Category Archives: Filtering equipment

Marine Compressed Air Dryer – Ensuring Efficient Operation and Reliable Maintenance

Posted on by
Reply

Marine compressed air dryers are vital components used aboard ships and offshore platforms to remove moisture and contaminants from compressed air systems. These devices play a crucial role in ensuring the efficient operation of various pneumatic equipment and systems on board. In this article, we will delve into the purpose of a marine compressed air dryer, its correct operation, the significance of regular maintenance, and troubleshooting tips to keep it in optimal working condition.

Example of a control dryer

Purpose of Marine Compressed Air Dryer

The main purpose of a marine compressed air dryer is to eliminate moisture from the compressed air. In a marine environment, humidity is ever-present, and when compressed air is exposed to it, it tends to become saturated with water vapor. When moisture-laden air passes through pneumatic systems and equipment, it can lead to several detrimental consequences:

      • Corrosion of air tools and equipment – moisture in the compressed air can cause rust and corrosion in pneumatic components, pipes, and machinery, leading to premature failure and potential safety hazards.
      • Damage to electrical components – moisture can damage sensitive instruments and controls, causing malfunctions and compromising the overall safety and reliability of the vessel.
      • Reduced efficiency of air tools and equipment – water in the compressed air can hamper the performance of pneumatic tools and systems, leading to decreased productivity and higher operational costs.
      • Increased maintenance costs
      • Health and safety hazards

Correct Operation of Marine Compressed Air Dryer

Control air dryer operating principle is as follow: The humid air flows into the air inlet connection and is pre-cooled in the heat exchanger before it enters the evaporator. As the air passes through the evaporator, which is cooled by the liquid refrigerant, the air temperature drops to 10°C, which is the dew point at which the moisture in the air is condensed. The condensed water is now separated from the air and is purged out of the system through the automatic drain trap. The high pressure liquid refrigerant now passes through the expansion valve and is evaporated in the evaporator, before returning to the compressor to continue the refrigeration cycle. 

To operate a marine compressed air dryer correctly, it is important to follow the manufacturer’s instructions. To ensure the marine compressed air dryer operates efficiently and effectively, follow these guidelines:

      • Proper Installation – install the dryer in a clean, well-ventilated area away from potential sources of contamination, such as chemicals or exhaust fumes. Adequate ventilation prevents overheating and prolongs the lifespan of the dryer.
      • Filtration – prioritize the installation of filtration systems upstream of the dryer to remove larger particles, oil, and other contaminants that could clog the dryer and reduce its performance.
      • Adjust Air Pressure – normally dryer is connected to the compressed air supply line. Set the air pressure within the recommended range as per the manufacturer’s guidelines. High pressures can stress the dryer unnecessarily, while low pressures may result in insufficient drying.
      • Drain Moisture Regularly – most marine compressed air dryers are equipped with automatic drains. Ensure these drains are functional and regularly inspect and clean them to prevent blockages and ensure proper moisture removal.
      • Monitor Performance – regularly check the dryer’s output dew point and pressure levels to verify its efficiency. An increase in the dew point may indicate potential issues that need to be addressed promptly.

Maintenance of a Marine Compressed Air Dryer

To ensure the long life and reliable operation of a marine compressed air dryer, it is important to maintain it on a regular basis. Here are some maintenance practices to follow:

      • Cleaning – clean the dryer’s exterior regularly and ensure that the surrounding area is free from dust and debris that could obstruct air intake vents.
      • Filter Replacement – Follow the manufacturer’s guidelines for filter replacement intervals. Clogged or dirty filters can restrict airflow, leading to decreased performance and increased energy consumption.
      • Heat Exchanger Inspection – Regularly inspect and clean the heat exchanger to prevent a build-up of scale or debris, which can reduce the dryer’s efficiency.
      • Check Drains – Routinely inspect and test automatic drains to ensure they are functioning correctly and effectively removing moisture from the system.
      • Lubrication – If the dryer has any moving parts, ensure they are well-lubricated according to the manufacturer’s recommendations.

