Author: S. K. Gupta,
B.E., C.E., FIE., FIIW.,
MISNT., MAE., MITD.
Welding Management Part – III is the most important part in Weld Management as it specifies , confirms and recognizes the ability of a manufacturing organization and its welders to fabricate and weld welded structures.
PARTS OF THE ARTICLE (Each part will be published in different WeldFab Tech Times Issues.)
Part – I : Deals with the Framework of Data Based Management system outlined very briefly.
Part – II : Deals with the Materials used in fabrication and related data.
Part – III : Provides details of the Data content to formation of WPS,PQR and WPQ.
Part – IV : Deals with the data on Welding Processes, Equipment and Consumables.
Part – V : Illustrates and explains how the Welding Management Software works .
INTRODUCTION
Welding is used extensively as a major process in fabrication and manufacturing products ranging from Nano components to massive steel structures. Since the inception of shielded arc welding process in 1907, a proliferation of welding processes and related technologies have been developed now covering a wide range of materials, products and applications in practice.
At present, SMAW, GMAW,FCAW, GTAW, SAW, PAW, FSW, EBW , Resistance Welding etc are considered to be the basic processes, based on which specialized branch processes have been developed and effectively applied.
It is imperative to mention here that along with the process, development, manufacture and application of welding equipment and consumables have multiplied astronomically.
In order to keep up the Quality Standards of the Process and products a large number of Destructive, Nondestructive, Analytical and Statistical Process Control Techniques are in regular practice.
International Standards, Codes and Specifications in conjunction of different National Specifications have been formulated on every aspects of Process, Equipment, Consumables, Operators, Operation and Products.
All the above mentioned areas covering Welding have generated vast number of Information in the form of Data and also continuing to generate equal volume of it every period of time. It is not possible for any individual or even any manufacturing organization to store, access, retrieve and apply useful data to the best advantage. But, individually if we can identify our needs, store methodically and systematically welding data used in industries, updating these to the current standards and use Computer Software as the Welding Management System benefits will show all round Production – Operation Management especially where Welding is used as the main Manufacturing Process.
WELDING PROCEDURE – BASIC FACTS
As welding becomes a modern engineering technology, it requires that the various elements involved be identified in a standardized way. This is accomplished by writing a procedure which is simply a “manner of doing” or “the detailed elements (with prescribed values or or range of values ) of a process or method used to produce a specified result .”
The AWS definition for a welding procedure is the “detailed methods and practices including all joint welding procedure involved in the production of a weldment. The joint welding procedure, detailed methods and practices employed in the welding of a particular joint.”
NEED FOR W.P.S., P.Q.R. AND W.P.Q
Welding procedures are required when it is necessary to demonstrate that your company has the ability to produce welds possessing the correct mechanical and metallurgical properties. Once the procedure is approved, it is necessary to demonstrate that all your welders working to it have the required knowledge and skill to put down a clean sound weld. Depending on the type of construction, broad welding procedure specifications are usually drawn.
Terminology
WPS – Weld Procedure Specification:
Qualified instructions on how to complete the weld
PQR – Procedure Qualification Record (ASME) & WPAR –
Weld Procedure Approval Record:
Record of the welding parameters and test results
WPQ -Welders Qualification Test Certificate & Welders Performance Qualification ASME Record of Welder test results and ranges of approval
WPS AS PER ASME
A WPS is process ( SMAW , FCAW etc. ), the electrode type, electrical characteristics, base metal used, preheat and the interpass temperatures, travel speed and position, post weld heat treatment, shielding gas and flow rate, and the type of joint being welded.
WPS is a document that describes how welding is to be carried out in production. They are recommended for all welding positions and many application codes and standards make them mandatory a “Welding Procedure Specification” or “Welding Procedure” as it is commonly called . It contains the combination of variables used to make a certain weld.
