Within the oil and gas industry, there is a range of specific products and equipment that are unique to the work that is done. In the Texas oil fields, a pup joint is a short piece of drill pipe that is non-standard in length compared to the other pieces of pipe in the string.
Sizing Considerations
The use of pup joints is to easily adjust the length of the drill string with a convenient and pre-fabricated piece of pipe or tube. The most common lengths for a pup joint are typically two feet adjustments from 2, 4, 6, 8, 10, 12-foot lengths. Most commonly a three-foot length is offered as well, at least in the standard option. Perforated joints tend to come in the shorter lengths from two to six feet, although manufacturers can accommodate different size requirements.
In addition, pup joints can come in various diameters. These diameters are designed to match the diameter of pipe and tube. This is measured as the outside diameter and includes the two and three-eighths, two and seven-eighths and three and a half inches. Depending on the manufacturer, there may be heavy or standard wall weights available for these pipes.
The Importance of Quality
While short in length compared to regular piping, it is critical to choose pup joints that are made with quality grades of metal that equal the proprieties of the drill pipe used in the system. This ensures that the pup joint can withstand the same type of stress and pressure, eliminating concerns with a failure of the joint.
Most commonly they are made of J-55, N-80, L-80 and P110 grades of metal. When in doubt, verify the grade of metal of the drilling pipe and choose an equal or better grade for optimal performance.