Welded Steel Pipe Lap Joints—An Evolution

There have been numerous papers involving failures of welded lap joints on steel pipe. The most common lap joint failures referenced include Denver Water's Conduit No. 27 and the City of Atlanta's 72-inch diameter pipeline. There were numerous problems with both pipelines. The authors will list the items that were common in both the Atlanta problem and Denver Water's failures. It is the authors' opinion that not one of the problems led to the failures but a combination of conditions led to the failures. This paper will look at the changes in steel making and how these process changes alleviate some of the problems involved with lap joint pipe. This paper will also go through the steps taken in AWWA Standards to prevent, with proper safeguards, the occurrence of future failures of the type and magnitude of the reported failures. These safeguards include engineering procedures, manufacturing restrictions, and installation STET procedures. Finally the paper will make recommendations on how to write a specification to help prevent failures of this type.