Casing Crossover and Transition Adapter

What a Crossover Does

A crossover, sometimes called an x-over, is a short machined sub with a different thread at each end. It is used whenever two components in a string cannot be made up directly to each other. Common situations include a tapered casing string where a smaller size is run below a larger one, an existing well where new pipe must tie into an old connection type, and wellhead or hanger interfaces where the casing thread does not match the equipment. Because the crossover is often the component that carries the full string load, its body must be sized for the tensile and pressure rating of the stronger of the two connections, and its material must be compatible with the service environment, including sour service requirements if applicable.

Specifying a Crossover Correctly

A crossover cannot be ordered from a nominal size alone. The complete specification requires, for each end: the outside diameter, weight per foot or wall thickness, thread form and type, and gender, that is whether it is pin or box. In addition, the overall length, the material grade and the drift requirement must be stated. For premium connections, the exact connection name and manufacturer are also required. Where a crossover must meet specific tensile, burst or collapse ratings, the required rating should be stated so the body wall can be sized accordingly. Because most crossovers are made to order, allow additional lead time and confirm the drawing before production begins.