Indian Institute of Welding ANB Refresher Course module 16

Quality Assurance of Welded Structures

Content

Concept of Quality Assurance & Quality Control A Brief Discussion on ISO 3834 Inspection of Welds WPS,PQR & WPQ- A Brief Discussion Comparison Between ASME Sec. IX and ISO 9606 Weld quality and defects Limits of weld defects as per ISO 5817 Testing of Welds Visual Testing VT- its Criteria as per AWS D 1.1 and BS 5289

Concept of QA & QC Some DefinitionsQuality- The totality of features and characteristics of a product or service that bear on its ability to satisfy stated and implied needs. Quality Management- That aspect of overall management functions that determines and implement Quality System & Policy. Quality System- The organisational structure, responsibilities, procedures, processes and resources for implementing Quality Management. Quality Assurance- All those systematic actions necessary to provide adequate confidence that a product or service will satisfy given requirement for quality.

Concept of QA & QC Some DefinitionsQuality Control- The operational techniques and activities that are used to fulfill requirements for quality. Quality Document- All necessary papers required to produce Quality Product/Service duly approved by respective authorities. Quality Records- All necessary papers to demonstrate the achievement of required quality and the effective operation of the quality system. Quality Plan- A document setting out specific quality practices, resources and sequence of activities relevant to a particular product, service contract or project.

QUALITY ASSURANCE & QUALITY CONTROL OF WELDING

QualityFitness for purpose or use. Conformance to specified requirements. The totality of features & characteristics of a product or service that bear on its ability to satisfy the stated and/or implied needs. Degree to which a set of inherent characteristics fulfils requirements.

Quality

New definition

Meeting & anticipating customers requirements, stated or implied. At a given time & over a period of time. At a price the customer can afford and is willing to pay. Introducing new & better product s into the market faster than competitor. Continuously bringing down the cost of manufacturing.

Quality

Quality of a Product (or Service) is not what you put in to it; it is what the Customer gets out of it.

QualityREQUIREMENTS : Need or expectation that is stated, generally implied or obligatory. GRADE : Category or rank given to different quality requirements for products, processes, or systems having the same functional use .

QualityCUSTOMER SATISFACTION :

Customers perception of the degree to which the customers requirements have been fulfilled.SYSTEM : Set of interrelated or interacting elements. MANAGEMENT SYSTEM : System to establish policy and objectives and to achieve those objectives. QUALITY MANAGEMENT SYSTEM : Management system to direct and control an organization with regard to quality.

QualityAssurance: The act of giving confidence, the state of being certain or the act of making certain. Quality assurance: The planned and systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled.

QualityControl: An evaluation to indicate needed corrective responses; the act of guiding a process in which variability is attributable to a constant system of chance causes. Quality control: The observation techniques and activities used to fulfill requirements for quality.

Quality

- Customer focus

Organizations depend on their customers and therefore shall:1. Understand customer needs and expectations Current & future needs 2. Meet customer requirements 3. Strive to enhance customer satisfaction

Quality

-

Defect

Anything that dissatisfies the Customer (internal or external)

Quality

- Customer focus

Customer requirements are dynamic Lower the Defects

1. Lower Cycle time (Delivery in time) 2. Lower Cost of production 3. Higher Customer Satisfaction 4. Higher People Satisfaction 5. Higher Profits

Quality

- Customer focus

Two important questions: 1. Who are the customers? 2. What does it take to satisfy them?

Qualityapproach

- Sequence of

Inspection Call from shop or fabricator Ensuring availability of Quality Plan, Quality Control Procedures, Gauges (calibration) etc. Verification of Purchase Orders Verification of Dimensional Report w.r.t Purchase Order, Approved Drawing

Qualityapproach

- Sequence of

Verification of raw material TCs Performing - Visual Examinations Ensuring - Job Identification details Dimensional Check Conducting LPI, MPI, RT / UT as applicable. Confirming 1. LPI, MPI, RT / UT results. 2. Heat Treatment details 3. Verification of Heat Treatment Charts and job correlation.

