GFI Attachment 1_MODUK Defence Standards.pdf

Defence Standard 02-824 Part 1 Issue 3 Date: 5 November 2013 Amendment 1 Date: 30 January 2014

Copper Nickel Chromium Sand Castings and Ingots Part 1: Production Requirements and Welding

DEF STAN 02-824 Part 1 Issue 3 (Amd 1) ii

Contents Foreword ......................................................................................................................................................vi 1 Scope 2 Warning 3 Normative References 4 Definitions 5 Abbreviations 6 Ingot And Casting Production

6.1 Guide to Production

6.2 Ingots

6.3 Castings

7 Heat Treatment Of Castings 8 Mechanical Property Requirements 9 Non-Destructive Examination Of Castings

9.1 Examination Procedure

9.2 Dimensional Check

9.3 Visual–Optical

9.4 Liquid Penetrant

9.5 Eddy Current

9.6 Radiography

9.7 Evaluation of defects and indications from NDE

9.8 Pressure Tests

10 Rectification of Defects In Castings

10.1 General Guidance

10.2 Rectification of Surface Defects by Blending

10.3 Weld repairs on castings

10.4 Rectification of Dimensional Defects by Weld Deposition

10.5 Rectification of Surface and Sub–Surface Defects by Welding

10.6 Limits on Combined Weld Repairs

10.7 After Welding

10.8 Authority To Proceed With Weld Repair

11 Non-Destructive Examination of Weld Repairs

11.1 Visual-Optical

11.2 Liquid Penetrant

11.3 Radiography

11.4 Dimensional Checks

12 General Welding Requirements

12.1 Introduction

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12.2 Preparation

12.3 Welding

12.4 Post Welding

13 Welding Wire

13.1 Chemistry

13.2 Dimensions and Tolerances

13.3 Condition of Materials

13.4 Test Methods and Acceptance Standards

13.4.1 Analysis

13.4.2 Free Coil and Helix Test (Spooled Wire Only)

13.5 Welding Test

13.6 Non–Destructive Test

14 Weld Procedure Qualification 15 Welder Qualification 16 Identification Markings

16.1 Identification of Ingots

16.2 Identification of Castings

17 Quality Assurance Documentation

17.1 Ingots

17.2 Castings

17.3 Castings requiring qualification

17.4 Welding wire

17.5 Welding

18 Packaging

18.1 Packaging of ingots and castings

18.2 Packaging of welding wire

19 Qualification

19.1 General

19.2 MOD Requirement for Qualification

19.3 Contractors Requirements for Qualification

19.4 The Qualification Process

19.4.1 General

19.4.2 Thickness Examination

19.4.3 Documentation

19.4.4 Stamping of Castings

19.4.5 Records

20 Historical Perspective

20.1 The Copper Nickel Chromium Alloy

20.2 Welding of CuNiCr alloy

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20.3 Properties and performance

21 MOD Sea Technology Group Policy Guidance

21.1 Introduction

21.2 Benefits of Copper Nickel Chromium

21.3 NAG-MT Guidance on the Use of CuNiCr

22 Technical Note Annex A - ECTP 5 – Non-Destructive Test Procedure For The Eddy Current Inspection Of

Copper Nickel Chromium For Surface Discontinuities A.1 Scope A.2 Reference Documents A.3 Personnel Requirements A.4 Area Of Examination A.5 Surface Preparation A.6 Equipment A.7 Calibration Procedure A.8 Examination Procedure A.9 Reporting Of Defects A.10 Rework & Re-Inspection Annex B - ECTP 7 – Non-Destructive Test Procedure For The Eddy Current Inspection Of

Copper Nickel Chromium For Sub-Surface Inspection To Depths Of 10 mm B.1 Scope B.2 Reference Documents B.3 Personnel Requirements B.4 Area Of Examination B.5 Surface Preparation B.6 Equipment B.7 Calibration Procedure B.8 Examination Procedure B.9 Reporting Of Defects B.10 Rework & Re-Inspection Annex C - Procurement Checklist Annex D - Check List For Documents To Be Included In QA Pack For Qualified Castings Annex E - Qualification Certificate For CuNiCr Castings

Figures Figure 1 - Linear Figure 2 - Complex Figure 3 - Through Thickness Defects Figure 4 - Surface Build-Up Test Plate Geometry Figure 6 - Side Bend Test Piece Geometry for Surface Build-Up Procedure v

Figure 7 - Side Bend Test Piece Geometry for Sub-Surface Repair Procedure Figure 8 - Transverse Tensile Test Piece Geometry Figure 9 - All-Weld Tensile Test Piece Geometry

Tables Table 1 - Chemical Composition of Castings Table 2 - Mechanical Properties Table 3 – Chemical Composition of Welding Wire Table 4 - Tolerances on Round Wire Table 5 - Tensile Test Requirements Table 6 - History of specified composition of cast copper nickel chromium alloys Table 7 - History of specified CuNiCr filler wire compositions and consumables used Table 8 - Welding advice and recommended parameters for weld repair of CuNiCr Table 9 - CuNiCr sand casting and ingot properties (based on data sheet previously contained in Def Stan 01-2 Part 2 Section 4, now cancelled) Table 10 - Target Levels for Impurities

Foreword

AMENDMENT RECORD

Amd No Date Text Affected Signature and Date

1 30 Jan 2014 Rectify minor formatting errors, in header and historical record does not affect technical content.

Colin Cockburn, 30 Jan 2014

REVISION NOTE

This standard is raised to Issue 3 to update its content and references.

HISTORICAL RECORD

This standard supersedes the following:

Def Stan 02-824 Part 1 Issue 2 dated 17 October 2005

Def Stan 02-824 Part 1 Issue 1 dated 01 April 2000.

