By Colin Rice of Colin Rice Exploration and Training (Pty) Ltd
In a nutshell, the Drill Rod Safety Series discusses a number of important aspects of drill rods from manufacture to thread design to reasons why drill rods fail. The full Drill Rod Safety Series is available at the bottom of this page or you can view it here.
The technical articles that we published in this series covered:
- How to calculate the forces and stresses in drill rods (and why it is important for you to know this)
- The manufacturing process and the mechanical properties of drill rod material - the fascinating video of the cold drawing process for manufacturing steel tubing was particularly popular with our subscribers
- The relationship between the yield strength of the drill rod material and the depth rating of drill rods
- How drill rod threads are designed (and what this means to you on your drill site)
- Why quill rods fail and how to avoid quill rod failure and,
- Care and maintenance of drill rods
So, what does this mean for you and your drill site?
Drill rods represent a significant hazard on all drill sites and failure of a drill rod can have catastrophic consequences for a drilling operation. Generally, if a drill rod fails below ground level the consequences will be a fishing job and probably little else. If, however the drill rod fails above ground level, the consequences can be very much more severe. This is particularly true in the case of a diamond drilling operation where the drill rods are extremely thin walled and the rotational speeds are extremely high. The focus in the drill rod series was therefore very much on diamond core drill rod.
There are a number of reasons why diamond core drill rod will fail and the primary purpose of the drill rod series is to equip our subscribers with the knowledge to detect defects in wireline drill rods before they fail. Drillers, supervisors, safety officers and even geologists must be able to identify potential defects in wireline and other types of drill rod.
PRACTICAL TIPS TO AVOID DRILL ROD FAILURE
- Ensure that all joints are fully made up and are torqued as specified by the manufacturer.
- Ensure that all threads are clean and free of any debris that will affect closure of the joint.
- Ensure that a good quality thread grease is applied to all connections before they are made up.
- Discard any drill rod with a damaged, deformed or galled thread. Remember, despite what anyone will tell you - a damaged wireline thread cannot be repaired.
- Ensure that only OEM manufactured adaptors are used.
- Very carefully inspect the quill rod for surface defects or deformations and immediately discard a quill rod if it has any evidence at all of circumferential notching. Take a look at this article for examples of notching.