EXAMPLE: GTAW & ASME IX
1) whether new PQR has to be performed if there is change in GROVE TYPE from V to U During production OR only revising the WPS by incorporating the changed GROVE TYPE will be enough.
groove design is a nonessential variable, so issue a new WPS and qualify it with the existing pqr
2) Whether gas purging used during GTAW welding can be consider as BACKING.
the flow rate is a nonessential variable, so you may consider it as backing if you are sure for the composition because the composition is an essential variable for some P numbers (see QW-408.9)
3) Please clarify the meaning of paragraph - QW - 403.5( Only for paragraph below point C) with example.
P no may be the same but group no changes in case where the yield point / ultimate tensile strength changes. Then if impact test is required then the WPS must be re-qualified For non ferrous materials there is no group number so you have to use the UNS no.
4) Please clarify the meaning of paragraph - QW - 202.4b(2)with example.
You have a PQR for welding with GTAW for thickness 14 mm. You have an other PQR for welding with SMAW for thickness 20 mm. Now you have to weld a pipe of 40 mm. You can do the root pass or even you can weld 28 mm with GTAW and complete the weld with SMAW. The issue here is that you can use the GTAW although its PQR does not cover 40 mm
5) whether change of electrode clasification under same SFA e.g. change of electrode from E7018 to E7018-1 or VICE VERSA requires qualification of new PQR.
No, F number is the same but if impact test is required then a new PQR is required because the classification is not the same (classification is a supplementary essential variable)
6) Please clarify the meaning of paragraph - QW - 404.12 & 404.33 with example.
Impact test is a requirement: if you change from E7018 to E7018-1 you need to re-qualify. If the filler metal has the G, then if you change from Oerlikon to Thyssen you need to qualify again. The changes of 404.33 do not require re-qualification but you have to write a new WPS to suite production requirements
Dr. G. Dilintas
I&F Regional Technical Manager
Bureau Veritas Piraeus - Greece
Tel: +30 210 40 63 113/4
Fax: +30 210 40 63 118
Introduction The colour formed when stainless steel is heated, either in a furnace application or in the heat affected zone of welds, is dependent on several factors that are related to the oxidation resistance of the steel. The heat tint or temper colour formed is caused by the progressive thickening of the surface oxide layer and so, as temperature is increased, the colours change. Oxidation resistance of stainless steels However, there are several factors that affect the degree of colour change and so there is no a single table of colour and temperature that represents all cases. The colours formed can only be used as an indication of the temperature to which the steel has been heated. Factors affecting the heat tint colours formed Steel composition The chromium content is the most important single factor affecting oxidation resistance. The higher the chromium, the more heat resistant the steel and so the development of the heat tint colou...
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