Click on the links below to access articles from our Drill Rod Safety Series.
Part 1: Manufacture and mechanical properties of drill rod materials
Since all downhole tools are manufactured from tubular steel, it is necessary that we all have a good appreciation of the mechanical properties, design parameters, modes of failure and therefore the limitations of commonly used tubular steel products.
This is the first in a series of three articles in which some of the more important issues involved in the design, manufacture and use and abuse of drill rods will be outlined. It is not intended that these articles be an exercise in mathematics or physics, but discussion of some mechanical concepts is unavoidable – I will try to keep the discussions as simple as possible.
To a large extent, I use diamond drill rod to illustrate several the principles of design, but the principles discussed can be applied to all drill rods and drillpipe used in all methods of drilling.
What forces and stresses are exerted on drill rods? Here's an explanation of the mechanical concepts.
The tubular steel used to manufacture drill rods must meet strict manufacturing standards and have specific mechanical properties.
How are drill rods and drillpipe manufactured, and which grades of steel are used?
A demonstration of the cold drawing procedure for manufacturing steel tubing.
Part 2: Depth rating of drill rods and thread design
In Part 1 of this series, we examined how seamless steel tubing is manufactured as well as its mechanical properties. This is Part 2 of the Drill Rod Safety Series and these articles examine the depth limitations of drill rods and the characteristics of different types of threads used on drill rods and drill pipe.
What is the link between yield strength and depth rating? Find out more about this interesting relationship here.
For a thread to fail, it is necessary that the flanks of the threads are deformed to such an extent that the box and pin are able to move apart.
The first wireline drill rod thread was developed in the 1950's. Find out what has changed since then and what these developments mean for your drilling operation.
Part 3: Causes of drill rod failure
In the third part of this series we examine a very important aspect of a drilling operation - the failure of drill rods or drillpipe.
In diamond drilling operations, the drillstring is rotated at extremely high rotational speeds and the consequences of a drill rod failure can be catastrophic particularly if the drill rod that fails is a quillrod.
Read this article to gain an understanding of the modes of failure of drill rods.
The quillrod is an irreplaceable part of a drilling operation, therefore a thorough understanding of the causes of quillrod failure is essential in preventing these incidents.
Pro-active detection of potential drill rod failure should be a key element of day-to-day drill site safety management, however, quillrod management is complicated by the different procedures used by different contractors.
Drill rods and drill pipe are an extremely expensive part of the drilling operation and so correct break in and maintenance procedures are essential for long life.