Too often, off-the-shelf welding procedures are used for code compliance and only see the light of day during quality audits. The alternative? Fabricators could optimize the quality and productivity for each application by documenting the desired procedure in a format that can be easily understood by the shop floor welders.
With the intent to govern and guide welding activities, the first step should be to eliminate all of the non-relevant techno-babble and endless array of code-defined variable jargon not used for the application and replace it with suitable tabular data, images and understandable notes. The end result will be less clutter, and therefore, a better chance of the desired procedure being used.
No matter the format, a welding procedure should be the document that provides guidance for welding activities company-wide. By defining the variables to be used for making production welds, fitters can better determine pre-weld preparation and fit-up, welders can perform specified welding consistently and accurately, and inspectors can have an easier time verifying compliance with procedure requirements.
An appropriate analogy is to consider the procedure as a welding recipe with the variables and data serving as the ingredients and the amounts to be used. Like a good recipe that must do more than list ingredients, a good welding procedure must include notes and instructions to accompany the itemized list and data.
Procedure terms and functions
Welding procedures are often used because they are a requirement of the applicable code or standard governing fabrication of the product being produced. They have a variety of names and acronyms, including Welding Procedure Specifications (WPS) in accordance with American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code and Welding Procedure Data Sheets (WPDS) that are required by the Canadian Standards Association (CSA) W59 Structural Steel Welding Standard.
In addition to the WPS and WPDS, other documents are used to document the general welding process. They are used to list the data used when welding a qualification assembly and list the results of required testing, such as tensile testing or chemical analysis.
An example of this type of document is the Procedure Qualification Record (PQR) required to support any WPS for ASME applications. While the PQR does serve an important role, that type of document is not intended for use by shop floor personnel and is not considered a welding procedure.
Quality and productivity
An important function of welding procedures is to help assure the quality of welded products. Procedures are often qualified by welding assemblies and then tested with methods to assure they have the properties to meet application demands. A change in a variable defined as “essential” would require a re-qualification as it may result in a change in weld properties. A change in a variable defined as “non-essential” would not need to be re-qualified, but would need a new welding procedure as it may affect weld soundness.
A change in groove design is an example of this kind of change. If production welds are made within this framework of proven and defined welding procedures, quality welding should result.
While procedures have often been used to control weld quality, another benefit of using documented welding procedures can be seen in productivity gains. Some welding processes can be used within a wide range of operating variables. Without guidance or a procedure to follow, a welder instructed only to use the GMAW process may weld at 200 ipm, 600 ipm or any wire feed speed in between.
This example is extreme, but the three-fold increase in productivity illustrates the possible result of leaving welding parameters up to the discretion of the individual welder. Other items that may have a significant effect on welding productivity include the process used, the electrode diameter used and the joint design used. From a dollars and cents standpoint, all variables affecting the productivity of a welding application should be looked at closely with the optimum parameters defined on a procedure.
Too often, procedures have been documented only for code compliance using canned data from a reference source. Proper welding procedure development should involve experimentation to define optimum parameters, including weld joint design and fit-up as well as process variables specifying specific values or ranges where appropriate.
While there are many good reference resources that can be used as a starting point for defining procedures, an investment in experimentation during procedure development can produce big gains in welding quality and productivity.
But once these optimum procedure variables have been defined, how should they be presented on a procedure document?
Procedures have been documented in many formats, including written paragraphs, tables, sketches and combinations of these items. In some cases, the applicable code, standard or jurisdiction responsible for monitoring compliance have sample welding procedure forms that can be used.
In considering which format or form to use, the primary function of the procedure should be kept in mind: to provide guidance and instructions for personnel in carrying out welding activities. Adding data to an off-the-shelf form sometimes results in a confusing array of data and variables that may include information not relevant to the procedure being used.
Therefore, it’s important for fabricators to understand that welding procedures can be written in virtually any format provided the information needed for code compliance is included. If documents can be presented in a simple and easy-to-read format, their chance of actually being used is increased.
Figure 1 illustrates a sample welding procedure that includes instructions with notes, sketches and tabular data. Items such as electrode classification and diameter should be specified with single values while other values, such as amperage or electrode stickout, should be specified with appropriate ranges or plus/minus tolerances.
In a quality-assured environment specifying single values only invites non-compliance reports. Welding procedures can be developed in any format with considerations, including welding process, level of automation, application requirements, and the skills and literacy of personnel.
Fortunately, today’s software tools have improved the efficiency of welding procedure documentation. Using templates in word processing or forms programs eliminates the need for duplication of common procedure elements.
For example, the first WPS created from a single PQR could be duplicated for other WPSs, changing only the non-essential variable elements, such as welding position or joint design. In custom fabrication shops that use a variety of materials and welding procedures, database software can simplify the process of searching for appropriate procedures to use for new contracts. Some vendors supply dedicated welding management software that can be used to document procedures and provide other benefits, such as logging and flagging welder performance qualification testing requirements.
If 50 welders are only given instructions for making a full penetration groove weld to join 1/2-in.-thick steel plate, many different techniques will probably be used. Which joint preparation, process, electrode, wire feed speed or shielding gas flow rate to use are only some of the selections to be made. If all techniques are evaluated, it may be possible to select the procedure that provides optimum results and have all 50 welders use that procedure.
Assuming a well-developed welding procedure with concise instructions in an easy-to-understand format has been developed, the next consideration is how to ensure these procedures are actually followed on the shop floor. Acceptance and application of procedures can be improved by involving production personnel in procedure development, providing training where necessary and performing routine monitoring.
Qualification and pre-qualification
Another consideration for welding procedure documentation deals with the “pre-qualified” option provided by some codes and standards. CSA W59-03, for example, lists criteria and sketches for partial and full-penetration welds for the SMAW, FCAW, MCAW, GMAW-Sp and SAW processes.
The concept here is that if fabricators document procedures in accordance with the specifications and minimum weld joint preparation dimensions specified in Clause 10, the WPDSs do not have to be qualified by procedure testing as witnessed by the certifying jurisdiction, the Canadian Welding Bureau (CWB). This ensures proven welding procedures are used and saves the time and expense of procedure qualification.
In some cases, however, this investment in procedure qualification can result in significant savings. If for example, a full penetration groove weld procedure is needed for submerged arc welding of 3/4-in.-thick steel onto a backing bar then a 5/8-in. root gap would be needed using a 20° included angle as shown in Figure 2. If it can be proven through experimentation and procedure qualification that a full penetration procedure can be achieved with less root gap or bevel angle, the procedure would then be approved by the CWB.
Senior welding technology students at Conestoga College in Ontario, Canada have a SAW lab assignment where using the S2-1 as a reference, they do procedure experimentation to minimize the joint design and then do a calculation to determine how many feet of weld would be required to pay back a hypothetical $1,500 investment in procedure qualification.
The second illustration in Figure 2 shows a joint design that provided full penetration as proven by metallographic testing and the calculations showing how many feet of weld would be required to pay for the investment in qualification. These calculations, laid out in Figure 3, show that the $1,500 investment in procedure qualification would be paid off after only 24 ft. of welding and that additional welding costs have been lowered by 59 percent.
So while there may be short-term gains from using pre-qualified welding procedures, experimentation to prove alternate procedures and the investment in procedure qualification may provide a recipe for welding cost savings.