Night-Shift Inspection Findings on a Top-Drive Rotary Rig
A top-drive rotary rig has been on site for three weeks. At the start of the night shift, the operator reports the following: the rig sits on steel mats over crushed stone; a carpenter's level placed on the mat shows 1.8% cross-slope; the rig's electronic level reads 0.4° out of level; the mast has not been re-plumbed since the mats were reset. A 25 mm 6x19 IWRC hoist rope has two broken wires in one strand within one lay length and a 1.0 mm diameter reduction at a pick-up point. A hydraulic hose on the main winch circuit has a 250 mm longitudinal bulge and a damp fitting. The torque converter temperature is 108°C after 15 minutes at idle in 32°C ambient. The last documented inspection was 9 days ago; the rig has logged 140 hours since.
1. Can the rig start the shift? Prioritize the findings and state what must be corrected before operation.
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No. The rig should not start production until the safety-critical findings are corrected and documented. Prioritize by consequence:
- Hydraulic hose bulge and damp fitting. A longitudinal bulge means the hose reinforcement is separating; a damp fitting is a leak path. On the main winch circuit this can fail suddenly and drop the load or whip. Replace the hose before any lifting or drilling.
- Hoist rope condition. Two broken wires in one strand within one lay length plus a 1.0 mm diameter reduction is a removal-level concern for a hoist rope, especially at a pick-up point. A 1.0 mm reduction on 25 mm is 4%, close to common discard criteria, and the broken wires are localized. Remove the rope from service and have a competent person inspect it against the manufacturer's criteria; do not use it for lifting.
- Level and mast plumb. A 1.8% mat slope is about 1.03°, while the electronic indicator reads 0.4° out. The discrepancy means the indicator or the mat reference is wrong, and the mast has not been re-plumbed. Re-level the mats, re-plumb the mast, and verify with an independent method before drilling. An out-of-plumb mast increases hole deviation and side load.
- Torque converter temperature. 108°C after 15 minutes at idle in 32°C ambient may be abnormal, but the acceptance limit is manufacturer-specific. Check the manual, coolant, fan, and sensor; if it exceeds the limit or continues to climb, shut down and repair.
- Inspection backlog. 140 hours since the last documented inspection exceeds many planned intervals. Complete the full pre-shift and periodic inspection before release.
2. What are the immediate corrective actions, and what documentation should be completed before the rig is returned to service?
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Corrective actions should be sequenced so the rig is not returned to service on a partial fix:
- Lock out and tag the rig; replace the bulged hydraulic hose and repair the damp fitting, then pressure-test and check for leaks.
- Remove the hoist rope and tag it as out of service; install a verified replacement rope and re-reeve correctly. Inspect the sheaves and drum for damage that may have caused the wire breaks.
- Reset or rebuild the mats to a stable, level platform; re-plumb the mast using the manufacturer's procedure; recalibrate or repair the electronic level and confirm against a separate instrument.
- Investigate the torque converter temperature against the manufacturer's limit; check fluid level, cooler, fan, and sensor. Record the actual reading and the resolution.
- Complete the overdue inspection, including the winch, brakes, wire rope, sheaves, mast, pins, hydraulic system, and safety devices.
Documentation should include the inspection checklist with the defects noted, the parts replaced, the rope certificate or traceability, the mast plumb and level readings, the hydraulic test result, the temperature resolution, and the signature of the competent person releasing the rig. The operator should be briefed on the defects and the corrected status. If the rope or hose failure indicates a recurring maintenance problem, add it to the preventive maintenance schedule.
3. The site superintendent says the rig is needed now and proposes running the shift with the hose monitored and the rope used only for light picks. How do you respond?
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Refuse that proposal and explain the failure modes. A bulged main-winch hose can rupture without warning; monitoring does not restore the reinforcement, and a sudden release can drop the load or inject hydraulic fluid. The hoist rope already has localized broken wires and diameter loss; restricting picks to 'light' loads does not remove the damaged section from the load path, and a hoist rope may see shock loads even when the static load is small. The out-of-level mast is also a production and safety issue, not a cosmetic one.
Offer a practical alternative: stop the affected functions, replace the hose and rope, re-level and re-plumb, and inspect. If the schedule cannot absorb that, move in a replacement rig or reschedule the work. Record the stop-work decision and the superintendent's instruction in the site log. Returning the rig to service requires the competent person's release, not a verbal waiver.