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Technical Memorandum 005-6 - The Utility and Efficacy of Welding Collars
Technical Memorandum 005-6 - The Utility and Efficacy of Welding Collars Imprimir
Lunes, 07 de Noviembre de 2011 17:27




For the majority of projects, the process of well design is a relatively straightforward exercise in which sound engineering principles are combined with the experience of the designer to select specific methods and construction materials to meet or exceed the performance objectives of the client. While there is no denying the obvious importance of performance objectives such as production capacity and efficiency, it is easy to overlook the importance of selecting materials that will facilitate the contractor’s efforts to construct the well. This memorandum explains how the welding collars enable a contractor to more easily complete the well installation in a safe and timely manner.


Types of Connections Steel well casing, louvered well screen and continuous wire-wrapped (CWW) well screen are manufactured in various lengths usually ranging from 10 to 40 feet. These individual joints are assembled at the job site, connected to one another, and lowered into the borehole as a continuous string. The four types of connections most often used in the water well industry are: 1) plain end; 2) threaded and coupled; 3) bell and spigot; and 4) welding collars. Most large diameter wells (i.e., greater than 12 inches in diameter) are constructed with casing and well screen that have plain ends or welding collars; both are described below.

Plain Ends. Casing and screen with plain ends are manufactured with either beveled or square edges depending upon the wall thickness; connections are made by butt welding in the field. Plain ended casing and screen have smooth sides and a uniform outside diameter (O.D.). With a uniform O.D., a tremie pipe and/or other ancillary pipes will lie flat up against the casing and screen minimizing their cross sectional diameter. An added benefit of the uniform O.D. is that gravel is more easily placed and consolidated in the annulus.