Drilling Line Inspection: Five Broken Wires Before the Trip Is Finished
During a trip out of hole at 2,100 m, the derrickman reports a rhythmic popping from the drilling line. Inspection of the 1½ in 6×19 IWRC line finds five broken wires spread over one rope lay about 12 m above the deadline anchor, one broken wire at the poured socket, and a measured diameter 1/16 in below nominal at the worst point. The line has accumulated 3,250 ton-miles since the last slip-and-cut; the rig standard calls for slipping and cutting every 800 ton-miles. Four wraps remain on the drum and the deadline anchor shows no movement. The block is standing in the derrick with the elevators empty. The trip is 12 hours behind schedule and the company man wants to finish before slipping the line.
1. Assess the line against the inspection findings and the rig standard. Is it acceptable to complete the trip? Give the reasoning behind your decision.
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The line is not acceptable for continued service. Four separate findings support that conclusion:
- A broken wire at the poured socket is a termination defect. A termination is a high-stress point and a broken wire there is not treated as ordinary random wire breakage; the affected length should be cut off and the line re-terminated.
- Five broken wires in one rope lay is at or near the removal threshold commonly applied to 6×19 construction (six random broken wires in one lay, or three in one strand). Even if it falls just below a random-wire count, it is combined with the termination defect and diameter loss, so the combined condition governs.
- The diameter is 1/16 in below nominal, which is significant local wear or core deterioration for a 1½ in line. Confirm against the manufacturer and API RP 9B guidance, but do not treat it as serviceable while the cause is unexplained.
- The line is four times past its 800 ton-mile slip-and-cut interval, and only four wraps remain on the drum. Both increase the risk of fatigue failure and loss of friction at the drum.
The popping the derrickman heard is consistent with wire failure or poor spooling, not normal running. Completing the trip would keep a damaged line under load with a heavy block in the derrick. Stop the trip, secure the block and slip and cut the line.
2. Describe how you would carry out the slip-and-cut safely and what you would check before returning to operations.
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Stop drilling and tripping, inform the drill floor and toolpusher, and barricade the deadline and drum area. Secure the travelling block so the line is not under working load, and confirm the brake is set and the block is restrained.
Use trained personnel with gloves, eye protection and cut-resistant sleeves. Mark the cut length and the reference point before releasing anything. Control the free end with a tag line and keep everyone out of the bight and away from the line path. Release the deadline anchor in a controlled way, pull the required length through so that the worn section is removed, and re-anchor with the correct number of dead wraps and the specified tension. Cut with a sharp rope cutter; do not cut a line under tension.
Before returning to operations, check:
- at least five wraps on the drum as required by the rig procedure, with no crossovers or slack spooling;
- the new length is free of broken wires, kinks and corrosion;
- the socket is properly poured or re-terminated and the anchor is tight;
- the ton-mile counter is reset and the cut length and position are recorded.
Run the block slowly through a few cycles and inspect spooling before loading the line again.
3. The company man repeats that the trip must be finished. What records would you make and how would you handle the instruction?
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Record the time and date, ton-miles since the last cut, the 800 ton-mile standard, the number and location of broken wires, the socket defect, the measured diameter, drum wraps and the decision to stop. Attach photographs if permitted and note who inspected the line. Record the slip-and-cut length, new anchor arrangement, post-cut inspection and the name of the person who authorised the return to service.
Handle the instruction by stating the consequence plainly: a line failure can drop the block, sever the line and injure or kill crew in the derrick or on the floor. The line is outside the rig's own cut interval and has a termination defect. Exercise stop-work authority, inform the toolpusher and rig manager, and ask the company man to put a contrary instruction in writing. Do not resume tripping until the line is cut and inspected and the responsible supervisor accepts it. This is a safety-critical inspection finding, not a scheduling preference, and the record protects both the crew and the driller if the instruction is disputed later.