NES 824 Part 1 Issue 3 dated July 1993.

NES 824 Part 1 Issue 2 dated May 1989.

NES 824 Part 1 Issue 1 dated Sept 1986.

Def Stan 02-825 Issue 1 dated 01 April 2000.

NES 825 Issue 2 dated June 1989.

NES 825 Issue 1 dated June 1986.

a) This standard provides requirements and guidance for the management and production of Defence Standards.

b) This standard has been produced on behalf of the Ministry of Defence (MOD) by UK Defence Standardization (DStan).

c) This standard has been reached following broad consensus amongst the authorities concerned with its use and is intended to be used whenever relevant in all future designs, contracts, orders etc. and whenever practicable by amendment to those already in existence. If any difficulty arises which prevents application of the Defence Standard, DStan shall be informed so that a remedy may be sought.

d) Please address any enquiries regarding the use of this standard in relation to an invitation to tender or to a contract in which it is incorporated, to the responsible technical or supervising authority named in the invitation to tender or contract.

e) Compliance with this Defence Standard shall not in itself relieve any person from any legal obligations imposed upon them.

f) This standard has been devised solely for the use of the MOD and its contractors in the execution of contracts for the MOD. To the extent permitted by law, the MOD hereby excludes all liability whatsoever and howsoever arising (including, but without limitation, liability resulting from negligence) for any loss or damage however caused when the standard is used for any other purpose.

vi

Copper Nickel Chromium Sand Castings and Ingots Part 1 - Production Requirements and Welding

1 Scope

This standard provides requirements for the manufacture, inspection and testing of sand castings and ingots in Copper Nickel Chromium (CNC or CuNiCr) alloy. In this issue it also specifies the procedure and requirements for the joining or reclamation by welding of this material (previously contained in Def Stan 02- 825).

2 Warning

The Ministry of Defence (MOD), like its contractors, is subject to both United Kingdom and European laws regarding Health and Safety at Work. All Defence Standards either directly or indirectly invoke the use of processes and procedures that could be injurious to health if adequate precautions are not taken. Defence Standards or their use in no way absolves users from complying with statutory and legal requirements relating to Health and Safety at Work.

3 Normative References

3.1 The publications shown below are referred to in the text of this standard. Publications are grouped and listed in alpha-numeric order.

BS 499-1 Welding Terms and Symbols Part 1: Glossary for welding, brazing and thermal cutting BS EN ISO 4136 Destructive Tests on Welds in Metallic Materials : Transverse Tensile Test BS EN ISO 5173 Destructive Tests on Welds in Metallic Materials : Bend Tests BS EN 1976 Copper and Copper Alloys, Cast Unwrought Copper Products BS EN 1978 Copper and Copper Alloys, Copper Cathodes BS EN 1982 Copper and Copper Alloys, Ingots and Castings BS EN 6892-1 Tensile Testing Of Metallic Materials, Part 1: Method of Test at Ambient

Temperature BS 2M 54 Specification for Temperature Control in the Heat Treatment of Metals DEF STAN 02-729 Requirements for Non–Destructive Examination Methods:

Part 1: Radiographic, Part 3: Eddy Current, Part 4: Liquid Penetrant, Part 5: Ultrasonic DEF STAN 02-747 Requirements for Nickel Aluminium Bronze Castings and Ingots:

Part 2: Nickel Aluminium Bronze Naval Alloy Ingots and Sand Castings with

Welding Permitted to the Wetted Surface, Part 4: Nickel Aluminium Bronze Naval Alloy Sand Castings with Welding

Restricted to the Non-Wetted Surface (Class I and II Castings only) DEF STAN 02-824 Copper Nickel Chromium Sand Castings and Ingots Part 1: Production Methods, Part 2: Guide to Production Methods.

DEF STAN 02-863 Requirements for the Classification, Dimensions, Tolerances and General

Standards of Acceptance for Copper and Nickel Alloy Castings SSP25 Sea Systems Publication No. 25 (SSP25) Quality Assurance for Safety in Submarines

3.2 Reference in this Standard to any normative references means in any Invitation to Tender or contract the edition and all amendments current at the date of such tender or contract unless a specific edition is indicated. Care should be taken when referring out to specific portions of other standards to ensure that they remain easily identifiable where subsequent amendments and supersession’s might be made. For some standards the most recent editions shall always apply due to safety and regulatory requirements.

3.3 In consideration of clause 3.2 above, users shall be fully aware of the issue, amendment status and application of all normative references, particularly when forming part of an Invitation to Tender or contract.

Correct application of standards is as defined in the ITT or contract.

3.4 DStan can advise regarding where to obtain normative referenced documents. Requests for such information can be made to the DStan Helpdesk. Details of how to contact the helpdesk are shown on the outside rear cover of Defence Standards.

4 Definitions

For the purpose of this standard, the definitions shown below apply:

4.1 Approval Authority The organization responsible for approving Weld Procedures. For Weld Procedures produced by a Prime Contractor, MOD (NAG-MT) will be the Approval Authority. For Weld Procedures produced by a sub-contractor, the Prime Contractor will be the Approval Authority. Other arrangements for weld procedure approval may be specified in the Contract.

4.2 Approved Scrap

a) derived from cast copper nickel chromium foundry arisings, the composition of which has been established with regard to the complete range of both the alloying elements and impurity elements, AND

b) segregated and identifiable to the satisfaction of the MOD/Design Authority.

4.3 Cast The product of one furnace or crucible melt, or the product of a number of furnace or crucible melts where such are aggregated and mixed prior to sampling.