Troubleshooting Marine Compressed Air Dryer

Despite proper maintenance, issues may still arise. Here are some common problems associated with marine compressed air dryers and possible troubleshooting steps:

      • Insufficient Drying – if the dew point remains high despite correct settings, check for clogged filters, heat exchanger fouling, or malfunctioning drains. Clean or replace components as needed.
      • Excessive Pressure Drop – a significant pressure drop across the dryer can indicate clogged filters or obstructions in the air passages. Inspect and clean the filters and air pathways to restore normal pressure.
      • Unusual Noises or Vibrations – noises or vibrations may indicate loose components or worn-out bearings. Inspect the dryer and address any issues promptly to prevent further damage.
      • Leakage – check for air leaks around fittings, valves, and connections. Repair or replace damaged components to maintain the dryer’s efficiency.
      • If the dryer is not operating at all – it may have a problem with its electrical connections. In this case, you will need to check the dryer’s electrical connections and make sure that they are properly secured.
      • If you are still having trouble with your marine compressed air dryer, you should contact the manufacturer for assistance.

In conclusion, marine compressed air dryers are indispensable in maintaining the reliability and efficiency of pneumatic systems aboard ships and offshore installations. By understanding the purpose, correct operation, and significance of regular maintenance, operators can optimize the performance and prolong the lifespan of these essential devices. Troubleshooting skills further enable swift identification and resolution of issues, ensuring a smooth and safe marine environment with reliable compressed air systems.

If you want to learn and get a “Diploma in Marine Refrigeration and Climate Control”, please follow THIS LINK on Alison platform. The course is free and all you need to do is just to subscribe to their platform using the link above. This will be of a great help to me as well, as I will earn small commission. You can consider this as a reward for my effort to provide guidance and advices with regard to complex, challenging and rewarding marine engineering. 

If you wish to learn about “Oil in Refrigeration and Air Conditioning Systems”, please follow THIS LINK.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World, Telegram Chief Engineer’s Log Chat or Instagram and will try to answer to all your queries. You can use the feedback button as well!

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published.

Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

What you need to know about Ballast Water Treatment requirements onboard vessels

Posted on by
Reply

Water has been used as ballast to stabilize ships at sea ever since steel-hulled vessels came into widespread usage. In order to keep the operational conditions of the ship at a safe level throughout a journey, ballast water is pumped in. This method decreases the amount of stress placed on the hull, provides transverse stability, enhances propulsion and maneuverability, and compensates for changes in weight brought on by varying levels of cargo load as well as consumption of fuel and water.

In spite of the fact that ballast water is necessary for the safe and effective functioning of modern shipping operations, it has the potential to create significant issues for the environment, the economy, and human health due to the large number of marine species that are transported in it. Bacteria, microorganisms, small invertebrates, eggs, cysts, and larvae of a variety of species are all included in this category. There is a chance that the transferred species will be able to establish a reproductive population in the new environment. If this happens, the species will likely become invasive, which means that it will outcompete the original species and eventually become a nuisance.

In 2004, the International Marine Organization (IMO) approved the International Convention for the Control and Management of Ships’ Ballast Water and Sediments as a means of mitigating the adverse effects of these ecological threats. This Convention attempted to put an end to the spread of aquatic invasive species by imposing regulations on the shipping sector that required them to treat the ballast water carried on their ships. Please follow the link if you want to learn more about IMO Convention and Codes. The course is free and you just need to subscribe.

Any shipping company needs to invest in a ballast water management system of the highest possible caliber. But how exactly do these systems function, and why exactly are they beneficial to your ships? In the following paragraphs, we will examine the significant influence that the treatment of ballast water can have on your ballast system.

There are three approaches to treating ballast water; mechanical, physical or chemical. Mechanical methods would include separation and filtration; physical methods include ozone, electrical currents, or UV radiation, while chemical solutions are biocides or a form of chlorination.