European Standards
Unlike ASME Section IX, WPS qualification to BS EN ISO15607 in the EN series is not contained in a single document
- BS EN ISO 15614 Specification and qualification of welding procedures for metallic materials
BS EN 1011. STAGES IN WELDING PROCEDUREAND WELDER APPROVAL CHART
- Welding Procedure Specifications (WPS)
The WPSs are prepared to ensure repeatable acceptability of the weld, when the procedure is implemented by trained and qualified professional welders and tested as per qualification standards. Ranges in approval
Welding Procedure Specifications
Procedure Qualification Records
Welders Performance Qualifications
- Weld Procedures
Range of approval is limited to materials with similar chemical composition and mechanical properties to that used in the PQR. Welding is within a strict range of parameters for the essential variables recorded during the PQR test.
- Welder Qualifications
Range of approval is not as restrictive as Procedure testing with fewer essential variables. One welder performance qualification can cover many WPS’s.
Welding Procedure Qualification Test
The main reason for carrying out a Welding Procedure Qualification Test is to show that following a given set of parameters will produce a welded joint that has the properties that satisfy the design requirements
The advantage of computer-aided WPS is to make sure that essential, supplementary essential, and nonessential variables in Standard Codes like ASME’s Boiler and Pressure Vessel Code Section IX, AWS D1.1, API 1104, or any other code being used are being followed to fulfill the requirements. The Fabricator / Manufacturer should have a standard Format of WPS in which relevant data / information / diagrams are incorporated and preparation will then take minimum time. Also past WPSs must be documented in the computer so that references can be made. It has been observed that ASME Section IX if followed meticulously, acceptance by the Client/ Customer will be easier. Every WPS must bear the Company Logo, Address and other details, Serial Number and a Code to identify Product wise WPS.
Components of a welding procedure
- Parent material
- Type (Grouping)
- Thickness
- Diameter (Pipes)
- Surface condition)
- Welding process
- Type of process (MMA, MAG, TIG, SAW etc)
- Equipment parameters
- Amps, Volts, Travel speed
- Welding Consumables
- Type of consumable/diameter of consumable
- Brand/classification
- Heat treatments/ storage
- Joint design
- Edge preparation
- Root gap, root face
- Jigging and tacking
- Type of baking
- Welding Position
- Location, shop or site
- Welding position e.g. 1G,2G, 3G etc
- Any weather precaution
- Thermal heat treatments
- Preheat, temps
- Post weld heat treatments e.g. stress relieving
Mechanical Properties
- . Ability of a material to withstand deformation under static compressive loading without rupture
- Ductility … Ability of a material undergo plastic deformation under static tensile loading without rupture. Measurable elongation and reduction in cross section area
- Toughness… Ability of a material to withstand bending or the application of shear stresses by impact loading without fracture.
- Hardness Measurement of a materials surface resistance to indentation from another material by static load
- Tensile Strength…Measurement of the maximum force required to fracture a materials bar of unit cross-sectional area in tension
- The amount of deformation which metal can withstand under different modes of force application
Testing
Tests for required properties
- Tensile tests (Transverse Welded Joint, All Weld Metal)
- Toughness testing (Charpy, Izod)
- Hardness tests (Brinell, Rockwell, Vickers)
- Bend testing
- CTOD (Crack Tip Opening Displacement)
- Corrosion tests, HIC & SOHIC Tests
Tests for weld quality
- Macro testing
- Fillet weld fracture testing
- Butt weld nick-break testing
- NDE ( VT,PT,MT,RT,UT)
- Codes & Standards
- Procedure Qualification Records (PQR)
Every WPS is to be qualified by PQR, representing a record of the welding variables and the tests conducted to qualify the WPS. The PQR includes the non-destructive and destructive tests based on acceptance criteria as specified in a particular Code or Standard.
Just like WPS Format and details PQR should have the identical system and Markings to connect the related WPS. It must have the test results with certifying testing agency details and credentials. The data entry Engineer must understand the importance of this document for its intrinsic value.
With the emergence of computer software packages that create and manage the PQR and WPS documents, their capabilities have been extended into an area namely welder continuity and certification management. These advanced applications cover the analysis and storage of the welders, plus the WPQRs, which are the official records of a welder’s ability to perform a weld according to a specific welding procedure specification.