4.4 Classification of Castings Each casting is classified according to its service conditions. This is detailed and defined in Def Stan 02-

863. The inspection requirements and welding limitations can differ depending on casting class.

a) Class I

A casting whose failure will lead to uncontrollable flooding, the total immobilization of the ship or submarine or present a serious hazard to personnel.

b) Class II

A casting whose failure will lead to severe but controllable flooding, the serious disruption of weapons systems, main propulsion machinery, or its attendant auxiliaries including generators.

c) Class III

All other castings where their failure will not constitute an immediate significant hazard.

4.5 Contractor The firm, company or organisation working within the scope of this standard

4.6 Design Authority The approved firm, MOD establishment or branch responsible for the detailed design of materiel to approved specifications and authorised to sign a certificate of design or certify sealed drawings.

4.7 Ingots A mass of metal of proportions to suit the Founder’s requirements.

4.8 Interpass Temperature In a multi–run weld, the interpass temperature is defined as ‘the temperature of the weld and adjacent parent metal, immediately prior to the application of the next run’. Interpass temperature is to be measured on the surface of the base material on the side from which welding is to be performed, within 25mm of the weld joint edge.

4.9 Pinpoint Porosity Any circular bleed-out of less than 0.5mm diameter revealed during liquid penetrant examination in accordance with Def Stan 02-729 Part 4.

4.10 Sea Water Wetted Castings Materials Register The Sea Water Wetted Castings Materials Register is the document used to monitor and control the inspection and replacement of First Level Quality Assured NAB and CuNiCr castings which are normally in contact with sea water and are fitted on HM Submarines. This register includes both NAB castings manufactured to Def Stan 02-747 Parts 1, 2 and 4, together with CuNiCr castings manufactured to Def Stan 02-824 Part 1. This register was formerly referred to as the NAB Register, see Def Stan 02-872 Part 1.

4.11 Through Life Records Contractor Contractor contracted to retain and maintain the QA records for all castings contained within the Sea Water Wetted Castings Materials Register through their life.

5 Abbreviations

BS British Standard CNC or CuNiCr Copper Nickel Chromium alloy Def Stan Defence Standard DERA Defence Evaluation and Research Agency DStan UK MOD Defence Standardization Organisation EB Electron beam EC Eddy current ECTP Eddy Current Test Procedure HAZ Heat affected zone HIP Hot isostatic pressing MIG Metal inert gas MOD UK Ministry of Defence NAB Nickel Aluminium Bronze NES Naval Engineering Standard NDE Non Destructive Examination SPC Selective phase corrosion NAG-MT Naval Authority Group – Materials Technology TIG Tungsten inert gas

6 Ingot And Casting Production

6.1 Guide to Production

This CuNiCr alloy has been found to be prone to the formation of thin oxide films during casting that can be entrained within the cast product. This has led to oxide network inclusions and linear defects that have resulted in the rejection of a number of early castings, see clause 20. The formation of this type of defect is related to casting methodology and can be avoided. Def Stan 02-824 Part 2 has been prepared as a guide to production methods for this alloy and has been designed to assist foundries in the consistent production of sound castings.

6.2 Ingots

Ingots for casting stock are to be cast from virgin metals and master alloys as follows:

Nickel To the chemical composition requirements of BS 375 Grade R99.95A or R99.95B but with carbon content less than 0.010%.

Copper To BS EN 1976/BS EN 1978 designation CU-CATH-1.

Manganese 99.9% minimum purity electrolytic manganese flake.

Iron 99.9% minimum purity electrolytic iron.

Silicon High purity lump silicon (0.3% iron maximum).

Chromium 99.5% minimum purity electrolytic or thermic chromium.

NOTE Where thermic chromium is used the aluminium content is to be less than 0.08%.

Titanium Pure titanium in sponge or other solid form, high purity copper- titanium master alloy or high purity nickel-titanium master alloy.

Zirconium High purity copper-zirconium master alloy or high purity nickel- zirconium master alloy.

NOTE Where copper-titanium or copper-zirconium master alloys are used the copper used in the preparation of these alloys is to be high purity electrolytic copper.

The chemical composition of ingots is to be agreed between the ingot manufacturer and the purchaser to ensure that due allowance is made for impurity pick–up during the casting processes.

6.3 Castings

6.3.1 With the exception of minor additions of readily oxidizable elements to compensate for losses during re–melting, only ingots, virgin metals and the manufacturer’s own approved scrap (as defined in 4.2) may be used to produce castings.

6.3.2 No finishing additions such as magnesium or calcium are to be made. No further additions are to be made to a cast after the final analytical sample has been taken.

6.3.3 All ingots used are to be of known quality in accordance with clause 17.

6.3.4 A full chemical analysis is required from a sample piece taken from each cast. The analysis is to conform to the chemical composition specified in Table 1. The analysis of this alloy is to be made using approved analytical standards which are available from NAG-MT, Abbey Wood, Bristol.

6.3.5 To ensure optimum weldability, impurity levels should be kept as low as possible. Refer to clause 22 for recommended tolerances.

Table 1 - Chemical Composition of Castings

Element Per Cent By Weight

Not Less Than Not More Than

Nickel 29.0 32.0

Chromium 1.6 2.0

Iron 0.5 1.0

Manganese 0.5 1.0

Silicon 0.20 0.40

Zirconium 0.05 0.15

Titanium 0.03 0.15

Copper (by difference) Remainder

Impurities

Lead 0.005

Phosphorous 0.005

Bismuth 0.001

Sulphur 0.005

Carbon 0.020

Cobalt 0.050

Boron 0.001

Permitted Total of Impurities - 0.070

7 Heat Treatment Of Castings

7.1 After removal of feeders and running systems by approved methods such as sawing or abrasive wheel cutting, but before any surface grinding, the castings and mechanical test bars are to be ‘Stress Relieved’ according to the schedule set out in 7.2 below. Further stress relieving treatments are mandatory on weld repaired castings (12.4).

