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Sample Metal 3D Printing Process Sample Metal 3D Printing Product
Figure 2 : Modern Metal Fusion Method via 3D Printing Source : www . mida . gov . my / metal-additive-manufacturing /
“ Welding Procedure Specification ” and “ Welder Qualification Test ” respectively . To develop a good quality weld , we need to understand the end use and the best way is through the Engineering Drawings . The technical drawing will most likely spell out the design specifications , allowing one to determine the governing welding code and standard . If not , one may communicate with the Stakeholder or Customer directly to determine the requirement .
In the event the governing welding code is unknown , the fabricator or contractor may propose to the Stakeholder the closest welding code or standard available in the market . With the information , a proposed or preliminary Welding Procedure Specification ( pWPS ) can be developed based on the preferred Welding Process , Base Metal type , Welding Consumable selection , and other key factors . All these factors that will affect the quality outcome of the weldment are classified as “ Essential Variables ”. For instance , the Welding Consumable selected needs to be compatible with the Welding Process and suitable for the Base Metal in terms of both physical and chemical properties to deliver the expected outlook .
With the pWPS finalised , a Welding Procedure Qualification Test ( WPQT ) can be conducted whereby the welding is performed on a “ Test Coupon ” following the pWPS guidelines and predetermined variables . Subsequently , the prepared “ Test Coupon ” might undergo Non- Destructive Testing ( NDT ) before being sent to a recognised laboratory for physical testing ( which may include a chemical test if needed ).
If the laboratory test result does not meet the anticipated outcome , the pWPS needs to be revised and the WPQT repeated till the desired outcome is achieved . Hence , any changes in the variables observed during WPQT will need to be recorded for post-mortem failure root cause study .
● WPQT Test Coupon NDT usually comprises radiographic testing and Magnetic Particular Inspection ( MPI ) / Dye Penetration Inspection ( DPI ) to ensure that no rejected defect exists in the test coupon internal and external respectively .
● Examples of physical tests are the Tensile Test , Bend Test , Charpy Impact Test , Hardness Test , etc .
● Some customers ( particularly in the Oil & Gas Industry ) may request for independent third-party involvement to witness the WPQT and Laboratory Test , including endorsing the PQR and WPS for quality assurance purposes .
All industries rely on proper records to maintain repeatability for a good process system , and the same goes for welding processes . The Procedure Qualification Record ( PQR ) serves this purpose , whereby all variables in the WPQT are transferred to the PQR after passing the laboratory test . The data in the PQR will subsequently be used to develop the Welding Procedure Specification ( WPS ). Basically , WPS makes reference to the PQR but it introduces some flexibility , according to the codes and standards . In other words , the WPS
38 VOL 96 OCTOBER-DECEMBER 2023