There are so may articles and documentation available online which explains how different types of ballast treatment systems works and every each of you will encounter more or less of these types during your sea time. It is important to know that the systems usually comprises of a combination of methods mentioned above. Here there is a short overview of different technologies:

      • Filter and UV – Before subjecting the water to UV sterilization, these systems first remove larger organisms and particulate matter. In most cases, filters will perform a back flush on their own whenever a certain differential pressure is surpassed. The organisms are killed or rendered inactive by the UV light because it causes damage to their DNA, which prevents them from carrying out essential cellular tasks. The ocean water is subjected to filtration and UV treatment before being used for ballasting; after being used, the water is subjected to a second round of UV treatment.
        These systems do not produce any byproducts that are hazardous to the environment, and they are not affected by the temperature or the salinity of the water. If the saltwater has a low UV transmittance, then an increased amount of energy will be required to achieve the same UV goal dose.
      • Filter and Electrolysis – These systems filter the particulates and the bigger organisms before active substances generated from the electrolysis are injected into the ballast water. The electrolysis can be installed inline or in a side stream, where the disinfectant breaks down the cell membranes of the organism. Some system uses a higher dose of active substance without filter.
        The active substances are produced through oxidation of seawater in the electrolysis chamber. Electrolysis also produces hydrogen gas which shall be correctly handled for safety of the ship. During ballasting, the seawater is filtered, and active substances are injected. During de-ballasting, the active substance is neutralized prior to discharge overboard.
      • Chemical injection – These systems are frequently utilized in conjunction with filtration, however this is not always the case. In order to ensure that the ballast water is disinfected, a chemical solution is injected into it. Before the disinfectant may be discharged overboard, it will first need to be neutralized, regardless of whether it is in liquid or granular form.The chemicals that are utilized have trademarks, and delivery may be restricted to particular ports. Because of the potential danger posed by the chemicals, they must be kept on board in airtight containers. When working with chemicals, it is necessary to have well-trained crews and adhere to stringent safety regulations. When compared to alternative ballast water technologies, these BWMS have a significantly higher cost of operation.
      • Ozone – These systems sterilize by injecting O3, which is produced from the surrounding air. Through its reaction with seawater, oxygen 3 oxidizes and neutralizes aquatic species, thereby contributing to the production of effective disinfectants. Although temperature and salinity are not obvious factors affecting the efficiency of these BWMS, a longer holding time may be necessary in some cases. Prior to discharge, residual by-products are required to have their acidity neutralized. Because ozone is toxic, there must be additional precautions taken, and the crew must undergo training.

As you may be aware each vessel must carry an approved Ballast Management Plan. The Ballast Water Management Plan (BWMP) is the document that details the procedure for the discharge of ballast water and the handling of sediment in accordance with regulation D-1 (exchange), and/or regulation D-2 (treatment), and regulation B-5 (sediment management). Conducting ballast water discharge and the cleaning of sediments in accordance with the BWMP ensures compliance with regulations D-1 or D-2, and B-5.

The D-2 standard becomes mandatory for all existing vessels at completion of the first IOPP renewal on or after 8 September 2019. Vessels keel-laid or having underwent a major conversion after 8 September 2017 (EIF date) shall comply with the regulation D-2 upon delivery.

In case of system malfunction the vessel must contact the port authority and flag state administration immediately to discuss contingency measures as per  IMO guidance circular on contingency measures BWM.2/Circ.62 (see attachment below).

The IMO has established a generic guidance in BWM.2/Circ.62 for situations where ballast water to be discharged from a ship is determined to be non-compliant. In such cases, communication between the ship and the port state should occur. The ship and the port state should consider the following as possible contingency measures on a case-by-case basis:

      • Actions predetermined in the BWMP of the ship
      • Discharging ballast water to another ship or an appropriate shipboard or land-based reception facility, if available
      • Managing the ballast water or a portion of it in accordance with a method acceptable to the port state
      • Operational actions,such as modifying sailing or ballast water discharge schedules, internal transfer or ballast water other retention of ballast water on board the ship. The port state and the ship should consider any safety issues and avoid possible undue delays.

Having considered all options above, the ballast water may be discharged in the port or any suitable area, as acceptable to the port state. Port state consideration may include environmental, safety, operational and logistical implications of allowing or disallowing the discharge.

Exchange may be offered as a contingency measure but cannot be performed without permission from the port authority and flag state. The vessel must obtain approval of the exchange method before proposing exchange as a contingency measure.

The discharge of ballast water is subject to any conditions of the port state. In any case, the ship is required to do its best to correct the malfunction of the BWTS as soon as possible and submit its repair plan to the PSC authorities and the flag state.

