WELDING PROCEDURES

There are many factors involved in the preparation of any welded joint. The detailed methods and practices used to prepare a particular weldment are called the welding procedure. A welding procedure identifies all the welding variables pertinent to a particular job or project. Generally, these variables include the welding process, type of base metal, joint design, welding position, type of shielding, preheating and postheating requirements, welding machine setting, and testing requirements.

Welding procedures are used to produce welds that will meet the requirements of commonly used codes. The American Welding Society (AWS) produces the Structural Welding Code that is used for the design and construction of steel structures. Another code that is used for the construction of steam boilers and pressure vessels is published by the American Society of Mechanical Engineers (ASME). These codes provide a standardized guide of proven welding practices and procedures.

While you are not directly responsible for developing welding procedures, you could be assigned to a welding job that requires you to follow them. For example, when a job is assigned to a Naval Construction Force unit, it is accompanied by a set of drawings and specifications. When there is welding required for the job, the specifications normally require it to be accomplished according to a specific code requirement. For instance, if your unit is tasked to fabricate a welded steel structure, the specifications may require that all welding be accomplished according to AWS D1.1 (Structural Welding Code). The unit is then responsible for ensuring that the welders assigned to the job are qualified to produce the welds according to this welding procedure specification. As shown in figure 3-37, a welding procedure specification is simply a document that provides details of the required variables for a specific welding application.

For an NMCB, the welding procedure specification is normally prepared by the certified welding inspector at the local Naval Construction Training Center. Using the Structural Welding Code, along with the project drawings and specifications, the welding inspector develops a welding procedure specification that meets the requirements of the job. The importance of this document is that it assures that each of the variables can be repeated by qualified welders.

Once a welding procedure specification has been developed and qualified, welders are then required to perform a Welding Performance Qualification test. After the test is complete, the weld specimens are tested according to the requirements of the Welding Procedure Specification. You may use either destructive or nondestructive tests. One example of a destructive test is the guided-bend test. An X-ray test is considered nondestructive. Testing is discussed in greater detail later in this training manual.

NOTE: When you are assigned to do a welding job, make a thorough examination of the drawings and specifications. Look carefully at the notes on the drawings and Section 5 (metals) of the specifications. If specific codes are cited, inform the project supervisor so that you can receive the training needed to perform the required welds.

DRAWINGS

Drawings or sketches are used to convey the ideas of an engineer to the skilled craftsman working in the shop. As a welder, you must be able to work from a drawing in order to fabricate metal parts exactly as the engineer has designed them.

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