7.2 The ‘Stress Relief’ treatment is to be carried out in a furnace that complies with the temperature control guidelines specified in BS 2M 54. The sulphur content of the furnace atmosphere is to be less than 0.005g/m3. The treatment is to consist of heating the casting at a maximum rate of 200°C/hour, to 450- 500°C, holding at this temperature for 1 hour/25mm section thickness (2 hours minimum) and air-cooling.

8 Mechanical Property Requirements

8.1 Tensile tests to BS EN 6892-1 are to be carried out on specimens prepared from test bars made in accordance with BS EN 1982. Test bars are to be taken from the same melt as the castings they represent, and heat-treated in accordance with clause 7. It is advised that three tensile test specimens be made to enable re-tests in the event of failure of the initial test specimen. The tensile test result is to conform to the data given in Table 2.

8.2 Re-tests. Should the original test specimen fail to meet acceptance standards, two further heat-treated specimens from the same cast may be broken in accordance with BS EN 6892-1. Both additional tensile test results are to conform to Table 2.

Table 2 - Mechanical Properties

Tensile Strength 0.2% Proof Stress Elongation

(MPa) (MPa) (Per Cent)

≥480 ≥300 ≥18

NOTE The mechanical properties of actual castings may fall below the minima values quoted for test bars in the above table. All design calculations must take this into consideration. Please refer to 20.3 for further information.

9 Non-Destructive Examination of Castings

9.1 Examination Procedure

Reference diagrams according to Def Stan 02-863 are to be provided by the purchaser for all Class I and Class II castings to show Critical Test Regions and Test Regions which are to be considered in non– destructive examinations (NDE).

9.2 Dimensional Check

9.2.1 All castings are to be fully dimensionally checked, where practicable, to ensure that drawing requirements are met, or are otherwise in accordance with Def Stan 02-863. Depending on accessibility, thickness measurements may be made by direct measurements, dial calliper gauges or ultrasonics.

9.2.2 Ultrasonic thickness readings, regardless of accessibility for mechanical measurements, are to be carried out in Critical Test Regions and are to be in accordance with Def Stan 02-729 Part 5. The Critical Test Regions are to be surveyed for compliance with maximum/minimum wall thickness.

9.2.3 Ultrasonic equipment should be calibrated on a known thickness of the castings being inspected, or the time base should be set up on a steel block and readings converted via a calibration curve for Def Stan 02-824 specification CuNiCr material. (Velocity of sound in this CuNiCr alloy is nominally 5200 ms-1).

9.3 Visual–Optical

9.3.1 All castings are to be 100% visually inspected, assisted where necessary, by the use of x5 magnification optics. All imperfections are to be identified and recorded.

9.3.2 The finished condition of all surfaces is to be clean and free from cracks or linear defects exceeding the limits in 9.7.

9.3.3 The surface finish is to meet the standard specified in the contract documents and drawings.

9.4 Liquid Penetrant

9.4.1 A 100% liquid penetrant examination is to be carried out on all Class I and Class II castings before any machining operations are commenced to prevent nugatory work.

9.4.2 A 100% liquid penetrant examination, in accordance with Def Stan 02-729 Part 4, is to be undertaken on all surfaces of Class I and Class II castings with the surfaces examined in their finished condition.

9.4.3 For Class III castings a liquid penetrant examination is to be conducted on a batch basis as stipulated by the purchaser. If no specific batch test requirement is stipulated then the minimum requirement shall be one casting from any batch of similar castings ordered. The Class III castings for examination are to have a 100% liquid penetrant examination, in accordance with Def Stan 02-729 Part 4, to be undertaken on all surfaces examined in their finished condition.

9.4.4 Indications are to be evaluated against the criteria detailed in 9.7.

9.5 Eddy Current

9.5.1 A 100% eddy current (EC) surface and sub–surface examination is to be carried out on all Class I and Class II castings before any machining operations are commenced to prevent nugatory work.

9.5.2 A 100% surface and sub–surface eddy current examination is to be undertaken on all surfaces of Class I and Class II castings with the surfaces examined in their finished condition.

9.5.3 The eddy current inspection is to be carried out in accordance with MOD approved inspection procedures (ECTP 5 and ECTP 7, see Annexes A and B to this document) and comply with Def Stan 02-729 Part 3.

9.5.4 Oxide inclusions/discontinuities identified by surface eddy current examination are not acceptable in sealing areas. However, these may be recovered by weld repair in accordance with 10.5. Other areas are to be evaluated in accordance with 9.7.

9.5.5 Oxide inclusions/discontinuities identified by sub–surface eddy current examination up to a maximum depth of 10mm below each surface are to be noted. Single indications are to be recorded as being a discontinuity of a size equal to the diameter of the probe. Larger, continuous discontinuities are to have their positions plotted. The discontinuities are then to be evaluated in accordance with 9.7.

9.6 Radiography

9.6.1 Critical Test Regions and Test Regions in Class I and Class II castings are to be subjected to 100% radiographic examination in accordance with Def Stan 02-729 Part 1.

9.6.2 Non-designated regions in Class II and Class III castings may have radiographic examination requirements. In certain circumstances examination by radiography on a sample basis may be specified by contract or drawings to establish that a satisfactory general quality of product is being supplied. Typical examples are:

a) Lowly stressed Class II castings.

b) Sample positions on large Class II or Class III castings.

c) Batch supply of Class III castings.

