Riser tensioners · Wireline units with 120–280 kips per tensioner, 12.5 ft cylinder stroke and 50 ft wire travel at 3,000 psi, and N-line direct cylinder systems rated 1,800–4,800 kips at midstroke with 50 ft stroke
A riser tensioner keeps a marine drilling riser in tension while the floating rig heaves, so the riser string hangs from the rig rather than standing on the seabed. Wireline tensioners pull on wire ropes running over sheaves to a tension ring on the riser; N-line or direct cylinder systems hang the cylinders from the rig and attach them to the tension ring directly. Ask three things first: what total tension the riser needs, how much heave the stroke must cover, and what accumulator, air supply and control interfaces the rig provides.
Riser tensioning systems for marine drilling risers on floating rigs: wireline tensioner units, idler sheaves and wire ropes, N-line or direct-acting tension cylinders, air/oil accumulators and gas pressure vessels, air control skids and control panels. The riser joints and buoyancy (see marine riser system), subsea BOP stacks (see blowout preventer bop), drill string heave compensators and production riser tensioners on fixed platforms are outside this page.
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NOV describes the wireline tensioner as providing positive tension to the marine riser and compensating for the relative motion between the riser and the drilling rig. Tensioners are installed diametrically opposite each other, so that reducing tension in one unit does not put lateral force on the riser tensioner ring. Each support wire runs from the support ring on the riser over pivot-hinged idler sheaves and fixed lead-in sheaves, around double sheave assemblies on each end of the cylinder, to a wire rope anchor; the four-to-one reeving turns a 12.5 ft cylinder stroke into 50 ft of wire travel. [1]
NOV's wireline models (WRT-120 to WRT-280) are rated 120, 200, 225, 250 and 280 kips dynamic capacity per tensioner, arranged as 4, 8 or 16 single or dual units, with single-unit weights of 14 to 32 t and dual-unit weights of 23 to 67 t. [1] A Cameron patent explains that a conventional wireline set serves one wellhead, and that serving a second well needs the tensioners moved, skidded or slid, or direct-acting cylinders; it proposes routing the cables through turning sheaves to reach a second tension ring. [2]
NOV's N-line system consists of six tension cylinders with gas/oil accumulators, anti-recoil valves, an air control skid, remote and local control panels, PLC and air pressure vessels (APVs); the cylinders hang from single supports and connect to a tensioner ring furnished by others. Its NRT models are rated 1,800, 3,600, 4,200 and 4,800 kips (8,007 to 21,352 kN) maximum tension at midstroke, with a 15.24 m (50 ft) stroke and installed weights of 268 to 298 t, and NOV states the system can operate on 4 cylinders. [1]
Editorial calculation: 120 kips is about 534 kN and 280 kips about 1,245 kN; 1,800 kips over six cylinders is 300 kips (about 1,334 kN) per cylinder; 3.81 m × 4 = 15.24 m. [1]
Give the supplier the rig type and moonpool layout, riser size and water depth, required total and per-unit tension, heave to be compensated, number of wells to serve, available air supply and deck space, required anti-recoil and control interfaces, design temperature, and certification needs.
02
NOV's wireline tensioners run at 207 bar (3,000 psi) maximum operating pressure, with working air pressure vessel volumes of 2,000 to 5,800 l per cylinder depending on model, individual standby APVs, two 138 Nm³/h compressors, and a design temperature of −20 °C to +45 °C. A fluid connection block sits between the accumulator and cylinder, and the accumulator gas side connects to a gas reservoir to hold riser tension constant. [1]
Control equipment for the wireline system is one or two air control skids, a PLC control panel and a remote control panel, with the driller's panel used to start, operate, monitor or shut down the system. For N-line systems NOV lists standard gas volumes of 76,800 or 114,600 l, 8 in hose connections, a design temperature of −20 °C to +55 °C, an integrated piston rod position system, and an anti-recoil system. [1]
Editorial calculation: 207 bar is 20.7 MPa; 14 t is 14,000 kg. [1]
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No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
Ask any supplier for rated tension per unit and per system, stroke and wire travel, maximum operating pressure, accumulator and APV volumes, unit weights, anti-recoil design, control system architecture and interfaces, design temperature, wire rope size and sheave diameters for wireline units, certification to the applicable standard, and service and inspection support.
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This is a functional reference built from the sources cited; it is not one maker's specification.
| Part | Role | Fix in the order |
|---|---|---|
| Tensioner cylinder | Strokes to hold tension as the rig moves. [1] | Stroke; rating. |
| Air/oil accumulator and APVs | Store gas to keep tension constant. [1] | Volumes. |
| Wire rope and sheaves (wireline) | Carry tension to the ring at 4:1. [1] [2] | Rope dia.; sheave dia. |
| Tension ring | Connects tensioners to the riser. [1] | Interface. |
| Anti-recoil valves | Control riser recoil (N-line). [1] | Function. |
| Air control skid, PLC, panels | Start, operate, monitor, shut down. [1] | Interfaces. |
| Rod position system | Monitors each piston rod (N-line). [1] | Signals. |
05
A tensioner quotation needs values for your rig and riser. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Rated Tension Capacity (kN) | e.g. 120–280 kips per wireline unit; 1,800–4,800 kips (8,007–21,352 kN) per N-line system. [1] | Per unit and total. |
| Stroke Length (m) | e.g. 3.81 m cylinder / 15.24 m wire travel; 15.24 m N-line. [1] | Stroke. |
| Operating Pressure (MPa) | Not stated in the reviewed sources. | Normal pressure. |
| Maximum Working Pressure (MPa) | e.g. 207 bar (3,000 psi) wireline. [1] | Max pressure. |
| Operating Temperature (°C) | e.g. −20 to +45 °C wireline; −20 to +55 °C N-line. [1] | Range. |
| Cylinder Bore Diameter (mm) | Not stated in the reviewed sources. | Bore. |
| Rod Diameter (mm) | Not stated in the reviewed sources. | Rod. |
| System Weight (kg) | e.g. 14–32 t single, 23–67 t dual; 268–298 t N-line installed. [1] | Weights. |
| Accumulator Volume (L) | e.g. 2,000–5,800 l APV per cylinder; 76,800 or 114,600 l gas. [1] | Volumes. |
| Response Time (s) | Not stated in the reviewed sources. | Response. |
| Control Voltage (V DC) | Not stated in the reviewed sources. | Supply. |
| Ingress Protection | Not stated in the reviewed sources. | IP rating. |
| Corrosion Protection | Not stated in the reviewed sources. | Coating system. |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Rig: [type; moonpool; wells served] Riser: [size; water depth; mud weight] Tension: [total; per unit] Type: [wireline; direct cylinder] Stroke: [heave; wire travel] Pressure and gas: [max pressure; APV volume; air supply] Controls: [panels; PLC; anti-recoil] Certification: [standard; inspection]
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NOV says it keeps positive tension on the marine riser and compensates for the relative motion between riser and rig. [1]
NOV's wireline units use four-to-one reeving, so 12.5 ft of stroke gives 50 ft of wire travel. [1]
In NOV's design, six cylinders hang from the rig and connect directly to the tensioner ring, with accumulators and anti-recoil valves. [1]
Sources checked 2026-10-11. NOV makes wireline and N-line riser tensioners; Cameron holds a patent on wireline riser tensioner cable routing.
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