A few years ago, I gave the talk at Groundwater Week in Las Vegas that this series is based on. To prepare, I talked to a few manufacturers. I asked, how often do you require inspection of the wire rope on your drills? Every one of them stated they did not have change-out, rotation or inspection schedules listed in the manuals for their units. The reasoning for this was the liability of giving these recommendations. It would put the manufacturer in the hot seat if an accident occurred and the drill crew had followed manufacturer recommendations.
This lack of guidance from manufacturers puts the liability on drillers and the companies that hire them. The driller must inspect the rig and its components each day and decide if they are safe to run. The CEO or owner must question whether the company thoroughly trains crews with safety in mind. Are our crews making the right choices? Add to this the required documentation: inspections filled out, utilized and retained to develop a company change-out, replacement or rotation schedule. After all wire rope, despite its durability and strength, eventually wears out and must be removed. Regular inspection is crucial.
How Often to Inspect
Visually inspect all hoisting lines at least once each day when in use, as is suggested by American Petroleum Institute (API) RP54 guidelines. Based on the amount of use and misuse, pay daily attention to the condition of all wire ropes. Wire rope is one of the most-used components of the drill rig or pump hoist, therefore is one of the most susceptible to constant wear and tear. Consider any damage or significant wear a potential problem. It is required to know the condition of the equipment before operating the rig or hoist.
The life of a wire rope is dictated by wear, abrasion, kinks, metal fatigue, corrosion and improper reeving. It should not take equipment failure or personal injury to find out your wire rope is deficient. Thoroughly inspect all hoisting lines monthly, making careful records of each month’s inspection.
Beyond monthly inspections, operators should inspect wire ropes likely to be in use during the shift for three categories of apparent deficiencies.
Category I deficiencies might include:
- Significant distortion: Wire rope structure concerns such as kinking, crushing, unstranding, birdcaging, signs of core failure or core protrusion between outer strands.
- Significant corrosion: Rust hides other issues and the true amount of structure loss cannot always be determined.
- Electric arc damage: This could stem from welding or cutting operations, or hot environments such as steel mill work.
- Improperly applied end connections or damaged end connections: Significantly corroded, cracked, bent, or worn end connections (such as from severe service or misuse).
If a deficiency in Category I is identified, an immediate determination must be made by a competent person as to whether the deficiency constitutes a safety hazard. If the deficiency is determined to constitute a safety hazard, operations involving use of the wire rope in question must be prohibited. The wire rope must be replaced or, if the deficiency is localized, the problem corrected by severing the rope in two. The undamaged portion may continue to be used. Joining two or more lengths of wire rope by splicing is prohibited. If a rope is shortened under this paragraph, the employer must ensure that the drum will still have the minimum of two full wraps of wire when the load is in its lowest position.
Other than sand lines, remove wire ropes used as running ropes from service when broken wires meet any of the following Category II criteria:
- For six- and eight-strand constructions, replace when you see six randomly distributed broken wires within one lay length, or three broken wires in one strand within one lay length.
- For rotation-resistant constructions, replace when you see two randomly distributed broken wires in six rope diameters – or four randomly distributed broken wires in 30 rope diameters.
For sand lines, remove those from service when you see three broken wires within one lay length.
When it comes to wire ropes used as standing ropes, such as guy lines, escape lines and pendant lines, remove from service after identifying any of the Category II deficiencies described above. Prohibit any operations involving use of the wire rope in question.
The employer complies with the wire rope manufacturer’s established criteria for removal from service, or a different criteria the wire rope manufacturer has approved in writing for that specific rope. Again, if a rope is shortened the employer must ensure that the drum will still have two wraps of wire when the load and/or boom is in its lowest position.
If a deficiency in Category III is identified, operations involving use of the wire rope in question must be prohibited until the wire rope is replaced! These type of deficiencies include:
- In rotation-resistant wire rope, core protrusion or other distortion indicating core failure.
- Prior electrical contact with a power line.
- A broken strand.
All this may seem like a no brainer until you ask yourself a few questions.
- Are we documenting the inspection of our wire rope and rigging?
- Have I ever said or heard someone say, “It will be ok, run it”?
- Have I ever broken a wire rope?
Answers to these questions will lead you to your conclusion. Wire rope is an amazingly strong machine if we take care of it and use it properly. If we do not take care of it, it will be like that old car you may have had in high school. You never could be quite sure it would get you were you wanted it to. Until next month, stay safe and drill straight.