9.6.3 All sub–surface imperfections are to be identified for subsequent assessment in accordance with the acceptance standards defined in Def Stan 02-863 and 9.7.

9.7 Evaluation of defects and indications from NDE

9.7.1 Surface, surface-breaking or near-surface defects or indications will be identified by visual-optical, liquid penetrant and eddy current examinations conducted on the casting. Sub-surface defects or indications will be identified by eddy current and radiographic examinations conducted on the casting. The significance of these defects or indications needs to be evaluated and their acceptability assessed.

9.7.2 General standards of acceptance are specified in Def Stan 02-863. Specific acceptance standards exist for this particular CuNiCr material and are detailed below. There may also be instances where machined surfaces of castings manufactured to this standard require more stringent acceptance standards than those specified in these documents. Where necessary, this requirement is to be clearly stated in the contract documents and is to be the subject of discussion between the purchaser and the contractor prior to manufacture of the castings.

9.7.3 Indications of chain–like porosity and surface (or near-surface) oxide inclusions in linear formations are to be evaluated as follows:

a) The permissible length of any single indication is not to exceed the finished drawing wall thickness (t). On flanges t is to be taken as the flange thickness.

b) The length of a defect is defined as the maximum size of the major axis of the defect.

c) For assessment purposes all discontinuities less than 0.1t in length can be ignored, except when a discontinuity, found by eddy current inspection, has a variable amplitude response, when it’s total length is to be assessed by its maximum response.

d) Adjacent discontinuities are to be assessed by the following means to determine if they should be regarded as being a single, larger discontinuity:

1) The lengths of the two discontinuities are to be averaged. If the distance between the two discontinuities is greater than the average length of the discontinuities they can be considered independent.

2) If the distance between discontinuities is equal to or less than the average length of the discontinuities then they are to be considered as one discontinuity, the size of which is taken to be the overall length or the major axis of the discontinuities including the distance between them.

3) The composite discontinuity is acceptable provided it’s length is less than or equal to t mm.

4) The composite discontinuity is to be assessed to determine if any further discontinuities are interacting with it using the same procedure.

Examples are given in Figure 1 and Figure 2.

Figure 1 – Linear

Figure 2 – Complex

9.7.4 Indications arising from porosity and surface oxide inclusions in non–linear formations are to be assessed as follows:

a) Pinpoint porosity is acceptable except in areas where sealing of a housing against a running shaft is required, e.g. pump glands, propeller shaft seals etc, and in flexible couplings.

b) Bleed-outs larger than pinpoint and other non-linear defects are acceptable provided that:

1) The maximum size of any indication is not to exceed 5mm diameter bleed-out, AND

2) The sum of the diameters of all indications in an area of 70 x 70mm is not to exceed 24mm.

NOTE The indications identified in 9.7.4 are acceptable providing that the immediate area of the casting is acceptable when examined for sub–surface defects.

9.7.5 Through–casting defects are not permitted. Where material thickness prevents through–casting measurement, then defects on opposite sides of a section are deemed to be through–casting when less than or equal to (a + b)/2 apart. See Figure 3.

9.7.6 Castings with unacceptable defects or indications may be recoverable using rectification procedures detailed in clauses 10 & 11 of this standard.

Figure 3 - Through Thickness Defects

9.8 Pressure Tests

When stated in the contract the castings are to be subjected to the specified water pressure test for a minimum period of 15 minutes. Certain castings may require longer periods of pressure testing. When necessary this will be specified in the contract. Each casting is to show no evidence of leakage.

10 Rectification of Defects In Castings

10.1 General Guidance

10.1.1 Foundries producing castings in accordance with this Def Stan should employ production methods that minimise or eliminate the occurrence of unacceptable defects. Def Stan 02-824 Part 2 provides guidance on production methods for this alloy to assist foundries. Repair of surface (or near-surface) defects may be carried out either by blending or weld repair in accordance with clauses 10.2 or 10.5 respectively.

Blending is the preferred method of repair. Weld repair of this alloy is possible in most cases using confirmed procedures and skilled execution but it is not desirable to have weld repairs. Hence, weld repair should only be carried out where blending is not possible.

10.1.2 Any casting may be rejected for defects discovered during subsequent machining notwithstanding that the casting had been passed previously as conforming to this standard.

10.2 Rectification of Surface Defects by Blending

10.2.1 Blending to remove surface (or near-surface) defects is an acceptable rectification process, within the limitations detailed below. Blending out of these surface defects is preferable to weld repair whenever possible. However, rectification by blending is not permitted where this encroaches on any bearing or sealing surface.

10.2.2 Unacceptable surface defects may be excavated by an approved process (such as machining or pneumatic chipping and grinding) providing the resulting depression does not reduce the contract drawing section thickness by more than 5mm or 10%, whichever is the least, (i.e. 10% on section thicknesses up to 50mm, and 5mm on thicknesses over 50mm).

10.2.3 The excavation must be smooth and all sharp edges are to be removed. The depression sides and ends are to be smoothly blended out by a minimum radius of three times the maximum depth of blending and the edge formed with the surface is also to be faired smooth. The remaining section thickness in way of the depression is to be free from sub–surface defects in Critical Test Regions and Test Regions. The total area subjected to blending, including the area affected by the fairing, is not to exceed 10% of any designated region or 20% of any non-designated region in which the defect is situated.

10.2.4 In some instances extensive blending of surface defect excavations is unnecessary, and where approval is granted from the relevant Design Authority, an excavation prepared in accordance with 10.2.2 may be acceptable without carrying out the operations described in 10.2.3.