Quality

- Sequence of approach

Ensuring before External Inspection / Dispatch Surface Protection-Painting(DFT) Work Order Details, Color Code VCI Pellets, End Capping Final Clearance by Third Party Inspection Agency / IBR

Quality

- Document

VerificationFirm / Product Approvals WPS/PQR ,Welder Qualifications Purchase Order Quality Plan / Quality Control Procedure Painting Schedule Work Order, Drawings, Design Changes / Non Conformances Report Raw material / Pipes Test Certificate

Quality

- Document

VerificationLab Test Reports NDE (LPI/MPI/RT/UT) Reports Heat Treatment Reports List of approved vendors for Electrodes / Paints / NDE consumables List of approved service agencies for Lab Testing, NDT, Heat Treatment

Quality

- Prior to Fabrication

Drawings & Specifications Selection of Welding Process Material Specification & Inspection Inspection of consumables Welding Procedures Welding Equipments Welder Qualifications Testing Facilities

Quality

- During Fabrication

Inspection of prepared material Edge Preparation, surface condition etc. Assemblies Fit up, Root gap, position, orientation etc. Welding Consumables E 7018, E 7018-A1 etc. Operators Qualification, Position, sequence etc. WPS Conformance

Quality

- After Fabrication

Visual Inspection a) Surface Defects: Blow Holes, Porosity, Unfilled Crater, Un-fused welds b) Surface Cracks c) Damaged to parent metal: Undercut, Burning, Overheating d) Profile Defects:- Overlap, Excess penetration, Incomplete penetration

Quality

- After Fabrication

e) Incorrect Finish:Ripple Mark Weaving Faults Chipping & Peening marks Spatter Inspection of Weld Dimensions Fillet, Throat size. Mech.Testing:- Test Coupons, Results. NDE

QualityRegister

- Records

Purchase Order Material Receipt / Account Raw material Test Certificates Welders Log Book NDE, Heat Treatment Inspection ( Internal / TPI / IBR ) Audit Reports ( Internal / External )

QualityQuality is better defined as Error free or Defect free performance. Do the right things right the first time and every time.

Welding DefectsSmall imperfections which affects the property of the weld metal are called discontinuities

When the discontinuty is large and affect the function of the joint is termed as defect.

Defects

A. External defects B. Internal defects C. Both internal&external defects

External defects1. 2. 3. 4. 5. 6. Undercut Cracks Blowhole and porosity Slag inclusions Edge of the plate melted off Excessive convexity/oversized weld/ Excessive Reinforcement 7. Excessive Concavity/Insufficient Throat thickness/ Insufficient fill

Contd1. Incomplete Root penetration /Lack of penetration 2. Excessive Root penetration 3. Overlap 4. Mismatch 5. Uneven/Irregular bead appearance 6. Spatters

Internal defects1. 2. 3. 4. 5. 6. Cracks Blowhole and porosity Slag Inclusions Lack of fusion Lack of Root penetration Internal stresses or locked-up stresses (or) Restrained joint

Both External And Internal Defects1. 2. 3. 4. 5. Blowhole Slag inclusions Lack of penetration (fillet weld) Cracks porosity

Dimensional defects Distortion Incorrect Joint Penetration Incorrect Weld Size Incorrect Weld Profile

Structural discontinutiesPorosity Slag Inclusion Under cut Incomplete fusion Incomplete penetration Crack Surface defects

Faulty weld size and profileBUTT JOINT Lack of Reinforcement Excessive Reinforcement Irregular Profile FILLET WELD Insufficient Throat Insufficient Leg Length Excessive Convexity(or)Concavity Unequal Leg Lengths Irregular Weld Face

CrackDiscontinuty caused by the tearing of the metal Hot crack Cold crack Crater crack

Crater cracksLongitudinal Crater crack (may(or)may not extend to the base metal) Transverse Crater crack Star crater crack

PorosityGroup of gas pores in a weld due to entrapment of gas during solidification is termed as porosity. Porosity: small spherical cavities either clustered locally (or)scattered Blow hole: single large cavity piping (or)warm holes: Elongated (or) tubular gas cavities

ReasonContamination of the base metal Moisture in the electrode Improper arc length Excessive current High travel speed

Slag inclusionEntrapment of slag or Non- Metallic inclusion incomplete deslagging of a previous pass. Excessive weaving. (slag solidity at the sides of the bead) Improper travel speed Excessive amount of slag ahead of the arc.

Remedies Proper cleaning of slag Restrict the width of the weaving(width of slag immediately behind the weld puddle remains molten.

Weld spatterAt the conclusion of a weld small particles (or) globular of metal may sometime be observed scattered around the vicinity of the weld.this is known as spatter. Reason Arc blow:(making the Arc uncontrollable) 1. Too long an arc 2. An excessive

Under cut Continues or discontinues groove at the toes of the weld pass and is located on the base metal. Excessive current High travel speed Improper electrode angle. Improper electrode size

Incomplete Penetration Failure of weld metal to reach and fuse the root of the joint. Reason : Less bevel angle High welding speed Low current Large dia electrode Insufficient Root gap Improper Electrode angle

Controlling factors1. Proper travel speed 2. proper parameters a.current b.voltage c.flow rate 3.proper edge preparation a.Angle b.Root gap

Contd4.suitable diameter of electrode 5.Base metal preparation 6.Baking of electrode