Some countries, such as the Ukraine and the USA, have stricter requirements than those listed in the convention, therefore it is recommended to familiarize with local requirements prior to conducting discharge of the ballast water in a new port.

When travelling in US waters, the USCG requires that the BWMP contain vessel-specific contingency methods. The BWMP should also include procedures for contacting the Captain of the Port (COTP) and reporting to the National Ballast Information Clearinghouse (NBIC) in the event of a BWTS malfunction. The vessel must contact US authorities as soon as possible and ask for instructions. US regulations require that the vessel inform the nearest COTP, but it is recommended that the destination COTP also be informed. The vessel must have or obtain D-1 certification before proposing exchange as a contingency measure. More information on contingency measures in the USA can be found in the attachment below.

When it comes to any limitations or local prohibitions for chemical treatment systems, it is important to know that the type approval process covers the possibility of toxic discharge according to the IMO and/or USCG standards. Chemical treatment systems are required to satisfy minimum toxicity requirements like all BWTSs.

The requirements related to toxic discharge for different US states are addressed in the 2013 VGP and the US EPA’s Generic Protocol for the Verification of Ballast Water Treatment Technology, known as the ETV Protocol.

The contingency measures chapter is required in the BWMP if the administration of the vessel has decided to implement it or if desired by the owner. In case of BWTS malfunction, well-planned BWM contingency measures allow ship owners to avoid unnecessary downtime for the vessel. The port authority of destination and the flag administration are usually to be informed about the malfunction of the BWTS.

With regard to the query if the vessel can bypass the system during cargo operations in a challenging water port, although the BWTS is fully operational or in the high seas after leaving the challenging port of operation it is important to mention that Ballast Water Management Convention does not allow any bypass unless this is an emergency situation for the vessel.

In case the treatment system cannot be used for ballasting operations due to filter clogging, and there is untreated ballast water in the tanks, contingency measures must be discussed and agreed upon with the port state of destination where the ballast water is planned to be discharged.

Similarly, in case ballasting operations were carried out with alarms indicating that the treatment system is operating outside the system’s performance claim (e.g. UV intensity or TRO is too low), the treated ballast water may not comply with the D-2 standard, and contingency measures must be discussed and agreed upon with the port state of destination where the ballast water is planned to be discharged.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World, Telegram Chief Engineer’s Log Chat or Instagram and will try to answer to all your queries. You can use the feedback button as well!

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source, Credit and Bibliography:

    • DNV Rules and Regulations
    • Youtube video training credit – Marine Online
    • Header picture – Alfa Laval

Links and attachments:

What you need to know about maintenance of hydraulic systems onboard vessel

Posted on by
Reply

Recently I have worked on a vessel where all mooring equipment was hydraulically powered and due age of the vessel we have encountered a lot of trouble with the system (pipe failure, pipe damage, hydraulic hoses and connection failure, pumps’ failures etc.). Apart from this, the vessel was equipped with hydraulically driven cargo cranes which gave us a lot of headache during cargo operation due their age, condition and lack of proper maintenance.

However, the majority of vessel engineers are not familiar with the correct techniques for maintaining hydraulic systems, which is despite the fact that improper maintenance of hydraulic systems is the leading cause of component and system failure. Two different aspects of concern make up the fundamental basis for performing appropriate maintenance on a hydraulic system. The first area is preventative maintenance, which is essential to the success of any maintenance program, regardless of whether it’s for hydraulics or any other piece of equipment for which we rely on its dependability. The second component is corrective maintenance, which, if it is not carried out according to the established protocols, can frequently result in the failure of additional hydraulic components.

As in any other occupational field, knowledge is power and every marine engineer must be proficient in understanding the basic principles of a hydraulic diagram, how is it working, the meaning of hydraulic symbols and the components application and function in the hydraulic system.

Unfortunately, most of the shipping companies don’t spend money for training their engineers in maintenance and troubleshooting of the hydraulic systems. Moreover, the schools and colleges teach their students only general stuff about hydraulic systems, hence the lack of maintenance and troubleshooting knowledge.

