Repair grinding ― An alternative to ultrasonic rejection for oilfield tubes

The price of scrap steel rose from $95 to $140/ton in 1993, making tubular production costs higher and making internal repair grinding of oil field tubes with minor internal surface breaking imperfections an extremely cost effective method for placing potentially reject tubulars back into service. Such imperfections often occur and are presently sized by the shear wave ultrasonic amplitude method. This article is written to illustrate how effective repair grinding can be in producing prime material within the API specifications 5CT, specification for Casing and Tubing; 5D, Specification for Drill Pipe; and 5L, Line Pipe. Ninety percent of high grade and 50--60% of midgrade materials can be saved by this method.