The Ultimate Skills Challenge — Pipe vs. Plate Welder
Sixteen factors that should be considered to determine a welder’s skill level are reviewed ROY O. CHRISTENSEN is an integrity specialist, Christensen Qualityworks, Inc., Alberta, Canada. Reprinted with permission: The Welding Journal It is a commonly held belief that plate or structural welding is not as difficult as pipe or pressure welding. According to an article titled “The Basics of Welding Certifications and Test Positions,” plate certifications are easiest to pass, and pipe certifications are harder because of ever-changing positions and because there is never a simple straight line (Ref. 1). But is that the case, or is it just a myth?
This article will explain many factors that contribute to welder skill. Metalworking is an ancient craft that uses modern technologies and has become increasingly complex. This article will also provide brief overviews of many welding topics, as well as prove who the best welder really is. For a list of welding abbreviations and explanation of other terms, see the Welding Dictionary (Ref. 2) or do a Google search for other online resources for more information.
Introduction
Welders use welding technology to join, shape, and cut metal parts. They make pressure vessels and pipelines, work joining beams or girders in the construction industry, and manufacture industrial components and consumer goods (Ref. 3). Although all position and nonlinear welds are typically more difficult to make than flat position and linear welds, either position or type may be required with structural or pressure welding. So is the product type — pipe or plate — a single good criterion for determining which welder is better? And how can a pipe welder’s skill be compared to a plate welder’s skill when they have different work anyway? There must be more to it than that.
The well-written article “Contrasting Welding Techniques Used on Pipelines and Refinery Piping: Uphill Versus Downhill” (Ref. 4) describes how pipelines and refinery piping are complementary structures, but the techniques for welding them are completely the opposite. The author identifies six criteria that differentiate welding for pipelines vs. refinery piping (i.e., joints, clamps and tacks, techniques, codes and standards, electrode coatings, and welding speeds). So which of these welds may require a better pipe welder, and how would either of their skills compare to those of a plate welder? And how do they compare to tank welders who use plate to build round containment structures?
Welders work with welding procedure specifications (WPSs) that provide guidelines for production welding according to the code of construction. For example, the ASME Boiler and Pressure Vessel Code (BPVC) Section IX QW-101 states that a properly qualified WPS addressing all essential and nonessential (and if required, supplementary essential) variables shall be used for the control of production welding. Standard WPSs (SWPSs) that are prequalified may also be used.
Welding Procedure Specifications are used for all types of welding, from joining reinforcing bars in a precast concrete bridge to the fabrication of a titanium pressure vessel. There are often additional guidelines for production welding that a welder shall follow as well, such as engineering specifications and standard drawing requirements that are incorporated into the fabrication drawings. Similarly, the codes of construction also require that the welder be qualified. The ASME BPVC Section IX QW-102 states that the basic criterion for a welder’s performance qualification is the welder’s ability to deposit sound weld metal or the welding operator’s ability to operate the welding equipment. But wait a minute — what is the difference between a welder and a welding operator? Are these not the same, and what then about a brazer or a brazer and fusing operator?
Welder Skill Factors
So what factors should be considered for determining a welder’s skill level and how could these be used to determine who would win the ultimate welder skills challenge? This is starting to sound complicated and nobody has even struck an arc yet.
In fact, it is not as simple as welding plate vs. pipe or welder vs. welding operator, and there are many more categories to be considered, as will be discussed (not listed in order of precedence). For many of these categories, an experienced welder can quickly learn new procedures or techniques, but some additional training may be required, and a performance qualification test is needed to ensure there is adequate skill for production welding.
Training
Welder training requirements vary significantly by industry, but more importantly, by jurisdiction. Some jurisdictions identify welding as a regulated trade and require welders to be apprentices or journeymen, while others do not. An apprenticeship is an education and training system that teaches trade knowledge and skills through on-the-job training and formal instruction (Ref. 5). The Red Seal is a recognized standard in Canada for tradespeople to work anywhere in the country without further training or examination (Ref. 6). In Alberta, for example, the Safety Codes Act establishes competency and certification requirements for pressure welders (Grades B and C, and tack) and machine welding operators (Ref. 7). There are also mandatory CWB (or AWS in the United States) certifications for companies involved in structural and other welding operations (Ref. 8). Once these regulatory requirements are met, a welder can then be qualified by his/her employer (for example, with further testing), to work as a tacker (fitter), welder (manual, semiautomatic, or automatic), or welding operator (machine or wire process), for production welding. The welding processes used are very different, however, so the skill sets may not be interchangeable. As a result, a welder would not become qualified for another process without completing additional training.
