It is very important that a fishing tool man have a good knowledge of different threads used in the Oil Field. They can be categorized as follows: Tool Joint threads, Tubing threads, Casing threads, Line Pipe threads, and Washpipe threads. Many of the casing threads and washpipe threads are the same, like “X-line”.
Each thread has different characteristics and should be studied so they can be recognized by these characteristics. For instance, 4 ½ “ X-hole and 4 ½” I.F. tool joint connections have the same taper per inch and the same number of threads per inch, but the O.D. of the threaded portion of the pin is smaller on the 4 ½” “X-hole”; where as 4 ½” F.H. and 4 ½” A.P.I regular have the same taper and the same number of threads, but they both have more taper and more threads than X-hole or I.F.
With some practice, it is not hard to learn to identify the different tool joint threads if some time is spent learning them. It is also good to know where to find the values of the different joints.
For tool joints and some other threads, probably the best book available is “What Keeps Your String Together”. This book is published by Joy Manufacturing Co. and is available at their stock points.
Tubing tables are available several places. Brown Oil Tools and Baker Oil Tools both publish a very good book on tubing. They will usually give you one or you may also write to: Gulf Publishing Company, Reprint Dept., World Oil, P.O. Box 2608, Houston, TX, 77001.
Washpipe information is best acquired from the Fishing Tool Company that furnishes the pipe you are using. It is a good idea to know the O.D., I.D., weight per foot, yield strength, and recommended make-up torque on any string of washpipe that you have on a job.
Information on casing can be found in the composite catalog under the manufacturer’s listing.
Line pipe information is listed in the “What Keeps Your String Together”, however, it is not important that you know a great deal about it anyway.