DocumentationManual- Strategic Type, Top Management Function Procedure- Tactical Type, Departmental Function Work InstructionOperational Type, Supervisory Function Records- Specific Type, Related to all Function

QUALITY PLAN FOR MANUFACTURING / INSPECTION ACTIVITY Test Type Agency Column Importance Type MA = Major P = Test / Inspection to be performed 1= Customer CR = Critical W = Test / Inspection to be Witnessed 2 = Organization MI = Minor V = Verification of Documents/Test Records 3 = Consultant / Inspection AgencyAgencyS l . N o

Item Description. / Operation

Characteristics Checked

Catego ry

Type Method of Check

Extend of Check

Reference Document

Acceptanc e Norms

Format of report

Remarks P W V

1 .

RAW MATERIAL S Plate Rounds

Chemical & Physical Properties Internal Flaws Chemical Properties only

MA MA MA

Verificatio n U. T. Verificatio n

1 / Heat 100% 100%

Order / Specificati on Order / Specificati on Drawing

Drg.Spec. Drg. Spec. Drg. Spec.

MTC Lab Report Lab Report Lab Report

2 2 2

1 3 1 3 1 3

UT for Plates >12 mm thick

2 .

FORGINGS

Chemical Properties Dimensions

MI MA

Verificatio n Measure ment

1 Heat Size Order /Spe cificatio n

Drawing Drawing

Drg.Spec. Detail Drg.

Lab Report I. R.

2 2

1 3 1 3

3 .

FABRI CATED ITEMS

Fit up Welding Quality NDT Dimensions

MA MI CR MA

Visual Visual Dimensio n UT, RT, MPT LDP Visual Measure ment

100% 100% Order / Spe cificatio n 100%

Drg. Spec. Drg. Spec. Drg. Spec. Drg. Spec.

Drg.Spec. Drg.Spec. Drg.Spec. Detail Drg.

I. R. I. R. UT Report I.R.

2 2 2 2

1 3 1 3 1 3 1 3

4 .

PAINTING

Paint Thickness

MA MI

Visual Film Thickness

100% Sample

Drg. Spec. Drg. / Specificati on.

Drg.Spec. Drg.Spec.

Painting Certifica te Painting Certifica te

2 2

1 1 3

Quality StandardsBasic StandardsSpecifying general requirements with basic significance eg.Quality Management Systems, drawings & tolerances ISO 9000 ff, EN 4500 ff, ISO 17000 series

Special Basic StandardsSpecifying matters for several applications eg. Test procedures, welding requirements, materials ISO 3834

Special StandardsProduct or application standards eg. Pressure vessels, piping, railway cars ISO 16528, EN 1090, ISO/DIS 10721, EN 15085,

Quality Management in WeldingBasic Standard for QMSISO 9001 -2000

ManufacturingISO 3834, EN 1011, ISO 5817

PersonnelISO 9606, EN 287, ISO 14731, ISO 14732

ProceduresISO 15607 15614

Testing and Inspection PersonnelISO 9712, EN 1289

Materials and Calculation & Design

Application of ISO 3834Certification of companies in accordance with ISO 3834 Parts 2, 3 or 4 Certification of personnel in accordance with ISO 14731

ISO 14731 Requirements for Welding Co-ordination PersonnelWelding Co-ordination : - Manufacturing operations for all welding and welding related activities - The sole responsibility of the manufacturer - May be sub-contracted - May be carried out by more than one person Welding Co-ordinator - Responsible and competent person - Specified tasks and responsibilities - Qualified for each task Welding Inspection - Is part of welding co-ordination

What is ISO 3834?

It is an international standard created by welding professionals ISO 9001 provides the requirements for a quality management system; it does not establish requirements for products. ISO 3834 on the other hand, does provide the quality requirements for a welded product

It encourages a proactive process orientated approach to managing and controlling welding product quality in a workshop or on site It is also a Factory Control System to control activities for the manufacture of the product

2. Why adopt ISO 3834 when we have ISO 9001?

ISO 9001 is a comprehensive standard that lays down quality management system requirements for any organisation ISO 9001 however, does not prescribe specific details for special processes. Welding is regarded as a special process. ISO 3834 was developed to identify all factors that could affect the quality of welded product and which need to be controlled at all stages, before, during and after welding.