10.2.5 If the full dimension checks specified in 9.2 were conducted before blending, then wall thickness measurements must be repeated on the areas blended. Results are to be documented and included in the QA documentation set.

10.3 Weld repairs on castings

10.3.1 Under this issue of this standard the rectification by welding is permitted on all surfaces, including wetted surfaces and sealing faces, subject to 10.8. However, it should be appreciated that the extent of excavations and subsequent weld repair is to be only that necessary to bring the casting within the specified acceptance standards. The extent of weld repair is to be limited as stated below.

10.3.2 All permitted weld repairs are to be carried out using MOD approved weld procedures and qualified welders, see clauses 12, 13, 14 & 15 of this Standard.

10.4 Rectification of Dimensional Defects by Weld Deposition

10.4.1 Correction of casting dimensions and machining errors may be made by weld deposition using an approved procedure.

10.4.2 The weld repair shall be within the following limits:

a) Weld deposition thickness to be restricted to a maximum of 10mm.

b) The area of weld deposition in Critical Test Regions and Test Regions is to be restricted to 10% of the inner or outer surface area of the region, not including flange thicknesses and webs.

c) The area of weld deposition in non–designated regions is to be restricted to 20% of the inner or outer surface area of the region, not including flange thicknesses and webs.

10.5 Rectification of Surface and Sub–Surface Defects by Welding

10.5.1 Unacceptable surface (or near-surface) defects which cannot be blended out within the limitations of 10.2, and unacceptable sub-surface defects, may be repaired by welding subject to the limits and authority detailed in this standard.

10.5.2 The weld repair shall be within the following limits:

a) Weld deposition thickness to be restricted to a maximum of 10mm.

b) The area of weld deposition in Critical Test Regions and Test Regions is to be restricted to 10% of the inner or outer surface area of the region, not including flange thicknesses and webs.

c) The area of weld deposition in non–designated regions is to be restricted to 20% of the inner or outer surface area of the region, not including flange thicknesses and webs.

10.6 Limits on Combined Weld Repairs

10.6.1 The total area of weld repairs from all causes, e.g. dimensional correction, surface and sub–surface defects is to be within the following limits:

a) In Critical Test Regions and Test Regions, to be restricted to 10% of the inner or outer surface area of the region, not including flange thicknesses and webs.

b) In non–designated regions, to be restricted to 20% of the inner or outer surface area of the region, not including flange thicknesses and webs.

c) In Class I and Class II castings, not to exceed 10% of the total surface area of the casting, excluding flange thicknesses and webs.

d) In Class III castings, not to exceed 20% of the total surface area of the casting, excluding flange thicknesses and webs.

10.6.2 When repairs are required which are more extensive than permitted by the above clauses then the casting is to be either scrapped, or a Production Permit submitted which defines the extension of weld repair beyond the permitted limits and clearly explains the reasons why such repairs are necessary.

10.7 After Welding

10.7.1 After all weld repairs have been completed the casting is to be re–heat treated in accordance with 7.2.

10.7.2 After heat treatment all castings that have been weld repaired are to be inspected as detailed in clause 11 below.

10.8 Authority To Proceed With Weld Repair

10.8.1 The authority to proceed with weld repair is as follows:

a) Minor functional repairs, i.e. those falling within the dimensional limits set out in this Def Stan, may be carried out without reference to the Design Authority.

b) Major repairs falling outside the permitted limits set out in this standard require a Production Permit to be submitted to the Design Authority for approval to proceed. These will only be given in exceptional circumstances. Production Permit submissions for consideration are to include:

1) A clear explanation as to why such repairs are necessary.

2) Full details of the proposed method of repair including the approved welding procedure(s) to be used and confirmation that the weldability test defined in this standard has been satisfactorily completed.

3) Sketches of the proposed repair indicating the position, nature, extent and depth of defects, design wall thickness of the area and thickness of the original parent material remaining.

NOTE Contractors will need to be aware of the possibility of minor repairs drifting into the Production Permit category resulting in nugatory work and expenditure.

11 Non-Destructive Examination of Weld Repairs

11.1 Visual-Optical

11.1.1 The surfaces of all welds are to be inspected visually before any other means of non–destructive examination. Visual aids such as magnifying lenses (x10) and strong lights are to be used to quantify defects. All imperfections are to be identified and recorded.

11.1.2 The welds and adjacent parent material are to be free from scale, slag, weld spatter and arc strikes.

The weld is to be of regular surface appearance, i.e. free from globular deposits and sharp discontinuities and surface breaking porosity. Edges of welds are to blend smoothly and gradually into the parent material.

The depth of local undercut or depression resulting from blending is not to exceed 1mm.

11.2 Liquid Penetrant

11.2.1 All weld repair and weld build–up areas are to be examined in accordance with the procedures defined in Def Stan 02-729 Part 4. Examinations are to be conducted after grinding or machining the weld surfaces to the required profile. The welds and adjacent material are to meet the acceptance standards defined in 9.7.

11.3 Radiography

11.3.1 All weld repairs are to be radiographed in accordance with the procedures defined in Def Stan 02- 729 Part 1 and adherence to this standard is of particular importance. It is preferred that X-Ray is used wherever practicable. All sub-surface imperfections are to be identified for assessment.

11.3.2 General standards of acceptance are specified in Def Stan 02-863. Specific acceptance standards exist for welds in this particular CuNiCr material and are detailed below.

11.3.3 Cracks and lack of fusion defects are not acceptable.

11.3.4 The maximum length of any single linear inclusion in the weld repaired region is not to exceed one half of the design wall thickness in way of the inclusion.

