1. Use a common sense approach to identify errors. This step is a high-level review and can commonly be done even without a full variable check between the WPS and PQR. For example, are filler metals appropriate for the base materials being welded, are shielding gases or fluxes appropriate for the welding consumables being used, do welding parameters appear to be correct, is the electrical current and polarity correct, is this a material that requires preheat, is the information believable (for example, GMAW process using ER70S-6 with argon gas shielding recorded on both a PQR and WPS), is it accurate, etc. 2. Perform a detailed check. This step is a detailed check of all welding variables required by the code as well as requirements from other applicable standards. Examples of additional requirements include NACE hardness limitations, Charpy toughness, mandatory fabrication code preheat or PWHT, as well as special filler metal requirements. Examples of Common Errors Following are some omissions/errors commonly identified during reviews. For the GMAW process: • Failure to indicate the arc transfer mode (globular, short arc, spray). • Where the transfer mode is indicated, parameters such as amps, volts, and wire feed speed will not produce the indicated arc transfer. Welding Positions: • Failure to indicate uphill or downhill progression on the WPS or PQR. • Interchanging qualification testing terminology on the PQR and WPS, e.g., using 1G, 2G, 3G, 4G, 6G on a WPS instead of F, H, V, OH. Procedure Qualification Tensile Testing: • Failure to perform tensile testing in which the specimen(s) represents the full thickness of the PQR test coupon (reference ASME IX, QW-151.1). 28 Inspection Trends / July 2013 Table 1 — How to Specify Filler Metal Types ASME P-No. 8 Base Metal Type AWS Filler Metal Classification 304 E/ER308 304L E/ER308L 304H E/ER16-8-2 316 E/ER316 316L E/ER316L 316H E/ER16-8-2 Adoption/use of standard AWS WPSs for work under ASME Section IX requirements (ASME IX, Article V): • Failure of the contractor to perform and document a demonstration test required by ASME IX, Article V. 300 Series Stainless Steel: • Failure to utilize a filler metal as corrosion resistant or as creep resistant as the base material. For example, Type 308 is commonly specified for welding Type 316 base materials. While 308 satisfies ASME Section IX qualification requirements, Type 308 fillers in many environments will not be as corrosion resistant as Type 316 base materials. Note that contractor procedures commonly indicate austenitic filler metals such as ER3xx, F-No. 6, A-No. 8 for welding ASME PNo. 8 base materials. For the reviewer, it’s not clear what base material type will be welded nor the specific filler metal AWS Classification that will be used. • While this may be correct from an ASME Section IX perspective, a preferred, unambiguous way to specify the filler is also by AWS classification vs. actual base material type. For example, commonly assigned filler metals on a WPS could be listed as in Table 1. • For welding of stainless steels and high-alloy materials, project specifications typically require purging during welding of single-pass, complete-joint-penetration welds. Welding procedures are commonly submitted, however, without amended requirements for purging. Miscellaneous: • Failure to address mandatory code preheat requirements; e.g. ASME B31.1 mandates minimum preheat for some P-No. base materials. • Utilizing the wrong code edition when specifying PWHT parameters. • For procedures qualified for Charpy impact testing, specifying welding parameters that far exceed the allowable heat input range. Unless a welder has been trained to calculate and control heat input, a heat input limitation stated on the WPS may likely be exceeded during production welding without the appropriate welding parameters listed on the WPS. • Failure to list the applicable code or testing standards on the PQR. AWS D1.1 Qualifications: • Failure to perform or document the required visual examination or radiography examinations on the PQR test coupon. • Failure to identify the specific weld joint details on qualified WPSs. Conclusion While writing and reviewing WPSs and PQRs may seem confusing and to require too many steps at first, keep in mind that many common errors can be found simply by making a checklist, proofreading your work, and using some common sense. SPENCER O. LUKE, P. E., (lukeso@bv.com) is an engineer, Black & Veatch, Overland Park, Kan. He is also an AWS CWI. One of his daily duties is to review welding procedures from companies around the world.
Inspection Trends | Summer 2013
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