3. What are the benefits of specifying the ISO 3834 Standard for the purchaser & specifier

More assurance of contract delivery dates Greater assurance of the quality of welded products Greater reliability and performance of plant Reduction in maintenance costs Reduction or elimination of third party inspection costs More competent suppliers of welded products

4. What are the benefits of using theISO 3834 Standard for the manufacturer? Less rework Jobs completed on time Local and international recognition as a competent organisation Meet the welding-related requirements of ISO 9001 More efficient coordination of welding activities More pro-active and responsible workforce Increased opportunities and capability to bid on jobs Cost savings more efficient technology Reduced surveillance audits and inspections by purchasers with significant savings

5. What are the benefits of using the ISO 3834 Standard for the individual employees?

Helps to do the job more satisfactorily Greater job security Higher regard by other people Professional recognition Satisfied employer and customer More rewarding job position Develops team spirit

6. How important are welding personnel?A key feature of ISO 3834 is the requirement to ensure that people with welding responsibilities are competent to discharge those responsibilities This is achieved by incorporation of another standard, namely, ISO 14731 Welding coordination Tasks and responsibilities The specifying of minium requirements for personnel dealing with welding coordination and welding inspection personnel

7. What is the definition of a manufacturer?

ISO 3834 defines a manufacturer as a person or organization responsible for the welding production. The Standard uses this term to describe any such organisation, including manufacturing organisations supplying welding services, either for new products or for repair and maintenance, as well as other organisations where the application of the requirements of ISO 3834 are relevant A manufacturer may be involved in manufacture, fabrication, construction, repair or maintenance.

8. What are the types of manufacturing organisation that ISO 3834 can be applied to?

Fabrication companies Construction companies - on-site work Repair and maintenance contractors Manufacturers of products Welding workshops on sites under the same technical and quality management Owners of plant with their own workshop(s)

9. What are the types of other organisation that ISO 3834 can be applied to?Those which, though not creating welded product themselves, are specifying or requiring such work from others and are thus involved in weld design, contract development, and review of technical requirements and competencies of subcontractors namely Asset owners without own workshops, both private and government Project management companies Design companies Consultants Government agencies

10. How many parts does ISO 3834 have?ISO 3834: 2005 Quality requirements for fusion welding of metallic materials consists of 6 parts: ISO 3834-1:2005, Criteria for the selection of the appropriate level of quality requirements ISO 3834-2:2005, Comprehensive quality requirements ISO 3834-3:2005, Standard quality requirements ISO 3834-4:2005, Elementary quality requirements ISO 3834-5:2005, Applicable documentation (not full title) ISO/TR 3834-6:2007, Guidelines on implementing ISO 3834

11. How does ISO 3834 link in with ISO 9001? ISO 3834 does not replace ISO 9001 as a quality management system however it contains many attributes that will be important for a welding manufacturer, in both workshops and at field installation sites, seeking ISO 9001 certification Elements of ISO 9001 should be considered when implementing ISO 3834 quality requirements and seeking ISO 3834 certification The specific complementary elements of ISO 9001 are detailed in ISO 3834 WTIA TGN-3834-06 2007 gives more detailed information

12. Describe how the flexibility of ISO 3834 can be applied?ISO 3834 describes the following four situations where ISO 3834 can control welding: Case 1: To provide specific requirements in specifications which require the manufacturer to have a quality management system in accordance with ISO 9001:2000 Case 2: To provide specific requirements in specifications which require the manufacturer to have a quality management system other than ISO 9001:2000 Case 3: To provide specific guidance for a manufacturer developing a quality management system for fusion welding. Case 4: To provide detailed requirements for specifications, regulations or product standards that require control of Fusion welding activites

13. What are the implications to satisfy Case 1: To provide specific requirements in specifications which require the manufacturer to have a quality management system in accordance with ISO 9001:2000

For the purchaser - it implies that they want the manufacturer to have a quality management system in accordance with ISO 9001 and want to ensure that the supplier manages the quality of the product. To achieve this the purchaser must detail the requirements contained in ISO 3834 into the welding specification. For the Manufacturer - it implies that their quality management system must comply with ISO 9001 and that they need to meetthe requirements of ISO 3834. . It is recommended that the supplier incorporates the requirements of ISO 3834 into their ISO 9001 quality management system using it as a bolt on

14. What are the implications to satisfy satisfy Case 2: To provide specific requirements in specifications which require the manufacturer to have a quality management system other than ISO 9001:2000

For the purchaser - it implies that they want the manufacturer to have a quality management system but not necessarily in accordance with ISO 9001. Additionally the purchaser wants to ensure that the manufacturer manages the quality of the product. To achieve this the purchaser must detail the requirements contained in ISO 3834 into the welding specification or contract documents. For the Manufacturer - it implies that they must have a quality management system and meet the requirements of ISO 3834. It is recommended that the manufacturer adopts ISO 3834 and incorporate some elements from ISO 9001 to satisfy this requirement

15. What are the implications to satisfy Case 3: To provide specific guidance for a manufacturer developing a quality management system for fusion welding.