PQR information
- Joint design
- Major code rules
- Shrinkage and distortion information
- Preparation processes needed prior to welding
- Cladding materials
- Structural engineers mechanical properties of weld metal
- Postweld-heat-treatment and residual-stress relief data
- Residual-stress information
- Flaw detection and sizing; NDE criteria
- Welding engineers same as for fabricators
- Underwriters and regulators all of the above
- Codes all of the above
- Manufacturing engineers machinability of base and weld metals
- Productivity
- Deposition rate
- Welding-operator qualification
- Costs of filler metals
- Costs of machining
- Plant safety considerations (e.g., dangerous
- By-products)
- Inspection considerations and standards
- Inspection processes (for selection of the appropriate
- Process for a specific kind of inspection)
- Shelf Life of electrodes
- Suppliers and the location of filler and base metals
- Foreign equivalents for filler and base metals —
- indexed on composition
- Researchers same as for fabricators
- Purchasing personnel
- Estimators
- Welders Performance Qualification (WPQ)
Any welder engaged in welding ferrous, nonferrous metals and alloys must pass the Qualification Tests as specified in the code for a particular product. Such tests involve use of the same welding process to be used in fabrication/welding to a specified Position with Consumables and also following the pre weld and post weld heat treatment procedure. The test pieces will be subjected to non-destructive and destructive testing for qualifying the welder.
WPQs are to be prepared for each welder the organization intends to deploy for the products for which the WPS and PQR have been approved by a Client/Customer. Again a Standard Format is to be used incorporating all the details of the welder and the test details. Just like PQR all the test documentation has to be done thoroughly with cross references.
Every welder qualifying for particular process, engagement details etc. must be listed for any quick reference needed.
With the emergence of computer software packages that create and manage the PQR and WPS documents, their capabilities have been extended into an area namely welder continuity and certification management. These advanced applications cover the analysis and storage of the welders, plus the WPQRs, which are the official records of a welder’s ability to perform a weld according to a specific welding procedure specification.
The main reason for carrying out a Welder Qualification Test is to test the ability of a welder to follow verbal or written instructions and verification that the weld produced meets the required standard.
A list of general parameters observed for such qualifications are listed below
- Scope of work and code by which the work is covered,
- Welding process employed,
- Base metals and applicable specifications,
- Type, classification and composition of filler rod and weldments,
- Type of current and current range,
- Welder qualification requirements,
- Joint design and tolerance,
- Joint preparation and cleaning of surface for welding,
- Joint welding details,
- Position of welding involved at factory or at site,
- Preheat, inter-pass and post heat temperatures,
- Peening,
- Tack welding,
- Heat input Electrode run length,
- Post weld heat treatment,
- Repair of weldments,
- Inspection – quantum and stages – acceptable levels,
- Records – WPS, PQR, Welders Performance Qualification
| APPLICATION | APPLICATION CODE | WELD PROCEDURE APPROVAL | WELDER APPROVAL |
| Pressure Vessels | PD 5500
BS EN 13445 series ASME. B&PV Section III- NB(Nuclear) ASME. B&PV Section VIII |
BS EN ISO 15614
ASME. B&PV Section IX |
BS EN 287
BS EN ISO 9606 ASME> B&PV Section IX |
| Process Pipework | BS 2633
BS 4677 BS 2971
ANSI. ASME. B31.1 ANSI. ASME. B31.3 |
BS EN ISO 15614
BS EN ISO 15614 BS EN ISO 15614-1 (if required) ASME IX ASME IX BS EN ISO 15614-1 (if required) |
AWS BS EN 287
BS EN ISO 9606
ASME. B&PV Section IX
|
| Structural Fabrication | AWS D1.1
AWS D 1.2 AWS D1.6 BS EN 1011 BS 8118 |
AWS D1.1
AWS D1.2 AWS D1.6 BS EN ISO15614-1 BS EN ISO-15614-2 |
AWS D1.1
AWS D 1.2 AWS D1.6 BS EN 287 BS EN ISO 9606 BS 4872 |
| Storage Tanks | BS EN 14015
BS EN 12285
API 620 650 |
BS EN 15614 -1, -2
BS EN 15614 -1, -2 ASME Section IX |
BS EN 287
BS EN ISO 9606-2 BS 4872 ASME Sec. IX |
Organisation, Content and Structure of Section IX of the ASME B & PV Code
- Section IX is structured into 2 Parts: Welding (QW) and Brazing (QB)
- Each part is subdivided into four articles, namely;
- General requirements
- Procedure qualifications
- Performance qualifications
- Welding resp. brazing data
- Additionally
- QW contains one article relating to “Standard Welding Procedure Specifications” (SWPS’s)
- Appendices detail all the mandatory and non-mandatory requirements
