In modern maritime operations, protecting seawater piping and cooling systems from marine growth such as barnacles and algae is essential to maintaining efficiency and reducing maintenance costs. The Marine Growth Preventing System (MGPS) is a widely used electrochemical solution, and among its well-known variants is the “Chlorine Attacker - DS”, manufactured by Yokohama Denco
1. Working Principle
The system operates by electrolyzing seawater, producing two active biocidal agents:
- Chlorine (Cl₂)
- Hypochlorite (NaClO)
These agents are injected into the sea chest, then carried through the ship’s seawater lines, where they effectively prevent the growth and attachment of marine organisms on internal surfaces such as valves, heat exchangers, and piping.
2. System Components and Basic Operation
Main components of the “Chlorine Attacker - DS” include:
- A three-phase rectifier converting AC power to DC (output 2.7 kW kilowatts),
- An electrolytic cell containing electrodes that perform the electrolysis,
- A drain valve for flushing the electrolytic cell during long idle periods,
- A current control knob to adjust chlorine production (too high a dose may accelerate corrosion),
- Sampling points for checking chlorine concentration in seawater.
3. Operational Considerations
- MGPS is not a mandatory system under current international regulations
- Shipowners generally require the MGPS to run continuously during vessel operations.
- When using only one sea chest (typically the low sea chest), the MGPS valve on the high sea chest should remain partially open (around 20%) to prevent sediment buildup or fouling.
- If the system is idle for an extended period, it is recommended to fully drain the electrolytic cell to avoid scale formation or electrode corrosion.
4. Inspection and Maintenance Requirements
Proper inspection and maintenance of the MGPS system are essential and must follow both the manufacturer’s recommendations and shipowner regulations.
As per Maker’s (Yokohama Denco) Guidelines:
- Electrode cleaning should be carried out every 3 months to maintain electrolysis efficiency.
- Regular inspections for corrosion or rust on power connections and internal components.
- Adjust current settings periodically to optimize chlorine output and minimize the risk of corrosion.
As per Company’s EP-Manual (Biofouling Management Plan):
- Engine room watch officers must perform daily checks on chlorine concentration and system operation.
- The Master is responsible for weekly inspections.
- Chlorine production current values are usual automatically monitored and transmitted to shore via the IMCS system
5. Restriction of using MGPS in port & Recommendations:
- Check local port regulations:
Before arriving at port, verify the local requirements regarding MGPS operation and possible restrictions.
- Follow manufacturer guidelines:
Operate the MGPS in accordance with the manufacturer's instructions to minimize environmental impact.
- Consider eco-friendly MGPS solutions:
Where possible, use systems that do not discharge harmful substances, such as ultrasonic MGPS or non-toxic antifouling methods.
BBC – SMR Marine
Training Department
C/E NGUYEN XUAN HUNG (+84 904 554 152)