Troubleshooting a hydraulic system would take less time and cost less money if we concentrated on reducing the likelihood of system failure in the first place. Instead of selecting not to account for the possibility of hydraulic system failure as the usual, we routinely account for the possibility of such failure. Preventive maintenance of a hydraulic system is very basic and simple and if followed properly can eliminate most hydraulic component failure.

Here on this post I will describe the best maintenance practices for main components of hydraulic systems, practices based on my experience and knowledge which I hope that will help you to learn and understand the importance of these systems preventive maintenance.

The hydraulic reservoirs are used to store a volume of oil, dissipate heat from the fluid and remove contamination from the system. In the below video you can learn about their purpose.

As part of maintenance of the hydraulic reservoirs, I would like to emphasize that if any of the following conditions are met…

    • System has been opened for major work
    • Oil analysis states excessive contamination
    • Hydraulic pump fails

…the best best practices are as follow:

    • It is necessary to clean the region under and all around the reservoir in addition to the reservoir’s exterior.
    • Remove the oil from the reservoir using a filter pump and place it in a fresh container that has never been used to store any other kind of fluid.
    • Clean the insides of the reservoir by opening the reservoir and cleaning the reservoir with a “Lint Free” rag.
    • After that, pour clean hydraulic fluid into the reservoir, and then drain the remaining fluid from the system.

For the reservoir air breather which has been mentioned in the above video, it is not recommended that a standard screen breather be utilized in an unhealthy or hazardous environment. Because of the possibility of introducing impurities into a hydraulic system, it is recommended to utilize a filtered air breather with a value of 10 micron.

Example of a hydraulic reservoir air breather

As part of maintenance of the hydraulic reservoirs air breather, I would like to emphasize that the frequency of maintenance is preferred to be based on historical trending of oil samples rather than based on manufacturer’s recommendation.

The best practice is to remove and throw away the filter and never cleaned, washed and reused.

The hydraulic fluid filters are of a two types on a hydraulic system:

    • pressure filter which comes in collapsible and non-collapsible type and where the latter is preferred.
    • return filter which typically has a bypass, which will allow contaminated oil to bypass the filter before indicating the filter needs to be changed.

Same as hydraulic reservoirs air breather, as part of maintenance of the hydraulic filters, I would like to emphasize that the frequency of maintenance is preferred to be based on historical trending of oil samples rather than based on manufacturer’s recommendation and the best practices are as follow:

    • Utilizing a cleaning solution and a set of clean rags, thoroughly scrub the filter housing or cover.
    • Using clean hands, remove the old filter from the filter housing, then place the new filter inside the housing or screw it into place. NEVER allow your hand to touch a filter cartridge. Open the plastic bag and insert the filter without touching the filter with your hand.

With regard to the hydraulic pumps a marine engineers needs to know the type of pump they have in the system and how operates in their systems (e.g. what is the flow and pressure of the pump during a given operating cycle). Because of this information, a marine engineer is able to swiftly solve a system issue and identify potential trends in pump failure.

The pumps must be checked daily, when in service, for any abnormal noises, vibrations and overheating and if and when it is possible for  proper flow and pressure.

The best maintenance practices is to check and record flow and pressure during specific operating cycles; review graphs of pressure and flow and check for excessive fluctuation of the hydraulic system (usually the maker designate the fluctuation allowed).

It is important to note that hydraulic pumps are very sensitive to impurities and their inner working parts are mainly made of brass. Therefore, any kind of system oil contamination must be avoided as will interfere with pump working performance and lifetime.

Example of damaged hydraulic pump pistons

The hydraulic hoses are designed to to allow fluid to flow from one component to another and they are a vital part of keeping hydraulics systems moving. Any type of hydraulic hoses are required to meet stringent standards to accustom pressure points, loads, and also their position demanded. To perform heavy-duty functions, some engineering elements are assumed to confront the forces within and be flexible enough to bend or reach diverging angles.

