Jack-up Offshore Platform

Jack-up Offshore Platform Bolt Cylinder

The smallest cylinder in the offshore range — but arguably the most critical for safety. A 100 mm bore actuator that drives a steel locking pin into position, mechanically securing a 15,000-tonne platform at height. If the bolt cylinder fails to engage, the platform cannot be locked — and cannot be left at elevation safely.

≤100mmBore

≤60mmRod

32 MPaPressure

Built-inSensor

Technical Specifications

Parameter	Specification
Product Name	Jack-up Offshore Platform Bolt Cylinder
Features	Insert and retract cylindrical pins to lock the ring beam
Bore Diameter	Up to 100 mm
Rod Diameter	Up to 60 mm
Working Pressure	Up to 32 MPa
Sensor	Built-in displacement sensor (reduces installation size)
Application	Jack-up Offshore Platform

How the Bolt Cylinder Locks the Platform at Height

Jack-up Offshore Platform Bolt Cylinder

During jacking, the lifting cylinder (#9) pushes the platform up by one stroke. But hydraulic pressure alone cannot safely hold a 15,000-tonne platform at elevation indefinitely — a hydraulic leak, power failure, or valve malfunction would allow the platform to drop. The bolt cylinder provides the mechanical lock that eliminates this risk.

After each lifting stroke, the bolt cylinder extends its rod (which drives a hardened steel pin) into a matching hole in the ring beam. Once the pin is fully engaged, the platform weight transfers from hydraulic pressure to the mechanical pin — a positive, fail-safe lock that does not depend on hydraulic supply. The lifting cylinder can then safely retract for the next stroke.

The built-in displacement sensor confirms pin engagement to the jacking control system. The lifting cylinder is not permitted to retract until the sensor verifies that the pin is fully seated. This interlock prevents the catastrophic failure mode of retracting the lifter without the pin engaged. Browse the offshore hydraulic cylinder range for the complete jack-up platform system.

Why the Built-in Displacement Sensor Matters

Reduced installation envelope — unlike an external sensor, the built-in sensor occupies no additional space outside the cylinder body. On a jack-up platform where bolt cylinders are packed tightly around each leg, this space saving is significant.
Pin engagement verification — the sensor provides continuous, real-time position feedback to the jacking PLC. The system knows exactly how far the pin has extended — not just "in" or "out" but the precise position in millimetres. Partial engagement (pin not fully seated) is detected immediately.
Maintenance and replacement efficiency — the sensor is accessible through the cylinder end cap for maintenance or replacement without removing the cylinder from the platform. This avoids the time and cost of complete cylinder removal in a congested leg structure.

Bolt Cylinder OEM & ODM

Korea Ever-Power manufactures bolt cylinders for new-build and existing jack-up platforms. Provide the ring beam pin diameter, pin engagement depth, retraction speed requirement, sensor signal type (4–20 mA, 0–10 V, or digital), and classification society requirement. The factory delivers matched bolt cylinder sets with built-in sensors, integrated valves, test certificates, and spare pin assemblies.

Precision hydraulic cylinder manufacturing at Korea Ever-Power

Hydraulic cylinder types for offshore applications

FAQ

How many bolt cylinders does a jack-up platform use?

Each leg has multiple ring beam pin positions. A typical 3-leg platform uses 12–24 bolt cylinders in total. Each pin must engage and disengage reliably under the full platform weight.

What happens if a bolt cylinder fails to engage?

The jacking control system detects incomplete engagement via the built-in sensor and halts the jacking sequence. The lifting cylinder holds the platform at the current position while the bolt issue is resolved. Redundant bolt positions on the ring beam allow continued operation if one pin location is compromised.

What sensor signal types are available?

4–20 mA analog, 0–10 V analog, and digital (SSI, IO-Link) outputs are available. Signal type is selected to match the platform's existing jacking PLC. Korea Ever-Power provides the sensor calibration certificate with each cylinder.

How is the bolt cylinder protected against corrosion?

The bolt cylinder operates inside the leg structure, partially protected from direct wave impact but still exposed to salt air and condensation. Stainless steel piston rod, FKM seals, and marine-grade epoxy coating on the barrel are standard.

Can bolt cylinders be ordered together with lifting cylinders?

Yes — Korea Ever-Power supplies complete jacking system cylinder sets (lifting + bolt) as a coordinated package. This ensures dimensional compatibility, matched sensor specifications, and single-source documentation for classification. Browse mobile machinery hydraulic cylinders and industrial engineering hydraulic cylinders for related heavy-duty applications.

What Our Customers Say

★★★★★Feb 2026

"The built-in sensors on the bolt cylinders eliminated our previous external sensor failures. The external sensors on our old bolt cylinders were constantly damaged by condensation and vibration inside the leg structure. The built-in design has been 100% reliable through 6 jacking cycles."

P. Christiansen — Electrical Superintendent, Danish jack-up contractor

★★★★★Oct 2025

"We ordered bolt cylinders and lifting cylinders as a complete set for a 3-leg jack-up barge. Having a single supplier for the entire jacking system simplified procurement, documentation, and commissioning. DNV certification was handled as one package."

Eng. W. Hoffmann — Project Manager, Germany

★★★★☆Jun 2025

"Good quality bolt cylinders with accurate sensors. The IO-Link digital output integrates cleanly with our Beckhoff automation system. One cylinder sensor needed re-calibration after 12 months — Korea Ever-Power provided the calibration procedure and support remotely."

S. Nakagawa — Automation Engineer, Japan

★★★★★Mar 2025

"Replacement bolt cylinders for a 25-year-old jack-up platform. Korea Ever-Power matched the original pin diameter and engagement depth exactly. The built-in sensor is a significant upgrade over the original mechanical limit switches."

C. Martins — Maintenance Director, Brazilian offshore company

★★★★★Dec 2024

"The stainless steel rods on the bolt cylinders solved the corrosion problem we had with our previous chrome-plated carbon steel rods. Inside the leg structure, the condensation and salt air corroded the chrome within 2 years. The SS rods show zero corrosion after 14 months."

F. Al-Khalifa — Equipment Manager, Bahrain