11.3.5 Discrete inclusions are to be separated by at least 2.25 times the contract drawing section thickness of the casting in way of the defect; or 1.25 times the length of the larger adjacent defect, whichever is the greater. If however the distance between the ends of two defects or defective areas is less than either of the above values, they are to be considered as a single defect showing an overall length equal to the distance measured between the two extremities of the defects or defective areas and which includes the area between.

11.3.6 The total length of inclusions in the weld region is not to exceed 20% of the maximum dimension of the area affected by the weld repair.

11.3.7 Loss of wall thickness from localised internal porosity is not to exceed 5% of the designated wall thickness in Critical Test Regions and 10% in Test Regions and non–designated areas.

11.4 Dimensional Checks.

11.4.1 After the completion of welding and any subsequent surface dressing it is necessary to conduct dimensional checks on the weld repaired areas. These check are to be conducted in a similar manner to that specified in 9.2. Records are to be retained within the QA documentation set.

12 General Welding Requirements

12.1 Introduction

12.1.1 The necessity for the existence of a Standard for the welding of this CuNiCr alloy was originally associated with the potential need to repair castings containing unacceptable casting defects or requiring recovery from machining errors. There have been no mechanical or corrosion performance issues associated with weldments in this alloy. It is therefore possible to conduct full thickness weldments provided these are acceptable to the Design Authority. All welding must be conducted using a suitable approved welding procedure and conducted by a suitably qualified welder (see clause 14). Weld repair to recover ex-service components may also be acceptable to the Design Authority, particularly when within the limitations stated in this Standard for new components.

12.2 Preparation

12.2.1 Defects are to be removed by machining or pneumatic chipping and grinding. Excavation of defects is to commence in sound material at the ends of the defects and proceed from each end towards the centre.

Excavations are to be finished smooth, tapered at the sides and rounded at the bottom to facilitate full access for the root run and correct manipulation of the filler wire. A boat shaped contour that provides suitable access for efficient weld repair is advised. A width to depth ratio of at least two is recommended.

12.2.2 It is essential to confirm the complete removal of defects from the area of the weld repair. Before weld action is undertaken a thorough examination of the excavated area is to be made using radiography and liquid penetrant methods to ensure complete removal of the defect. Eddy current testing may also be considered to confirm the removal of oxide inclusions if probe access is possible.

12.2.3 The welding surfaces and adjacent area must be clean and free from oxide skin produced during casting and/or heat treatment. Prior to the deposition of weld material, all contaminants resulting from non– destructive examination are to be removed with lint-free cloth using acetone or the approved solvent remover for the liquid penetrant system used.

12.3 Welding

12.3.1 Arc welding is to be carried out with TIG, MIG, Pulsed MIG or a combination of these procedures.

All welding is to be carried out in the ‘Flat Position’ in accordance with the definitions given in BS 499-1.

12.3.2 Welding consumables should be selected in accordance with the requirements of clause 13.

Approval for the use of any consumable that does not fully comply with clause 13 should be obtained from the Approval Authority prior to use. All welding consumables are to be readily identifiable so that they can be positively related to the Quality Assurance documentation.

12.3.3 In order to achieve satisfactory results it is essential that the instructions and recommendations detailed in this standard are considered in all repairs to castings, and are suitably incorporated into the appropriate weld procedures.

12.3.4 It has been found that welding using a buttering technique to initially clad the surface of the excavation and then a shingling technique for the filler runs produces the best welds. The final tying-in weld run at each level should be centrally placed. Some recommended welding parameters for this CuNiCr alloy based on previous experience are given in Table 8 for guidance.

12.3.5 Stop and start porosity or deep end craters are to be minimised by use of the ‘run back technique’ as appropriate to the welding process being used. This technique is a means of avoiding porosity and crater cracking which can be caused by the abrupt withdrawal of the welding arc at the end of a weld run. This technique consists of delaying the consumable at the weld end to fill the crater and then welding back along the top of the previously deposited weld for a short distance, thus facilitating the withdrawal of the arc from superfluous weld metal which is subsequently removed.

12.3.6 Where necessary, extension ‘run–on’ and ‘run–off’ plates of the same material as that to be welded are to be securely welded to the component and grooved to conform to the actual weld preparation. For the repair of excavations wedge shaped ‘run–on’ and run–off’ plates may be used.

12.3.7 When large areas of weld repair are involved, the weld metal is to be deposited in such a manner that the final weld pass consists of weld metal to weld metal.

12.3.8 Interpass cleaning is to be carried out using a stainless steel wire brush that has not been used on any other material.

12.3.9 Interpass grinding may be necessary to achieve a good weld profile with adequate fusion onto the preceding weld bead. Interpass grinding may also be required to remove any slag lines. All interpass grinding is to be carried out with resin bonded alumina grinding wheels or with tungsten carbide burrs.

12.3.10 Interpass temperature is to be determined by contact pyrometers or thermocouples. The use of low melting metallic alloys or any temperature indicating crayons or paints is prohibited. The interpass temperature during welding is not to exceed 150°C.

12.3.11 Electron beam (EB) welding of this alloy is considered a suitable technique for full thickness weldments. However, the use of this technique needs the approval of the Design Authority before use. This Standard does not specifically cover the special requirements of this welding technique. Weld procedures are to be prepared and qualified in accordance with clause 14, or as closely as possible. It is essential that adequate properties are demonstrated using a particular weld procedure and the design of the component using EB weldments does not compromise the shock requirements.

12.4 Post Welding

12.4.1 After all weld repairs have been completed the casting is to be re–heat-treated in accordance with 7.2.

12.4.2 After heat treatment all castings that have been weld repaired are to be inspected as detailed in clause 11.

12.4.3 If a casting repair is initially unsuccessful and the ‘repair’ requires rewelding, not more than two reweldings are permitted.

