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Is there a welding code for structural welding of aluminum?
Q - I have a welding shop that manufactures small to medium-sized welded structures. I have been acquiring some larger contracts lately in both steel and aluminum structures. Some of my larger steel customers have requested that we have welding procedures and qualified welders for some of the structural steel work. We have used AWS D1.1 Structural Welding Code – Steel, to qualify our procedures and welders for steel.
I am currently trying to increase the amount of aluminum fabrication business and think that I should consider the possibility of producing welding procedures and qualifying my welders for aluminum. Is there a welding code like AWS D1.1 that can be used for aluminum? If so can I transfer my D1.1 procedures and performance qualifications from steel to aluminum?
First, before I answer your questions, I would like to say that I think you are extremely sensible to have considered welding procedures and welder performance qualifications for the various types of welding work in which you are engaged. In general terms, working with a welding code or standard designed for any material, in my opinion, has merit.
I have to believe that the use of welding codes and standards are an opportunity for the welding fabricator to control quality and improve the reliability of their product. If we consider the move by more manufacturing organizations toward the implementation of quality management systems, such as ISO 9000, and the requirement of such systems for process control, we must consider welding as a special process and, consequently, its formal control. Welding codes and standards can be used by the welding fabricator to assist with the development of their process control system. If we examine the major elements of process control, as specified by such standards for quality systems, we will recognize those same elements as being addressed within most welding codes or standards. The first requirement for process control is to have documented procedures defining the manner of production. For welding aluminum, this is the welding procedure specification (WPS). The second requirement is criteria for workmanship, which shall be stipulated in the clearest practical manner. For welding aluminum, this may be the code or standard quality acceptance criteria.
The third requirement is qualification of personnel. For welding aluminum, this is addressed by the code or standard welder performance qualification test. In adopting a welding code or standard, we can acquire these three main elements of a welding control system, along with the reassurance that our fabricated product has been manufactured in accordance with a nationally recognized standard, which may be invaluable if we should ever have to defend the integrity of our welded product.
The welding code for aluminum structures is AWS D1.2 Structural Welding Code – Aluminum. In many ways this code is similar to the AWS D1.1 document. However, the similarity of D1.2 to D1.1 is only in format, which has been chosen to match D1.1 for its simplicity of use, particularly for personnel who employ both of these codes in practice. Because of the totally different characteristics of steel and aluminum relating to their metallurgical structure and related reactions during welding, method of welding, design criteria, and inspection and testing requirements, these two codes are completely independent.
Some background on the aluminum code, AWS has been developing codes for the welding of various steel structures since 1928. In the early 1970s, the need for developing a code for the structural welding of aluminum was recognized. Because of the interest of both The Aluminum Association and AWS, it was decided to begin in the mid-70s, the task of developing a structural welding code for aluminum. Initially, a task force from The Aluminum Association undertook the effort. In 1979, this task force became a subcommittee of the AWS Structural Welding Committee, and the D1.2 Structural Welding Code – Aluminum resulted from the continued activity of that subcommittee.
The current edition of AWS D1.2 is the 1997 edition. This 212 page document is divided into 10 sections and contains annexes A through J and also a comprehensive commentary prepared to generate better understanding in the application of the code to welding in aluminum construction. Sections 1 through 6 and 10 constitute a body of rules for the regulation of welding on aluminum structures.
Section 7, 8, and 9 contain additional rules applicable to specific types of non-tubular and tubular structures and should be used as a supplement to the first six sections. Key features of each of these sections are the list of dimensional tolerances and the weld quality requirements.
These are provided for non-tubular structures under static and dynamic loadings. For tubular structures, two classes of structures are identified. Class I structures are those in the general class of luminaries, traffic signals and overhead sign supports. All other tubular structures are class II. Many of the requirements (dimensional and weld quality) are more stringent for class II structures.
Recommended joint details have been prepared for various complete joint penetration and partial joint penetration groove welded joints. Herein lies one of the major differences between the Structural Welding Code – Steel and the code for aluminum. While the steel code allows for prequalified welding procedures, the code for aluminum does not. This is mainly because of the many and varied possible welding conditions that can be obtained with the semi-automatic welding variables most often used with aluminum, and the wide range of both heat-treatable and nonheat-treatable alloys that may be welded under this code. Therefore, all of the joint details and the welding procedures used with the code shall be individually qualified and included in the Welding Procedure Specification (WPS).
Procedures and standards are outlined in the code for several methods of nondestructive testing. Methods included are visual, radiographic and dye-penetrant. Ultrasonic testing is permitted, but the procedure and acceptance criteria shall be specified in the contract documents.
Unlike the steel structural code, D1.1, the aluminum structural code, D1.2, does not cover design considerations such as the allowable stresses for load-carrying members. This information is covered by reference to the Aluminum Design Manual, published by the Aluminum Association.
A - In direct answer to your questions, yes, there is a welding code like AWS D1.1 that can be used for welding aluminum, (It is AWS D1.2 Structural Welding Code – Aluminum) and no, you cannot transfer your procedures and performance qualifications from steel to aluminum. If you desire to qualify welding procedures and welders for aluminum welding, you will have to start from scratch, so to speak, and perform this qualification totally independent of your current steel qualifications.
Note: At the time of writing the most current edition of AWS D1.2 was the 1997 edition and the 2003 edition was about to be released and is now available.