Example of hydraulic hoses

It is simple to detect problems with your hydraulic hose assemblies if you check the hoses on a monthly basis. These problems could lead to more serious concerns in the future.  A marine engineer must ensure that fluid designed temperature and pressure are not exceeded and all system’s safety features and protections are fully operational. Do not disregard the leakages because the presence of any external leakage indicates that something is wrong. Hydraulic oil is expensive on its own, but if there is a significant leak, additional costs will be incurred due to fines from the Environmental Protection Agency as well as the expense of cleaning up the spill. The fact that a machine operator or technician could easily slip and fall on the remnants of a leaky hydraulic system is another significant cause for concern regarding the level of safety that is there. When threaded pipe couplings, valve seals, and flexible hoses burst or vibrate loose, not only does pressurized hydraulic fluid create a significant risk of fire, but so does pressurized hydraulic fluid.

Example of hydraulic hose failure

A marine engineer must learn to identify potential hazards, like cracks, abrasions in the cover, tight bends or twisting. The cover protects the reinforcements (wire or fabric) from weather and any other environmental hazards. If the wire or fabric is exposed, water and debris can adversely affect the reinforcement by either rusting the wire or, in the case of fabric, allowing water to wick into the system and get behind the coupling where it can cause damage.

Hoses are a relatively insignificant component of hydraulic equipment and machinery, as you are aware; nonetheless, if they are not properly maintained, they may be the source of some of the most significant issues as well as major injuries.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World and will try to answer to all your queries. You can use the feedback button as well!

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source and Bibliography:

  • YouTube video training credit – Marine Online; Lunchbox Sessions; Donaldson Hydraulic; Al Sikander Parts

 

 

What you need to know about Oily Water Separator (OWS)

Posted on by
Reply

The effective cleaning of engine room bilge water is essential to protect the environment and ensure that the ship meets its regulatory obligations. The aim is to remove all of the pollutants from the engine room bilge water, so that only clean water goes into the sea.

The condensate and leakage water collected in the engine room bilges is a mixture of seawater, freshwater, heavy fuel oil, lube oil and other residues.

Although the ways in which various bilge separators work get put in separate categories, in reality of the same processes go on to varying degrees in most types of separators. These ways are:

      • Coalescence – When particles or oil droplets “coalesce” it means that they come together and form one larger droplet which is more easy to separate from water;
      • Flocculation – is a process by which two or more particles aggregate (stick together) without losing their individual boundaries. This can be achieved by using chemical dosing to raise pH as high alkaline promotes flocculation;
      • Gravity – is the process where heavy particles, sludge and dirt, sink to the bottom whilst lighter fractions (oil and scum) float to the top;
      • Centrifugal Force.

The bilge water separators, generally combine these mentioned ways in stages. For example, The TURBULO – MPB Oily water separator operates as a pressure system. The system functions according to the principle of  gravitation supported by oleophilic coalescer inserts called HEC (High Efficiency Coalescer) in the first stage. These coalescer inserts are corrosion resistant and offer a very large surface area at a high free volume. The oily water mixture is passed through the separator by means of a dedicated pump mounted on the first stage. The separated oil is drained out of the collecting space automatically by means of a level control. If the separator is required to process heavy oil, a heating coil is installed in the oil collecting space to support the operation.

Example of coalescer filters inside OWS

The second ‘breaking’ stage utilises mechanically working ‘Hyca Sep’ elements (Hydro Carbon Separation) to separate mechanical emulsions in accordance with IMO-Resolution MEPC 107(49). The ‘Hyca Sep’ elements function by the principle of coalescence.

The bilge separator operates automatically and discharges water overboard or back to the bilge water holding tank depending on the oil content of the discharged liquid and separated oil to the waste oil drain tank. Bilge water is drawn from the bilge main by the attached pump and into the bilge separator where it passes, usually through a two-stage separation process. The separator uses the difference in density and surface tension between oil and water in usually two stages that are housed separately or in the same compartment.

The separator is initially filled with clean water before admitting bilge water.