For the purchaser - it implies increased confidence in their supplier for its recognition of the importance of controlling the quality of the welded product

For the Manufacturer - it implies that they recognise the importance of managing the quality of the product that they produce. To achieve this they need to use ISO 3834 as a set of guidelines to identify the key areas that need to be controlled. In addition it lists the elements of ISO 9001 that need to be considered when developing a quality management system

16. What are the implications to satisfy Case 4: To provide detailed requirements for specifications, regulations or product standards that require control of fusion welding activities

For the purchaser and the Manufacturer - it implies that there is an industry-wide recognition of the benefits that ISO 3834 has on the quality of welded products. This ISO 3834 Standard will be specified in specifications, regulations and product standards across all industry sectors such as pressure equipment, mining, building and construction, pipelines, railway etc. Therefore why not take Advantage of these benefits now.

17. What are the main welding requirements covered in ISO 3834 ? Review of requirements Technical review Subcontracting Welding personnel Welders and welding operators, Welding coordination personnel Inspection & testing personnel Welding Inspection personnel; Non-destructive testing personnel Equipment Production and testing equipment; Description of equipment; Suitability of equipment; New equipment; Equipment maintenance

Welding and related activities Production planning; Welding procedure specifications (WPS); Qualification of the welding procedures; Work instructions; Procedures for preparation and control of documents Welding Consumables Batch testing; Storage and handling Storage of parent materials Post-weld heat treatment

Inspection and testing Inspection & testing before welding; Inspection & testing during welding; Inspection & testing after welding; Inspection & test status Non-conformance and corrective actions Calibration and validation of measuring, inspection and testing equipment Identification & traceability Quality records

Quality requirements as per ISO 3834

Selection of Welding Quality Requirement as per ISO:3834Contract Welding Requirement Quality Requirement

When quality system conforming to ISO 9001 is required

When quality system conforming to ISO 9001 is not required

Comprehensive quality requirement

Use ISO 3834-2

Use ISO 3834-2

Standard quality requirement

Use ISO 3834-2

Use ISO 3834-3

Elementary quality requirement

Use ISO 3834-2

Use ISO 3834-4

Comparison of Welding quality requirements with regard to ISO 3834-2, 3834-3 And 3834-4ElementsContract review Design review Subcontractor Welders, Operators Welding coordination Inspection personnel Production equipment Equipment maintenance

ISO 3834-2Full documented review

ISO 3834-3Less extensive review

ISO 3834-4Establish that capability and information is available

Design for welding to be confirmed Treat like a main fabricator Shall comply with all requirement

Approved in accordance with ISO 9606 Welding coordination personnel with appropriate technical knowledge Sufficient and competent personnel to be available Required to prepare, cut, weld, transport, lift, together with safety equipment and protective clothes Shall be carry out, maintenance plan necessary Necessary No specific requirements, shall be adequate Not required but personal responsibility of manufacturer Sufficient and competent third parties access are needed No specific requirement No requirement

Production plan Welding procedure specification (WPS) Welding procedure approval

Restricted plan necessary

No requirement No requirement No specific requirement

Instruction to made available to welder In accordance with the appropriate part of ISO 9956,approved as application standard or contract demands

Comparison of Welding quality requirements with regards to ISO 3834-2, 3834-3 And 3834-4ElementsWork instructions Documentation Batch testing of consumables Storage and handling of welding consumables Storage of parent materials Post-weld heat treatment

ISO 3834-2

ISO 3834-3

ISO 3834-4No requirement No requirement No requirement

Welding procedure specification (WPS) or dedicated work instructions to be available Necessary Necessary Not specified Not specified

According to suppliers recommended minimum Protection required from influences by the environment, identifications to be maintained Specification and complete record necessary Confirmation to specification necessary No requirement No requirement

Inspection before, during and after welding Non-conformances Calibration Identification Traceability Quality records

As required for specified operations

Responsibilities as specified in contract

Procedures shall be available Procedures shall be available Required when appropriate Required when necessary Not specified Not specified Not specified As required by contract

Shall be available to meet the rules for product liability

Retained for 5 years minimum

Inspection of WeldsDefinition of Inspection as per ISO Std. Inspection is that quality control action by means of examination, observation or measurement to determine the conformance of material parts, components, system,structures as well as processes and procedures with predetermined quality requirements.

Nine Essential Variables of Welding1) Joints 2) Base metal 3) Filler metal 4) Position 5) Pre-heat 6) PWHT 7) Shielding Gas 8) Electrical Characteristics 9) Technique

Inspection Before Welding1) Application Standard 2) WPS,PQR,WPQ 3) Drawings 4) Material Composition 5) Condition of Material 6) Type of edge preparation,method & finish 7) Consumables 8) Welding process 9) Clearance dimensions,Type of backing(if any) 10) Alignment, Tack welds,Presets etc. 11) Pre-heat (if any)

WPS,PQR and WPQWPSWelding Procedure Specification is a written document to provide direction for making production weld to the code requirement. Procedure Qualification Record is a record of the welding data used to weld a test coupon. It is also contains the test results of the test specimen. Welding Performance Record determines the ability of the welder/welding operator to achieve the minimum requirement specified for an acceptable weldment.

