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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