Organisation, Content and Structure of Section IX of the ASME B & PV Code
- Section IX is structured into 2 Parts: Welding (QW) and Brazing (QB)
- Each part is subdivided into four articles, namely;
- General requirements
- Procedure qualifications
- Performance qualifications
- Welding resp. brazing data
- Additionally
- QW contains one article relating to “Standard Welding Procedure Specifications” (SWPS’s)
- Appendices detail all the mandatory and non-mandatory requirements
Article II – Welding Procedure Specifications – WPS
- A WPS is a written (qualified) welding procedure prepared to provide direction for the making of production welds
- The completed WPS shall describe all of the essential, nonessential, and, when required, supplementary essential variables
- Variables are defined for each process in QW-250 through QW-280
- Each variable shall be addressed with facts, e.g. yes, no, none or any other meaningful definition – not applicable is not acceptable
- Changes to WPS’s are allowed, however:
- Changes in essential and supplementary essential variables require requalification and (therefore) a new WPS
Changes in nonessential variables can be made without requalification, but do need to be documented and the WPS must be revised
Article II – Procedure Qualification Record – PQR
- A PQR is a record of welding data used to weld a test coupon
- It is a record of actual variables recorded during the welding of the test coupons
- PQR shall document all essential and, when required, all supplementary essential variables for each welding process
- Nonessential variables may be recorded (optional)
- All variables are actual values used during welding of the test coupon
- Changes to a PQR are not permitted as it is a record of what happened during a particular welding test, except for editorial corrections and addenda
- All changes except editorial and those invoked by an Addenda, require re-qualification and recertification of the PQR
Article III – Welding Performance Qualification
- Article lists the welding processes with the essential variables that apply to welder and welding operator performance qualifications
- Welder qualification is limited by essential variables given for each process
- Variables are listed in QW-350 / QW-360 and defined in Article IV
- Welder may be qualified by mechanical tests or by radiography of a test coupon or of his initial production welding
- Manufacturer is responsible for conducting tests to qualify the performance of a welder in accordance with a qualified WP
Article IV – Welding Data QW-400 to QW-416 Variables
This Section covers all aspects concerning of welding processes Joints, base and filler metal, positions, preheat, post weld heat treatment, gas, electrical characteristics and technique
However, do NOT read individual paragraphs on their own but in conjunction with procedure or personnel qualification requirements only
Article IV – Welding Data QW-420 to QW 424 Material groupings
- Base metals are assigned P-Numbers in table QW / QB – 422
- P-Number: Ferrous / Nonferrous material according to base metal spec
- In order to reduce the number of procedure qualifications, each individual P- Number potentially covers a wide variety of materials
QW-430 to QW-433 F – Numbers
- Grouping of electrodes and other welding consumables
- Usability characteristics
- Principal based on grouping similar to P numbers
- Table QW-432 shows F, ASME (SFA….) and AWS
Welding Procedure test
- Part 1:Arc welding of Steels and nickel alloys
- Part 2: Arc welding of aluminium and its alloys
- Part 3: Fusion and pressure welding of non-alloyed and low-alloyed cast irons
- Part 4: Finishing welding of aluminium castings
- Part 5: Arc welding of titanium, zirconium and their alloys
- Part 6: Arc and gas welding of copper and its alloys
- Part 7: Overlay welding
- Part 8: Welding of tubes to tube-plate joints
- Part 9: Underwater hyperbaric wet welding
- Part 10: Hyperbaric dry welding
- Part 11: Electron and laser beam welding
- Part 12: Spot, seam and projection welding
- Part 13: Resistance butt and flash welding
BS EN ISO 15612: 2004: Specification and qualification of welding procedures for metallic materials – Qualification by adoption of a standard welding procedure
- BS EN ISO 15610: 2003 Specification and qualification of welding procedures for metallic materials –
Qualification based on tested welding consumables
- BS EN ISO 15611: 2003: Specification and qualification of welding procedures for metallic materials –
Qualification based on previous welding experience Again , unlike ASME Section IX, Welder qualification in the EN series is not contained in a single document
- BS EN 287-1:2011 Qualification test of welders – fusion welding – Part 1: steels
- BS EN ISO 9606-2: 2004: Qualification test of welders – fusion welding.
