Drilling Line and Rigging

Operating principle

The drilling line runs from a supply reel to the deadline anchor, up over the deadline sheave on the crown, back and forth through the blocks, and over the fast line sheave down to the drawworks drum. The deadline anchor clamps the line on a drum and carries a load sensor that feeds the weight indicator.

The line wears unevenly. Sections at the crown and traveling block sheaves and at the drum crossover points take the most bending. Crews slip new line through the system and cut the worn end off the drum, so no section stays at a critical point for too long.

Configurations

• Drilling line in 6x19 class constructions with an independent wire rope core (IWRC) is common.
• Grades under API 9A include extra improved plow steel (EIPS) and extra extra improved plow steel (EEIPS).
• Lay is usually right regular lay for drilling line.
• Deadline anchors with hydraulic or electronic load sensors.
• Slings, shackles, hang-off lines and safety clamps for derrick and floor work.

Key specifications

Standards and certification

API 9A covers manufacture and testing of wire rope, including grades and minimum breaking force. API RP 9B covers field care and use. It sets minimum design factors, 3 for rotary drilling line and 2 when setting casing or pulling on stuck pipe. It also gives drum and sheave sizes, groove gauges, ton-mile service records, cut-off practice and removal criteria. API 8C covers deadline anchors, and RP 8B covers their inspection. ASME B30.9 covers slings and B30.26 covers shackles and other rigging hardware. Local lifting regulations add their own inspection intervals.

Failure modes and inspection

• Broken wires at the crown and on the drum crossover points.
• Crushing and flattening from poor spooling or worn grooves.
• Corrosion from storage outdoors or dried-out lubricant.
• Kinks and birdcaging from bad handling during reeving.
• Heat damage from friction on the drum or from electric arcs.
• On deadline anchors, clamp and drum wear and load sensor drift.

For unused reels, inspect the outer wraps, the reel flanges and the lubricant condition. For deadline anchors, run MPI on the load-bearing parts and calibrate the sensor against a reference load.

Documentation

• The API 9A mill certificate for each reel, with grade, diameter and tested breaking force.
• Storage history, including whether the reel was kept under cover and off the ground.
• The ton-mile record for line already in service.
• Deadline anchor nameplate data, inspection reports and sensor calibration.
• Sling and shackle certificates with proof test and last inspection dates.

Integration and compatibility

The line diameter must match the drawworks drum grooving and the crown and traveling block sheaves. Breaking force divided by the RP 9B design factor must exceed the fast line tension at your maximum hook load and line count. The reel length must cover the full string-up plus enough spare for your planned slip-and-cut programme. The deadline anchor's load sensor must feed your weight indicator or drilling control system.

Refurbishment and recertification

Drilling line is never refurbished. Used line comes off the rig as scrap or for non-critical work, so buy new or unused surplus line with full traceability. Unused surplus reels stored outdoors can lose their outer layers to corrosion, so ask for photos of the outer wraps and the storage location. Deadline anchors can be overhauled with new clamps and a recalibrated sensor. Rigging should be bought unused or with certificates still within their inspection date.

Common line makers include WireCo and Bridon-Bekaert. Naventr can answer questions from the Seller's mill certificates and photos, and pass on your enquiry. Match the line to your drawworks drum and your crown blocks and traveling blocks.