Experience
If someone says they have 10 years’ experience, it could be 10 years of varied experience or one year’s experience ten times. There is a big difference. Also, today’s workforce is very mobile, so travel may be required for temporary or permanent employment. This means that a welder may have worked in other industries or jurisdictions that have comparatively more or fewer regulations and requirements. This includes domestic and international experience, but no case is a guarantee of any better training or skill for whichever process in particular. A welder’s experience may or may not be documented with various training, regulatory, and performance certifications. Some welders’ skills are not qualified, but these are gained with experience and learned on the job. For example, metals always expand when heated and always contract when cooled. Methods for accommodating and controlling these forces can include misaligning fitup, weld sequencing, and/or flame straightening after welding in order for the final product to meet dimensional tolerances.
Qualifications
Welders must be qualified for the production welding they will perform and may also need to be requalified after a specified period (for example, two years), or if the welding process is not used (for example, six months). Employers, therefore, keep a current log of welders’ identifications and qualifications in order to maintain a qualified workforce for production welding.
Welder qualification may be done with nondestructive examination (NDE), with destructive testing on sample welded coupons, or with NDE on production welds. Welders often hold many certifications or “tickets” for welding with various welding processes, base and filler metals (i.e., electrodes), positions, thicknesses, diameters, and other variables. These qualifications may or may not be transferrable between employers or accepted by others (e.g., clients or end users). Welders may therefore need to perform additional preemployment or job site qualification tests for a new employer or when being assigned to a new project. This ensures that regardless of any qualifications a particular welder may hold, the person’s skill to produce sound welds is proven prior to starting production welding. If at any time the welder’s skill is in doubt, his or her qualifications can be retracted and a requalification test requested. If the test is not successful, retraining may be required prior to another requalification test attempt.
Safety
Welders work with many hazards, including the welding arc and live electrical current, explosive and noxious gases, heat, dust, noise, molten metal, flying sparks, fumes, power tools and machinery, and sharp or heavy objects. As part of their work, welders must always wear personal protective equipment (PPE) and follow safety procedures to protect themselves, their coworkers, and the public.
Code of Construction
Structural and pressure welding have some similarities, but also many differences according to the code of construction. Some welding processes, consumables, and NDE methods are used for both, and the materials can be similar (for example, low-alloy carbon steels are very common, but high alloy and exotic materials may also be used). The differences include design methods, material types, and tolerances or acceptance criteria that all lend themselves to the use of different fabrication techniques. The WPSs and welder’s qualifications tests for structural and pressure welding are also prepared differently, so in spite of any similarities, the differences take precedence.
Learning to weld according to a different code of construction takes time (training), so regardless of a welder’s skill with one, there is no guarantee of performance with any other. For WPS and welder performance qualifications, pressure welding uses ASME BPVC Section IX while structural welding uses CSA W47.1 (AWS D1.1 in the United States).
Products
Welded pressure equipment includes boilers, piping, pipelines, and vessels, while welded structural equipment includes bridges, buildings, cranes, and tanks. Storage and transport tanks may contain product at atmospheric or a higher pressure. There are many other industries that use welding, including transportation (truck and rail cars, passenger and industrial vehicles, motorcycles and bicycles), manufacturing (consumer and industrial goods) and the military. Welding is also used in other applications (auto body or artwork) where requirements are limited (a WPS and welder qualification are not required); however, the weld quality still needs to be fit for purpose with adequate strength and suitable appearance. Welds may or may not be visible in the finished product.
Processes
The most common fusion welding processes are flux cored arc, gas metal arc, gas tungsten arc, metal cored arc, submerged arc, and shielded metal arc welding, which may be manual, semiautomatic, automatic, and/or machine operated. There are, in fact, several dozen welding processes; see the “List of Welding Processes” (Ref. 9) for more information.
With brazing, unlike fusion welding, the base metals are not melted (i.e., only the filler metal is melted), but brazing has useful applications in specific industries (e.g., automotive, refrigeration, and HVAC). It is also one method for joining copper alloys to steel, which cannot be done by fusion welding. Different power sources and equipment are needed for the various welding processes; however, some equipment is designed for use with more than one process.
Consumables
Welding consumables include the use of one or two electrodes (i.e., filler metal, either SMA or wire and consumable or nonconsumable), inserts (with or without and consumable or nonconsumable), shielding and/or purging gas (with or without), fluxes (with or without and cored, coated, or granulated), spatter release, and other products. The consumables used for welding are certified to product standards (for example, AWS and CWB) to ensure quality. Consumable use is specified in the WPS, but there may also be flexibility for production welding and welder preference. The latter is a big factor, because welders prefer working with the process and consumables they have the most experience with and can efficiently produce the best welds.
Joint Design
There are six basic joint types and 15 basic weld types that can be used to create a large number of weldments to suit production welding.