- Part 2: Aluminium and Aluminium alloys
- Part 3:Copper and Copper alloys
- Part 4:Nickle and Nickel alloys
- Part 5: Titanium and Titanium alloys
- BS EN 1418 : 1998 Welding personnel – Approval testing of welding operators for fusion welding and resistance weld setters for fully mechanised and automatic welding of metallic materials
Material Grouping As with ASME , materials are grouped together in ISO15608 to reduce the number of procedures required. Steel Groups are:
- Group 1 C-Mn Steels
- Group 2 Fine Grain/TMCP Steels
- Group 3 QT or PH (except stainless steels)
- Group 4 Low Vanadium Cr-Mo Steels
- Group 5 Vanadium Free Cr -Mo Steels
- Group 6 High Vanadium Cr-Mo Steels
- Group 7 Ferritic, Martensitic and PH Stainless
- Group 8 Austenitic Stainless
- Group 9 Ni Alloy Steeল
- Group 10 Duplex Stainless
MATERIALS ( QW / QB 422
All the materials that can be used for pressure vessel manufacture have been grouped under different ‘P’ numbers. The object of grouping the base metals is to reduce the number of qualifications required.
The ‘P’ number grouping of materials is based essentially on comparable metal characteristics such as composition, weldability, and mechanical properties. The grouping does not mean that the base metals may be indiscriminately substituted for a base metal, which was used in the qualification test without consideration of the metallurgical properties, post weld heat treatment, design, mechanical properties and service requirements.
- The ‘P’ number groupings are as follows
- P01 to P11……….. Steel and steel alloys
- P21 to P25……….. Aluminum and aluminum base alloys
- P31 to P35…………Copper and copper base alloys
- P41 to P 47……… Nickel and nickel base alloys
- P51 to P53…………Titanium and titanium base alloys
- P61 to P62…………Zircinium and zirconium base
- P numbers for steel are as follows :
- P1…………………Carbon steel
- P3…………………1/2 Mo steels
- P4…………………1 Cr ½ Mo steels
- P5A………………..2 ¼ Cr 1 Mo steels
- P6…………………13 Cr steels
- P7………………….17 Cr steels
- P8………………….Austenitic Stainless steels
- P9A………………… 2 ½ Ni Steels
- P10A……………….Mn ½ Ni-V steels
- P11…………………9 Ni steels
BS EN ISO 15614-1 Main ranges of qualification Section 8 Range of Qualification:
- 1: General
- 2 Related to manufacturer
- 3: Related to Parent Material
- 4 Common to all Welding Procedures
- 5 Specific to Processes
- Validity is restricted to workshops and sites under the same technical and quality control.
- Parent Material : Tables 3 & 4.
- Thickness: Tables 5 & 6.
- Diameter: Table 7
- Position: All positions (except vertical down) when there are no hardness/ impact test requirements
BS EN 287-1 Qualification test of welders – fusion welding – Part 1: steels Covers:
- Essential variables and range of qualification
- Test piece form and size
- Welding conditions
- NDE/mechanical tests
- Acceptance requirements
- Period of validity and prolongation requirements
- Retest requirements in case of failure
