Using the Worksheet Q5, sketch the hydraulic system for the two ram steering gear shown. The system should be capable of ensuring that steerage may be maintained should hydraulic pipe failure occur at any point.(10)
A hydraulic system for a two-ram steering gear with safeguards against hydraulic pipe failure
A hydraulic system for a two-ram steering gear with safeguards against hydraulic pipe failure typically employs redundancy and isolation to ensure steerage can be maintained even in the event of a leak or rupture. Here’s a description of such a system:
Key Components:
- Hydraulic Power Units (HPUs):
- Multiple HPUs: The system has at least two independent HPUs, each capable of supplying sufficient flow and pressure to operate the steering gear on its own. 1. Steering Gear Hydraulic Systems – TSPS Engineering Manual – Massachusetts Maritime Academy weh.maritime.edu
- Redundancy: This redundancy ensures that even if one HPU fails, the other can take over, maintaining steerage.
- Cross-connected: The HPUs are typically cross-connected, allowing either HPU to supply either ram or both rams in case of a failure.
- Rams:
- Two Rams: The system uses two hydraulic rams connected to the tiller or rudder stock.
- Independent Control: Each ram can be controlled independently, allowing for operation even if one ram or its associated hydraulic line fails.
- Piping and Valves:
- Section Isolation Valves: The hydraulic piping system is divided into sections with isolation valves. This allows for isolating specific sections of the system in case of a leak or rupture, preventing the entire system from losing pressure.
- Check Valves: Check valves are installed to prevent backflow and ensure that hydraulic fluid flows in the correct direction. 1. Understanding Hydraulic Check Valve Types for Your System www.dombor.com
- Pressure Relief Valves: These valves protect the system from overpressure by venting excess fluid if the pressure exceeds a safe limit.
- Control System:
- Automatic Isolation: The control system is equipped with sensors and logic to detect pressure drops or other signs of a leak or rupture in the hydraulic lines. It can automatically isolate the affected section, allowing the remaining part of the system to continue operating.
- Alarms and Indicators: The system provides alarms and indicators to alert the crew of any failures or abnormalities in the steering gear system.
Operation in Case of Pipe Failure:
- Leak Detection: If a hydraulic pipe ruptures or develops a significant leak, the pressure in the affected section will drop rapidly.
- Automatic Isolation: Pressure sensors or other leak detection mechanisms will sense this pressure drop and trigger the automatic isolation system.
- Valve Closure: The isolation valves in the affected section will close, preventing further loss of fluid and maintaining pressure in the rest of the system.
- Continued Operation: The remaining HPU and ram(s) will continue to operate, allowing the vessel to maintain steerage, although possibly at a reduced rudder speed or with limited maneuverability.
- Alarm and Crew Response: The control system will activate alarms to alert the crew of the failure. The crew can then take appropriate action, such as reducing speed, initiating repairs, or switching to the emergency steering system if necessary.
Benefits of this system:
- Enhanced Safety: Ensures steerage can be maintained even in the event of a hydraulic pipe failure, reducing the risk of accidents or loss of control.
- Redundancy: The multiple HPUs and independent control of rams provide redundancy and backup in case of component failures.
- Operational Flexibility: Allows for isolation and repair of faulty sections without completely shutting down the steering gear.
Key Maintenance Considerations:
- Regular Inspections: Regularly inspect all hydraulic lines, fittings, and components for signs of wear, corrosion, or leaks.
- Pressure Testing: Periodically pressure test the system to ensure its integrity and identify any potential weak points.
- Valve Maintenance: Ensure isolation and check valves are functioning correctly and are free of debris or obstructions.
- Hydraulic Fluid Condition: Maintain the hydraulic fluid’s cleanliness and proper level to prevent contamination and ensure optimal system performance.
By incorporating these design features and maintenance practices, a two-ram steering gear system with safeguards against hydraulic pipe failure can provide a high level of reliability and safety, crucial for navigating a vessel, especially in challenging conditions.