The WPS and fabrication drawing will provide the welder with guidelines to make a weldment, which may be strict or lenient. The root opening (if any), use of backing, and other variables are also specified for partial- or complete-joint-penetration welds. Unfortunately, “weld joints are often designed for welds that cannot be made” (Ref. 10). This is because the designer or welding engineer is not a welder, so something that may look okay “on paper,” is in fact not possible to weld. An experienced welder may be able to offer the designer a compromise to better suit production welding needs and also comply with the WPS. Experienced welders are also able to make production welds without a WPS or fabrication drawing where these are not available or required because of their metalworking knowledge.
Steel and Other Materials
There are hundreds of types of weldable metals, including carbon steel (i.e., low or high alloy), stainless steel, cast iron, nickel, aluminum, titanium, brass, and exotic or other alloys (exotic has different meanings for various users). The materials to be joined are certified to product standards (for example, ASTM and ASME) to ensure quality. When joining two similar base materials, a similar electrode may be used. With dissimilar metal welds (DMWs), the properties for three metals must be considered: the two base metals being joined and the filler metal to join them (Ref. 11). For some DMWs, more than one type of filler metal is required and there may be up to seven heat-affected zones as a result, with different material properties in each zone. Material requirements for welding ranges from pots-and-pans-type work that is relatively straightforward for most welders to critical applications where only very experienced welders working within the strictest parameters can produce satisfactory results.
Techniques
Several topics are discussed in this section as “techniques,” but in a WPS these are identified separately (e.g., positions, pre/postweld heat treatment, electrical characteristics, and welding methods). The electrical current used may be AC or DC (i.e., direct current electrode negative or direct current electrode positive polarity) with up to 1000 A and 40 V or more. Some high-tech welding equipment is computerized so it is smaller and able to produce modified or programmable electrical characteristics. Metals may need preheat, interpass temperature control, and/or postweld heat treatment as a result of welding. The flat welding position is preferred because the welder is working with gravity instead of against it. Higher heat input and larger electrodes can be used in the flat welding position for increased productivity. Positon welding (vertical, horizontal, and overhead) requires different techniques and also sometimes different filler metals. The flat welding position may be done with forehand or backhand techniques, while position welding may be done with uphand or downhand (uphill or downhill) techniques. Welding may be done with string or weave, as single or multipasses, on one or both sides, and with one or more welder per joint or weld. Jigs, clamps, and/or tack welds may be used to hold items in place until welding is completed. A rotating positioner may be used during welding to facilitate increased production, improved quality, and reduced welder fatigue. For this, the electrode is held stationary while the workpiece is rotated. Similarly, for automated welding, the equipment may be placed on a track to produce linear welds. Robotic welding is increasingly being used in many manufacturing facilities. Various techniques may be used for special joining applications (buttering, hot tapping, and temper bead welding) and also to address material effects (thickness and shrinkage). The WPS provides guidelines for production welding, but the welder may determine the actual settings, ranges, and other variables to be used.
Purpose
Welding may be for construction, fabrication, manufacturing, repair work, weld overlay (corrosion or erosion resistance), functional and artistic use, or a combination of these, which all have different requirements for appearance and quality. The materials used and final product often restrict the possible welding methods to be used.
Welders take great pride in their craft and consider workmanship to be of the highest standard if it does not need to be dressed or cleaned up with a grinder after welding. That high standard is not required by most codes of construction, however, which specify tolerances for various conditions or discontinuities ranging from zero to a minimal amount. For architecturally exposed structural steel (AESS) and other applications, the opposite is true. Some welds need to be as flat and smooth as possible, because the finished product will be machined or finished with the weld hidden from view.
NDE
Most codes of construction require that quality control include 100% visual examination of all welds, with a percentage of up to 100% of all welds also subjected to additional NDE. Pressure welds may need to be “x-ray quality,” but structural welds may also have to meet similar high-quality standards for volumetric radiographic testing or ultrasonic testing and/or surface magnetic particle testing, liquid penetrant testing, and visual testing. Nondestructive examination may be required before, during, and/or after completion of the weld. Containment welds for pressure and nonpressure equipment is hydrostatically or pneumatically pressure or leak tested prior to the equipment being placed in service.
Labor Resources
Various groups may claim their welders are the best (union vs. nonunion, employed vs. contracted, and shop vs. rig welders), but of any factor that may affect a welder’s skill, how they are employed or paid is the very least of them.
Workplace
Welders work in a variety of settings ranging from facilities that are very clean to others that by the nature of the work are very dirty. Welders must often travel or get to wherever the work is whether that’s at great height, in a confined space or pipeline ditch, in operating facilities or offshore, and even underwater and outside in any climate and all seasons.