PQR

WPQ

ASME CodeASME code widely used in India WPS Format - QW 482 PQR Format - QW 483 WPQ Format QW 484

WPS Format as per ASME Section IX

QW-482 Front side

Inspection During Welding1) Welding Process Parameter 2) Inter pass Temperature 3) Filler metal/Electrode condition 4) Inter pass cleaning 5) Distortion 6) Flux /Shielding gas flow

Inspection After Welding1) Dimensional accuracy 2) Appearance of the weld 3) Post Weld Heat Treatment (if any) 4) Evaluation of internal and surface defects with or without the aid of Destructive/Nondestructive testing.

Comparison Between ASME Sec. IX and ISO 9606- ScopeAs per ASME Sec. IX The rules in this section apply to the preparation of WPS, PQR and qualification of welders and welding operators for all types of manual and machine welding permitted in this section. As per ISO 9606-1:1994 This part of ISO 9606 specifies requirements, ranges of approval, test conditions, acceptance requirements and certification for approval testing of welder performance for the welding of steels.

Comparison Between ASME Sec. IX and ISO 9606- ReferenceAs per ASME Sec. IX ASME Sec.VIII and ASME B 31 As per ISO 9606-1:1994 ISO 857,1106-1,1106-2, 1106-3, 2560, 3452, 3580, 3581, 4063, 5173, 5817, 6520,6949, 9956-2 and 9956-3

Comparison Between ASME Sec. IX and ISO 9606- DefinitionAs per ASME Sec. IX As per QW- 492 As per ISO 9606-1:1994 1) Welder a) Manual & b) Welding operator 2) Examiner Or Test Body 3) WPS 4) Range of Approval 5) Test Piece 6) Test Specimen 7) Test

Comparison Between ASME Sec. IX and ISO 9606- VariablesAs per ASME Sec. IX Joints ( QW-402) Base Metal ( QW-403) Filler Metal ( QW-404) Position ( QW-405) Preheat (QW-406) Postweld Heat Treatment (QW407) Gas ( QW-408) Electrical Characteristics ( QW409) Technique (QW-410) Note- Varies with different welding processes As per ISO 9606-1:1994 Welding Processes Joint Type Material Group Filler metal, Shielded gas and flux Dimensions Welding position

Comparison Between ASME Sec. IX and ISO 9606- Material GroupingAs per ASME Sec. IX Steel & Steel alloys Aluminium & Al. base alloys Copper & Cu. base alloys Nickel & Ni. base alloys Titanium & Ti. base alloys Zirconium & Zr. base alloys As per ISO 9606-1:1994 Low-carbon unalloyed steels and/or low alloyed steels (W01) Cr-Mo and/or Cr Mo V creep resistant steels (W02) Fine grained structural steels normalised,quenched and tempered as well as thermomechanically treated steels and nickel steel with Ni content 2% to 5% Ferritic or martensitic stainless steels with Cr content 12% to 20%. Stainless ferritic-austenitic and stainless Cr-Ni steels.

Comparison Between ASME Sec. IX and ISO 9606- Position-Plate-ButtAs per ASME Sec IX

As per ISO 9606

Comparison Between ASME Sec. IX and ISO 9606- Position-Plate-FilletAs per ASME Sec IX

As per ISO 9606

Comparison Between ASME Sec. IX and ISO 9606- Position-Pipe-FilletAs per ASME Sec IX

As per ISO 9606

Comparison Between ASME Sec. IX and ISO 9606- Position-Pipe-ButtAs per ASME Sec IX

As per ISO 9606

Comparison Between ASME Sec. IX and ISO 9606- Type of TestAs per ASME Sec. IX A) For Butt Weld i) Transverse side bend, ii) Transverse Face Bend iii) Transverse Root Bend B) For Fillet Weld i) Fracture Test ii) Macro Examination C) Visual D) Radiographic Examination As per ISO 9606-1:1994 Visual Radiography Bend Fracture MPI or LPT Macro (Without Polishing)

