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Drilling Operations
Rotary Tables
Rotary Tables sit in the drill floor at well centre and seat the master bushing and slips that hold the string off the hook. The Category covers electric and hydraulic rotary tables, non-rotating rotary support tables, master bushings and insert bowls, and tables with integrated power slips. Spare bearings, gears and drive parts are included.
Operating principle
The table's main bearing carries the string weight when slips are set. A pinion drives a ring gear on the turntable when the table rotates. On a top drive rig the table rarely drills. It holds the master bushing, takes the slip load during connections and tripping, and gives backup rotation for work such as milling or running some tools.
The table's clear opening sets the largest bit, casing hanger or tool that passes through the floor without removing it.
Configurations
- Electric-driven tables with an AC or DC motor and gearbox.
- Hydraulic-driven tables with hydraulic motors, which give high torque at low speed.
- Rotary support tables that do not rotate. They carry slip loads and save the cost and weight of a drive.
- Tables with an integrated power slip or hydraulic master bushing.
- Older tables driven from the drawworks by chain, now rare offshore.
Key specifications
| Parameter | Why it matters | Typical classes or units |
|---|---|---|
| Clear opening | Largest item through the floor | 37-1/2, 49-1/2, 60-1/2 or 75-1/2 in (953, 1,257, 1,537 or 1,918 mm) |
| Static load rating | Must exceed your heaviest casing string | short tons or kN |
| Drive power and torque | Only matters if you rotate with it | hp or kW, ft-lb or kN·m |
| Maximum speed | Backup drilling or milling | rpm |
| Height and footprint | Must fit the drill floor cut-out | in or mm |
| Bushing type | Square drive or pin drive, power slip fit | master bushing and insert bowl sizes |
Standards and certification
API 7K covers rotary tables, rotary bushings, slip bowls and rotary slips, including their static load ratings and the dimensions of openings and master bushings. Table, master bushing and insert bowls from different makers only fit together if they follow the same 7K dimensions or the same OEM system. On a classed rig, the table is part of the drilling plant survey.
Failure modes and inspection
- Main bearing wear and brinelling from shock loads when slips are set hard.
- Contaminated lubricating oil from mud and water that get past the floor seals.
- Gear and pinion tooth wear, pitting and excessive backlash.
- Worn master bushing seat and rotary lock.
- Cracks in the housing around load-bearing areas, found by MPI.
An inspection measures turntable vertical and radial play against OEM limits, checks gear contact pattern and backlash, samples the oil and runs the table under power. A bearing that has already been brinelled shows as rough rotation and noise long before it fails.
Documentation
- API 7K nameplate data with opening and static load rating.
- OEM service history and the date of the last main bearing replacement.
- Oil analysis results and seal replacement records.
- Drive motor test reports, or hydraulic motor records.
- Inspection reports covering the housing and turntable.
Integration and compatibility
Check the floor cut-out dimensions and the table's overall height against your drill floor elevation. The master bushing and insert bowls must match your slips and any power slip system. A driven table needs a power supply or hydraulic circuit and control from the driller's cabin. If you run large casing, check that the opening passes your casing hangers and the bit or underreamer you plan to use.
Refurbishment and recertification
A typical overhaul replaces the main and secondary bearings and seals, inspects or replaces the ring gear and pinion, runs NDT on the housing and turntable, and finishes with a run test. A used table is a reasonable buy because it has few wear parts and turns slowly. The main risks are a bearing damaged by shock loads and a static rating below what your casing programme needs. Unused surplus tables can develop corrosion on bearing races after long storage without oil.
Common offshore makers include NOV and HMH. Check slip and bushing fit against your elevators and slips, and the rating against your top drives and casing loads.
FAQ
Frequently asked questions
What rotary table size do I need?
Choose an opening larger than the biggest casing hanger, bit or tool you must pass through the floor, and a static load rating above your heaviest casing string. Common offshore openings are 49-1/2, 60-1/2 and 75-1/2 in. Check the table height against your drill floor too.
Do I need a driven rotary table on a top drive rig?
Not always. A non-rotating rotary support table carries the slip load during connections and tripping, which is its main job on a top drive rig. Keep a driven table if you need backup rotation for milling, fishing or running tools that need rotation from the floor.
What wears out on a used rotary table?
The main bearing, the ring gear and pinion, the seals and the master bushing seat wear most. Mud and water past the floor seals contaminate the oil and shorten bearing life. Ask for oil analysis and bearing replacement records, and measure turntable play against OEM limits.
Will my existing slips and master bushing fit a used rotary table?
They fit only if the table follows the same API 7K opening and bushing dimensions or the same OEM system. Check whether your master bushing is square drive or pin drive, and confirm the insert bowl sizes. Power slips need a matching seat and control connections as well.
Looking for rotary tables?
Tell us what you need and we will find out what is available. We reply within one business day.