13 Welding Wire

13.1 Chemistry

Table 3 – Chemical Composition of Welding Wire

Element Per Cent By Weight

Not Less Than Not More Than Nickel 29.0 32.0

Chromium 2.0 a (see note below) 2.4

Iron 0.0 1.0

Manganese 1.4 a (see note below) 2.0

Silicon 0.20 0.40

Zirconium 0.05 0.15

Titanium 0.03 0.15

Copper (by difference) Remainder

Impurities

Lead 0.0015

Phosphorus 0.005

Bismuth 0.0005 a (see note below)

Sulphur 0.003

Carbon 0.006

Cobalt 0.020

Boron 0.001

Selenium 0.0005

Tellurium 0.0005

Arsenic 0.0010

Zinc 0.0020

Permitted Total of Impurities 0.060 a NOTE: All new wire procurements should meet the above composition. However, to permit the use of the research batch of Turbaloy 67 (MOD) consumable in service welds in the interim there is a temporary concession on some compositional limits (Chromium 1.85 min, Manganese 0.76 min and Bismuth 0.001 max) (see Table 7).

Welding wire is to conform to the chemical composition detailed in Table 3. Wire is to be drawn from ingots or billets that have been produced in a vacuum induction furnace from virgin metals or master alloys as specified in 6.2.

13.2 Dimensions and Tolerances

13.2.1 The diameter of the wire is to be determined by means of a suitable micrometer. The diameter is defined as the mean of two measurements taken at right angles made at the same cross-section of a sample taken from any part of the spool or, when supplied in one metre lengths, any position on a random sample from each batch.

13.2.2 The difference between the maximum and minimum measurements, taken at the same cross-section is not to exceed the amounts specified in Table 4.

Table 4 - Tolerances on Round Wire

Specified Diameter (mm)

Over Up to and including

Tolerance (mm)

Difference between max and min measurements not to exceed (mm)

0.7 2.00 +0.01 -0.04 0.02

2.00 5.00 +0.01 -0.07 0.02

13.3 Condition of Materials

a) All reeled wire is to be supplied in a cold drawn condition suitable for use in standard MIG Welding Equipment. If during manufacture the wire is fully annealed, attention is drawn to the material’s ductility trough in the 550°-750°C temperature range.

b) There are to be no joints in the wire.

c) The wire is to be supplied in a clean condition with the oxide layers removed by a mechanical process such as diamond shaving or a chemical etching process.

d) The wire is to be free from oil, dirt, grease, chemical contamination or other foreign matter that would adversely affect the quality of the weld.

e) The wire is to be supplied in one metre straight lengths for rod or on spools with the wire precision layer wound. The size of the spool is to be 300mm diameter or as agreed for each contract of supply.

f) Spooled wire is to be closely wound in layers so that it is free from kinks, waves or sharp bends and can be unwound without restrictions caused by overlapping or wedging. The outside end of the wound wire is to be securely fastened at a readily located point.

g) Each batch of wire is to be given a unique number that relates it unambiguously to the extrusion billet from which it was manufactured. Only one extrusion billet is to be used for each batch of finished wire.

13.4 Test Methods and Acceptance Standards

13.4.1 Analysis

A full analysis is to be made from a sample of the finished wire from each batch and results recorded. The chemical analyses are to conform to Table 3. Any wire failing to meet the chemical composition detailed in Table 3 is to be rejected together with all other wire from the same batch.

13.4.2 Free Coil and Helix Test (Spooled Wire Only)

A length of wire sufficient to form at least a 1⅛ loop is to be cut and removed from a spool of wire taken at random, to represent the batch. The wire is to be allowed to freely unwind from the spool without any undue effort being applied so that it forms a free coil. The coil is to be placed on a flat surface and the diameter and pitch (vertical wire separation) recorded. For 300mm diameter spools the diameter of the coil is to be 380mm minimum and 760mm maximum with vertical separation of the wire (pitch) is not to exceed 25mm.

For other sizes of spools the dimensional limitations are to be as stated in the Contract for supply.

13.5 Welding Test

Each batch of wire, spooled or straight lengths, is to be tested for weldability by using a random sample of wire, to represent the batch. The wire is to be deposited on a 70/30 copper-nickel plate of approximately 12mm thickness so that three beads, each 100mm long, are laid parallel to each other, the third bead being superimposed over the other two beads. The test weld is to be radiographed and examined in accordance with Def Stan 02-729 Part 1, and is to be free from indications of porosity, cracking or inclusions.

13.6 Non–Destructive Test

The surface of the wire is to be examined, under clean conditions, in the supplied condition before sealing and packaging. Any indications of oxides, staining, variations in colour or surface roughness are to be recorded. The wire is to be rejected if there is any evidence of discoloration, surface roughness, oxide, scale, grease, oil or any loose contamination. The outside end of each spool of wire and one straight length from each package are to be dimensionally checked and the results recorded. The dimension of the wire is to be within the tolerances stated in Table 4, and to the diameter specified in the Contract Documents.

14 Weld Procedure Qualification

14.1 All welding is to be carried out to approved welding procedures for each welding process or combination of welding processes concerned. Weld procedures, complete with the test results, are to be submitted to the Approval Authority for approval prior to use.

14.2 Written weld procedures are to be prepared embodying the relevant information from this standard and are to include all information required to complete sound welds, including the following:

a) Parent Material identity and size.

b) Welding Process or combination of welding processes.

c) Welding Process Parameters, as follows:

1) Welding position;

2) Welding consumables, identity and specification;

3) Sketch of weld preparation;

4) Welding characteristics including…