OWS filled with fresh water after maintenance

The pump supplies the oil water mixture to the first stage where most of the oil is retained. Oil droplets are attracted to the coalescer surface or gravity plates, forming into increasingly larger drops until they float. The coalescer has a very large open pore surface area and a very low pressure loss and is stable against suspended matter found in bilge water, hence these particles have no detrimental effect on the coalescer. This means that the coalescer will still continue to operate effectively even with considerable fouling.
Following separation in the first stage, the water, now with a very low oil content, is passed into the second stage chamber, which contains, usually, a second coalescer filter to separate out any remaining oil particles, leaving water that may now be discharged overboard.
A conductive oil/air sensing probe at the top of the first stage (HEC) chamber constantly monitors the oil level in the separator, the length of the probe’s electrode determining the operating range. When oil (or air) is detected, the valve to the oil drain tank opens and the valve to the second stage chamber closes and the oil is discharged to the oil drain tank. The supply pump remains
running during the oil discharge. When most of the oil has been displaced, the oil sensing probe is again immersed in water and activates the control system to resume the separating operation.
The separator works automatically and will operate as long as there is water in the bilge water holding tank. Heating may be applied to improve separation, but the heater will only operate when the separator is full of liquid. The separator is fitted with sampling valves which allow oil samples to be drawn and enable the oil/water interface level to be determined.

The Oil Content Discharge monitor samples the bilge water as it passes out of the separator. Should the oil content exceed maximum 15ppm, the three-way valve changes the output flow from the overboard discharge to discharge to the bilge water holding tank. An audible alarm sounds to warn the operator of the alarm condition. The 15ppm device setting can be adjusted from 1ppm up to the maximum 15ppm, but cannot be set higher. The monitor sensing element may be, normally flushed through with fresh water when in operation by moving the supply lever from the SAMPLING to the FLUSHING position.
This action automatically operates the three-way valve on the discharge line and returns the water to the bilge holding tank. Nowadays, the monitor contains a memory card recording the monitor readings for a period of 18 months, after which the data is automatically overwritten. The card is not to be removed from the instrument as it records the following information:

      • Time;
      • Date;
      • Oil content greater than 15 ppm;
      • Separator status

Example of an oil monitoring device

The oil content monitor must be checked each month and must be flushed through in order to remove any debris which could influence the reading.

The maximum flow capacity should not be exceeded, as excess flow will prevent effective separation. The bilge pump suction strainer should be kept clean in order to avoid large solid particles entering the separator, as these will have a detrimental effect on the separation process.

It is important to notice that the oily water separator is designed to separate oil from water, not water from oil. Therefore, if the bilge water supply to the separator contains excessive amounts of oil it will render the equipment inoperable and result in unnecessary maintenance.

Same, if the separator uses flocculation chemicals, great  care must be taken when handling the treatment chemicals, as these substances are caustic and can cause chemical burning on contact with skin and will cause severe damage to eyes. The appropriate protective clothing, including eye protection, must be worn when handling the chemicals.

When operating the oily bilge water separator and the overboard oil monitoring
system, the date, quantity and location of the discharge overboard is to be recorded in the Oil Record Book. All pumping operations and discharges are also to be in accordance with the latest MARPOL Regulations, Annex I, Regulations 9, 10, 11 and 16.

Example of an Oil Record Book

The date, operational code and item number needs to be written in appropriate columns and the required particulars should be recorded chronologically in the blank space. For discharges overboard, the ship’s position at the start and end of the discharge should be entered. Each completed operation shall be signed for and dated by the officer or officers in charge of the operation and each completed page must be countersigned by the master of the vessel.

Example on how to record the operation in ORB

Failure to fill in the oil record book in a proper way has led to those onboard and companies being prosecuted.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World and will try to answer to all your queries.

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source and Bibliography:

  • You tube video source and credit: Marine NAV & TECH and Victor Marine

Lube oil treatment and maintenance onboard

Posted on by
Reply

During operation of engines (especially trunk type engines) the lubricating oil will gradually be contaminated by small particles originating from the combustion and, in particular engines operated on heavy fuels which will normally increase the contamination due to the increased content of carbon residues and other contaminants (about four stroke lubricating system you can read in here).

Contamination of lubricating oil with either freshwater or seawater can also occur.

A certain amount of contaminants can be kept suspended in the lubricating oil without affecting the lubricating properties, but the condition of the lubricating oil must be kept under observation, on a regular basis, by analyzing oil samples.

The moving parts in the engine are protected by the built-on duplex full-flow lubricating oil filters, where usually the replaceable paper filter cartridges in each filter chamber has a fineness of 10-15 microns. The safety filter, at the centre of each filter chamber, is a basket filter element, with a fineness of 60 microns (sphere passing mesh).