Personal Attributes
Welders must have many personal characteristics (see sidebar below), as well as other attributes. The work requires moving tools, equipment, and workpieces that may be heavy, so they need to be fit. The work may require heavy personal protective equipment for working with molten metal and suitable clothing for working outdoors. Like anyone, however, a welder works best without fighting fatigue, so the equipment is designed to be user-friendly, and the workplace must be as comfortable as possible.
Welders must be creative and good problem solvers to choose the best methods for following the WPS requirements and producing the final product. A welder will become very skilled at certain methods by virtue of the fact that this is what he or she does day in and day out. Welding is a slow process that is measured in inches (or millimeters) per minute, so welders need to be patient. Weld defects, especially with manual and semiautomatic processes, are often the result of the welder working too quickly. With delicate work, the welder’s breathing and heartbeat can impact weld quality. A skilled welder must be able to perform efficient and quality workmanship while dealing with numerous challenges and variables, in addition to the many factors identified in this article.
Something that makes metal, especially steel, more interesting to work with than other materials is the fact that it has many polymorphic forms. There are many types of heat treating processes available for steel (Ref. 13) that are used to provide the required properties in the final product (softness or hardness and corrosion resistance).
Conclusion
Welder training, regulatory, and performance tests and retests are given to ensure that each welder has adequate skill and is able to produce sound welds. Welders are, therefore, constantly being tested for their qualification, even on a daily basis with every weld. What other trade requires such frequent and rigorous testing?
A welder may be very good or even exceptional at the welding they are familiar with and are qualified to perform, but that is not a guarantee their skills are suitable for performing other types of welds, or are better than anyone else’s. Success depends upon the individual’s skills to pass the test at hand and not what other tests he or she may have previously passed and how many tickets may have held. Therefore, a good pressure welder may or may not pass a structural welder’s test and vice versa.
So then, who could the best welder really be? Isn’t comparing plate welders to pipe welders like comparing 4 × 4 monster truck drivers to 18-wheel ice road truck drivers? Yes, they both drive trucks in challenging conditions, although with very different requirements. So, without a doubt, the best welder is anyone who can work safely and efficiently to produce satisfactory welds, and that is the bottom line.
Welders are among the high paying jobs that do not require a degree, and if you are willing to work remotely the salaries can go up exponentially (Ref. 14). Perhaps then the best welder is a happy welder, one who enjoys working with metal and earning more than average.
References
- The basics of welding certifications and test positions. http://www.gowelding.org/, http://metalwebnews.com/howto/welding/welder-certification.pdf.
- Welding Dictionary. Miller Electric Mfg. Co. http://www.millerwelds.com/resources/dictionary.html.
- Welder Apprentice. SAIT Polytechnic. http://www.sait.ca/programs-and-courses/apprenticeships-and-trades/apprenticeships/apprenticeship-welder-apprentice.php.
- Younas Malik, M. Contrasting welding techniques used on pipelines and refinery piping: uphill versus downhill. http://www.pipelineandgasjournal. com/contrasting-welding-techniques-used-pipelines-and-refinery-piping-uphill-versus-downhill?page=show.
- The apprenticeship system of training. SAIT Polytechnic. http://www.sait.ca/programs-and-courses/apprenticeships-and-trades/apprenticeships/additional-information/the-apprentice-system-of-training.php.
- Interprovincial Red Seal. Alberta Innovation and Advanced Education. http://tradesecrets.alberta.ca/experiencedworkers/interprovincial-red-seal/.
- Pressure Welders. ABSA. http://www.absa.ca/ECprogram/Welding/PressureWelders.aspx.
- Mandatory Certification. CWB — Office of Public Safety. http://www.weldquality.org/industry/mandatory-certification.
- List of welding processes. Wikipedia. http://en.wikipedia.org/wiki/List_of_welding_processes.
- Joint design and preparation of metals. My Discount Tools. http://www.mydiscounttools.com/estore/articles/welding/Welding JOINTS.html.
- Avery, R. E. Guidelines for welding dissimilar metals. Avery Consulting Associates, Inc. http://www.nickelinstitute.org/~/Media/Files/TechnicalLiterature/GuidelinesforWeldingDissimilarMetals_14018_.pdf#page=.
- Occupational Profile — Welder, Alberta Learning Information Service. http://occinfo.alis.alberta.ca/occinfopreview/info/browse-occupations/occupation-profile.html?id=71003108.
- Steel. http://en.wikipedia.org/wiki/Steel.
- High-paying jobs that are in demand in Canada right now (with and without a university degree). Workopolis. http://www.Workopolis.com/content/advice/article/high-paying-jobs-that-are-in-demand-in-canada-right-now-with-and-without-a-university-degree/.
