By Carlos F Molina
One of the content areas that worked out best for me during my exam three years ago was welding. In the time I presented the exam, the number of questions was different from nowadays. From a total of 16 questions about welding, I got 15 right (nowadays they ask only 8). It helped me a lot knowing about welding.
The body of knowledge gives a broad guide of what will appear in the exam related to welding. It says the following:
The inspector should have the knowledge and skills required to review a Procedure Qualification Record and a Welding Procedure Specification or to answer questions requiring the same level of knowledge and skill. Questions covering the specific rules of Section IX will be limited in complexity and scope to the SMAW and SAW welding processes.
1. Questions will be based on:
a) No more than one process
b) Filler metals limited to one
c) Essential, non-essential, variables only will be covered
d) Number, type, and results of mechanical tests
e) Base metals limited to P1
f) Additional essential variables required by API-650 or API-653
2. The following are specifically excluded:
a) Dissimilar base metal joints
b) Supplemental powdered filler metals and consumable inserts
c) Special weld processes such as corrosion-resistant weld metal overlay, hard-facing overlay, and dissimilar
metal welds with buttering
d) Charpy impact requirements and supplementary essential variables
e) Any PQR and WPS included on the examination will not include heat treatment requirements.
As you can see, some of the questions are based on ASME IX. With this in mind, I decide to put on some articles on successfully reading and reviewing a WPS and a WPQ. Let´s check an introduction.
INTRODUCTION TO ASME IX
ASME IX “Welding, Brazing, and Fusing Qualifications. Qualification Standard for Welding, Brazing, and Fusing Procedures; Welders; Brazers; and Welding, Brazing, and Fusing Operators” is a part of the ASME Boiler and Pressure Vessel Code, that regulates the design and construction of boilers and pressure vessels. API 650 trusts ASME IX for weler procedure and welder performance qualifications
Some important definitions found in QW-200
WPS: A Welding Procedure Specification (WPS) is a formal written document describing welding procedures, which provides direction to the welder or welding operators for making sound and quality production welds as per the code requirements
PQR: The Procedure Qualification Record is a Record containing information about the tests conducted over the welds made to a WPS, the variables used during welding of the test coupon, and the succesfull qualification of that WPS.
WPQ: A Welder Performance Qualification is a document recording the ability of a welder to deposit welds in the manner described in the WPS.
All of the three documents contain a set of variables to control. Variables that may be used in a welding procedure test are divided into 3 categories.
Essential Variables Are variables that have a significant effect on the mechanical properties of a joint. They must not be changed except within the limits specified by this code. e.g. Material thickness range, Material Group, welding proccess, etc. The PQR shall contain all essential variables.
Non-Essential Variables Are variables that have no significant affect on mechanical properties. They can be changed without re qualification of the PQR.
Supplementary Variables Are variables that have an affect on the impact properties of a joint. They are classed as Non-Essential if impact testing is not required. This kind of variables won´t show up in the exam.
All variables listed as essential and non-essential should be addressed on the WPS, while all listed as essential should be addressed in the PQR. Supplementary essential variables should be addressed in both documents when required (See QW-200 of ASME IX). If any of the variables do not apply to the particular application then they should be specified as not applicable. The welding organization can have its own formats for these documents, as long as they meet the aforementioned requirements.
Understanding of the information that should a WPS and a PQR contain is critical. Several WPS can be written on the basis of the successful qualification of the initial preliminary WPS. There is no limit on the number of production WPSs that can be generated from a PQR. And as for the other way around, several PQR can be “summed up” to support a broad WPS, just making sure that the ranges of the variables in the PQRs are the same for the WPS generated.
ASME IX, HOW IT IS ORGANIZED
ASME IX is divided in 4 parts
PART QG, General requirements
PART QW, Welding
PART QB, brazing
PART QF, plastic fusing
We will concentrate in Part QW, which in turn is divided in 5 articles.
• Article I – Welding general requirements
• Article II – Welding procedure qualifications
• Article III – Welding performance qualifications
• Article IV – Welding data
• Article V – Standard welding procedure specifications (SWPS)
In ASME IX, as much as 20 different welding proccesses are mentioned when it has to do with procedure qualification. Essential, non-essential and suplementary variables for welding proccesses can be found in tables QW-252 to QW-269.1 of ASME IX. But remember “Questions covering the specific rules of Section IX will be limited in complexity and scope to the SMAW and SAW welding processes“. Which are the essential variables needed for these 2 proccesses? We can find them in QW-253 and QW-254
The nonmandtory appendix B of ASME IX illustrates the diferent formats for welding procedure specifications, Procedure Qualification records and Welder Performance Qualifications, for the SMAW, SAW, GMAW and GTAW proccesses, and the basis for other welding processes may follow the general format as applicable. You should take a look at them.
In the exam, it is required from the candidate to proficciently review a WPS and its supporting PQR that will be given to him. That´s why it is a good idea to be familiar with the appendix B formats.
SIMPLE FLOWCHART OF A WPS AND ITS SUPPORTING PQR
As we said before, a PQR can be the basis of several WPSs and viceversa. The code only asks for the essential variables to be recorded on a PQR. But just complying with the standard in this case may not be enough to make Welding Procedures of consistent quality. The fact is that a preliminary WPS can be made (although not mandatory), a test set up for this preliminary WPS where all variables should be recorded (essential, non-essential and supplementary), and a PQR containing all of that variables created. After the weld is accepted by testing, now you can stablish a WPS and make it into your procedures. With this recommendations, I created a simple flowchart to understand the proccess.
Well that´s all for now. Next article will have some questions and more info on qualification of procedures and welders.
I have to give a sincere congratulation to the people that recently passed the exam. Two of my readers have passeb by to tell. Congratulations and keep up the good work.