Comparison Between ASME Sec. IX and ISO 9606Expiry or Renewal of QualificationAs per ASME Sec. IX When the welder has not welded with a process during a period of 6 months or more, his qualifications for that process shall expire; unless, within the six months period to his expiration of qualification a) A welder has welded using a manual or semiautomatic welding which will maintain his qualification for manual and semiautomatic welding with that process. b) A welding operator has welded using a machine or automatic welding which will maintain his qualification for machine and automatic welding with that process. There shall be no specific reason to question the welders skill and knowledge As per ISO 9606-1:1994 A welders approval shall remain valid for a period of 2 years providing that the relevant certificate is signed at sixmonths intervals by employer/coordinator and that all following conditions at fulfilled a) The welder shall be engaged with reasonable continuity on welding work within the current range of approval. An interruption for a period no longer than 6 months is permitted. b) The welders work shall be in accordance with the technical conditions under which the approval test is carried out. There shall be no specific reason to question the welders skill and knowledge

Weld QualityDiscontinuityAn interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect but all defects are discontinuities.

DefectA defect is a rejectable discontinuity, which occurs in an amount great enough to render a particular object or structure unsuitable for its intended service based on criteria in the applicable code.

Classification of DefectsPlanar defects / Two dimensional defects -E.g. cracks, lack of fusion, lack of penetration, are crtical in nature and are not tolerated to any extent. Voluminar defects / Three dimensional defects -E.g. slag inclusion, cavities, porosities, etc are tolerated to a certain extent depending on the product class and applicable code. Geometric defects-- E.g. excess reinforcement, underfill, root suckback, distortion are also permitted to a certain extent.

Misalignment (hi-lo)Definition: Amount a joint is out of alignment at the root

Cause: Carelessness. Also due to joining different thicknesses (transition thickness) Prevention: Good Workmanship. Repair: Grinding. Careful on surface finish and direction of grind marks.

Undercut Definition: A groove cut at the toe of the weld and left unfilled. Cause: High amperage, electrode angle, long arc length, rust. Prevention: Set machine on scrap metal. Clean metal before welding. Repair: Weld with smaller electrode, sometimes must be low hydrogen with preheat. Sometimes must gouge first.

Undercut

Insufficient Fill on the Root Side (Suck back) Definition: The weld surface is below the adjacent surfaces of the base metal at the weld root. Cause: Typically improper joint preparation or excessive weld pool heat. Repair: Back weld to fill. May require removal of weld section by grinding for access to the joint root.

Suck back

Excessive Concavity or ConvexityDefinition: Concavity or convexity of a fillet weld which exceeds the specified allowable limits

Cause: Amperage and travel speed Prevention: Observe proper parameters and techniques. Repair: Grind off or weld on. Must blend smoothly into the base metal.

Concavity

Convexity

ReinforcementThe amount of a groove weld which extends beyond the surface of the plate Face ReinforcementExcessive Insufficient Improper contour

Root Reinforcement

Excessive ReinforcementDefinition: Specifically defined by the standard. Typically, Reinforcement should be flush to 1/16(pipe) or flush to 1/8 (plate or structural shapes). Cause: Travel speed too slow, amperage too low Prevention: Set amperage and travel speed on scrap plate. Repair: Remove excessive reinforcement and feather the weld toes to a smooth transition to the base plate.

Excessive reinforcement

Insufficient Reinforcement Definition: Specifically defined by the standard. Typically, Underfill may be up to 5% of metal thickness, not to exceed 1/32 as long as the thickness is made up in the opposite reinforcement. Not applied to fillet welds. Cause: On root reinforcement - Too little filler metal will cause thinning of the filler metal. In OH position, too hot or too wide will cause drooping of the open root puddle. Prevention: Use proper welding technique. Use backing or consumable inserts. Use back weld or backing. Repair: Possibly simply increase the face reinforcement. If back welding is not possible, must remove and reweld.

Insufficient reinforcement

Burn-through Definition: When an undesirable open hole has been completely melted through the base metal. The hole may or may not be left open. Cause: Excessive heat input.

Prevention: Reduce heat input by increasing travel speed, use of a heat sink, or by reducing welding parameters. Repair: Will be defined by standards. Filling may suffice. Otherwise, removal and re welding may be required.

Burn-through

Lack Of Penetration Definition: When the weld metal does not extend to the required depth into the joint root Cause: Low amperage, low preheat, tight root opening, fast travel speed, short arc length. Prevention: Correct the contributing factor(s). Repair: Back gouge and back weld or remove and reweld.

Lack Of Penetration

Incomplete Fusion Definition: Where weld metal does not form a cohesive bond with the base metal. Cause: Low amperage, steep electrode angles, fast travel speed, short arc gap, lack of preheat, electrode too small, unclean base metal. Prevention: Eliminate the potential causes.

Repair: remove and reweld, being careful to completely remove the defective area. This is sometimes extremely difficult to find.

