non-destructive test methods cannot be applied.

7.3 For carbon and carbon-manganese steel with thickness greater than 30 mm and for alloy steels the non-destructive testing is normally to be carried out not earlier than 48 hours after completion of the welds. Forcarbon and carbon-manganese steels with thicknesses of 30 mm and less the time limit may be reduced to24 hours.

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7.4 All testing shall be carried out by qualified and certified personal according to CG-0051 Metallic Materials -Non Destructive Testing.

7.5 For radiographic testing, x-ray source shall be used whenever possible. Gamma-ray sources may be usedwhen qualified trough examination by the Society.RT may be replaced by ultrasonic testing and vice versa, when methodologically justifiable and in agreementwith the Society. Processing and storage shall be such that the radiographs maintain their quality throughoutthe agreed storage time. The radiographs shall be free from imperfections due to processing.

7.6 For ultrasonic testing the following apply:

— The welded connection in question shall be tested for laminations, transverse and longitudinal defects.— UT shall not be carried out on welds with thickness < 10 mm if not qualified and accepted down to 8 mm.

7.7 For magnetic particle testing the following apply:The object may be directly or indirectly magnetised. AC yoke or prods shall be used. Care shall be takento avoid local heating of the test surface. Prods shall be used for permanent magnets is not permitted.The testing on each area shall be performed with the magnetic field shifted in a least two directionsapproximately perpendicular to each other.

7.8 For penetrant testing the following apply:Colour contrast penetrants shall be used for welds in as welded condition. For smooth (flush grinded welds)fluorescent penetrants may be used. The surface temperature during testing shall be within the temperaturerange 10 – 50°C, if not, a procedure qualification test using ASME comparison blocks shall be carried out.The penetration time shall be at least 15 minutes.

7.9 Testing not described in this section may be required for certain products. In such case the testing standardor procedure shall be accepted by the Society or shall be carried out according to RU SHIP Pt.2 Materials andwelding.

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7.10 Acceptance criteria for welds in pressure hull are specified in the following Table:

Table 2 Acceptance criteria

Testing method Acceptance level

visual testing EN ISO 5817 - level B1)

magnetic particle testing EN ISO 23278 -level 2x

penetrant testing EN ISO 23277- level 2x

radiographic testing EN ISO 10675 –level 1

ultrasonic testing2) EN ISO 11666 – level 2

1) except for imperfection types as follows, for which level C may apply: excess weld metal, excess convexity, excessthroat thickness and excessive penetration

2) all imperfections from which the reflected echo amplitude exceeds the evaluation level shall be characterized and allthat are characterized as planar, e.g. cracks, lack of fusion, incomplete penetrations, shall be rejected.

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