Incomplete Fusion

Arc Strike Definition: Arc strikes result when the arc is initiated on the base metal surface away from the weld joint either intentionally or accidentally Cause: Carelessness of welder Prevention: In difficult areas, adjacent areas can be protected using fire blankets. Repair: Where applicable, arc strikes must be grinded smooth and tested for cracks. If found, they must be remove and repaired using a qualified repair procedure and inspected as any other weld.

Slag Inclusion Definition: Slag entrapped within the weld

Cause: Low amperage, improper technique, Trying to weld in an area that is too tight. Improper wire brushing / cleaning between passes. Prevention: Increase amperage or preheat, grind out tight areas to gain access to bottom of joint. Repair: Remove by grinding. Reweld.

Slag inclusion

Tungsten Inclusion Definition: A tungsten particle embedded in a weld. (Typically GTAW only) Cause: Tungsten electrode too small, amperage too high, electrode dipped into the weld pool or touched with the fill rod. Prevention: Thoriated or Zirconiated tungsten electrodes are used in place of pure tungsten electrodes. Repair: Grind out and reweld

Tungsten inclusion

Spatter Definition: Small particles of weld metal expelled from the welding operation which adhere to the base metal surface. Cause: Long arc length, severe electrode angles, high amperages. Prevention: Correct the cause. Repair: Remove by grinding or sanding.

Spatter

CracksLongitudinal Transverse Crater Throat Toe Root Under bead and Heat-affected zone Hot Cold or delayed

Cracks

Cracks

LaminationsBase Metal Discontinuity May require repair prior to welding Formed during the milling process

Porosity - TypesPorosity is gas pores found in the solidified weld bead. Single Pore Uniformly Scattered Cluster Linear

Porosity

Clustered Porosity

TestingIt is defined as the physical performance of operations to determine quantitative measure of certain properties of a process It aim to determine quantity i.e. to discover facts regardless of the implication of the result.

Types of Destructive & Nondestructive TestingDestructive Tensile Test Macro Test Charpy Test Fracture Test Bend Test Non-destructive Ultrasonic Test (UT) Magnetic Particle Test (MPT) Liquid Penetrant Test (LPT) Radiography Test (RT) Visual Test (VT)

Defects and their Limits as per ISO 5817 -2003

Defects and their Limits as per ISO 5817 -2003 contd.

Defects and their Limits as per ISO 5817 -2003 contd.

Defects and their Limits as per ISO 5817 -2003 contd.

Defects and their Limits as per ISO 5817 -2003 contd.

Defects and their Limits as per ISO 5817 -2003 contd.

Surface Cracks- Detectable by VT

Surface Irregularities-Detectable by VT

Contour Defects- Detectable by VT

Root Defects- Detectable by VT

Visual Inspection Acceptance Criteria as per AWS D 1.1Discontinuity Category &Inspection Criteria Static Loaded (Nontubular) Dynamic Loaded (Nontubular) All Loads (Tubular)

Underrun-In fillet weld upto 1.6 mm subject to it does not exceed 10% of the weld length. No underun is permitted for web-to-flange welds of girder Undercut-Upto 1 in. not to exceed 1mm. For an accumulated length of 2inch in any 12 inch for material above 1in. Undercut above 1.6mm not allowed. Porosity-No porosity in the butt weld traverse to tensile strength. In other butt welds and for fillet weld the size of 1mmin linear inch of weld and shall not exceed 19 mm in 12 in length of weld Porosity-In fillet weld the frequency of porosity shall not exceed one in 100mm of weld length and the maximum diameter shall not to exceed 2mm.

Applicable

Applicable

Applicable

Applicable

Not-Applicable

Not-Applicable

Applicable

Not-Applicable

Not-Applicable

Not-Applicable

Applicable

Applicable

Visual Inspection Acceptance CriteriaDiscontinuity Category &Inspection Criteria Static Loaded (Nontubular) Dynamic Loaded (Nontubular) All Loads (Tubular)

Crack- The weld shall have no crack

Applicable

Applicable

Applicable

Weld/Base-Metal Fusion-Through fusion shall exist between weld metal to weld metal and base metal Crater- All crater shall be filled up to the full cross section except for the ends of the intermittent fillet welds outside the effective length Weld Profiles-Weld profiles shall be in conformance to 5.24

Applicable

Applicable

Applicable

Applicable

Applicable

Applicable

Applicable

Applicable

Applicable

Time of Inspection- Immediately after the completed weld reaches the ambient temp.For ASTM A514,A517,A709 not less than 48 Hrs.

Applicable

Applicable

Applicable

Visual Inspection Acceptance Limit-Piping

As per BS 5289

AcknowledgementsWe gratefully acknowledge the contributions of the following faculty members for developing this module Mr.A.K.Bose Mr.N.Sadasivan R.Banerjee

Thank You