Example of lube oil duplex filters

The pressure drop across the replaceable paper filter cartridges is one parameter indicating the contamination level. The higher the dirt content in the oil, the shorter the periods between filter cartridge replacement and cleaning.
The condition of the lubricating oil can be maintained / re-established by exchanging the lubricating oil at fixed intervals or based on analyzing oil samples.

For engines exclusively operated on MDO/MGO is recommended to install a built-on centrifugal bypass filter as an additional filter to the built-on full flow depth filter.

Example of centrifugal filter installed on engine

It is advisable to run lube oil separator units continuously for engines operated on MDO/MGO as separator units present the best cleaning solution. Mesh filters have the disadvantage that they cannot remove water and their elements clog quickly.

The engines operated on HFO (heavy fuel oil) require effective lubricating oil cleaning and in order to ensure a safe operation it is necessary to use supplementary cleaning equipment together with the built-on full flow depth filter. In this case it is mandatory to run lube oil separator units continuously, so that the wear rates are reduced and the lifetime of the engine is extended.

Example of a lube oil purifier

  • As a result of normal operation, the lubricating oil contains abraded particles and combustion residues which have to be removed by the lube oil purifying system and to a certain extent by the duplex full-flow lubricating oil filter as well.
    With automatic mesh filters this can result in an undesirable and hazardous continuous flushing. In view of the high cost of cleaning equipment for removing micro impurities, this equipment is only rated for a certain proportion of the oil flowing through the engine since it is installed in a bypass.For cleaning of lubricating oil the following bypass cleaning equipment can be used:

      • Separator unit
      • Self cleaning automatic bypass mesh filter
      • Decanter unit
      • Built-on centrifugal bypass filter

The cleaning equipment must be operated continuously when the engine is in operation or at standstill and is mandatory during engine operation, as an optimal lubricating oil treatment is fundamental for a reliable working condition of the engine.

In case full flow filtration equipment is used, this is installed as in-line cleaning upstream to the duplex full-flow lubricating oil filter, built onto the engine.

If the lubricating oil is circulating without a separator unit in operation, the lubricating oil will gradually be contaminated by products of combustion, water and/or acid and, in some instances cat-fines may also be present. Therefore, in order to prolong the lubricating oil lifetime and remove wear elements, water and contaminants from the lubricating oil, it is mandatory to use a lube oil purifier unit.
The separator unit will reduce the carbon residue content and other contaminants from combustion on engines operated on HFO, and keep the amount within recommendation, on condition that the separator unit is operated according to manufacturer’s recommendations.

When operating a cleaning device, the following recommendations must be observed:

      • The optimum cleaning effect is achieved by keeping the lubricating oil in a state of low viscosity for a long period in the separator bowl.
      • Sufficiently low viscosity is obtained by preheating the lubricating oil to a temperature of 95°C – 98°C, when entering the separator bowl.
      • The capacity of the separator unit must be adjusted according to manufacturer’s recommendations. Slow passage of the lubricating oil through the separator unit is obtained by using a reduced flow rate and by operating the separator unit 24 hours a day, stopping only for maintenance, according to maker’s recommendation.
      • The heater can also be used to maintain an oil temperature of at least 40 ºC depending on installation of the lubricating oil system.

With multi-engine plants, one separator unit per engine in operation is recommended,

but if only one separator unit is in operation, the following layout can be used.

If a separator unit is installed, with one in reserve, it is possible, for operation of all engines through a pipe system, which can be carried out in various ways. The aim is to ensure that the separator unit is only connected to one engine at a time, thus there will be no suction and discharging from one engine to another. It is recommended that inlet and outlet valves are connected so that they can only be changed over simultaneously.

With only one engine in operation there are no problems with separating, but if several engines are in operation for some time it is recommended to split up the separation time in turns on all operating engines. With 2 out of 3 engines in operation the 24 hours separating time must be split up in around 4-6 hours intervals between changeover.

In order to ensure that the centrifugal forces separate the heavy contaminants in the relatively limited time that they are present in the separator bowl, as stated above the inlet temperature of 95-98°C for lubricating oil must be kept. A control circuit including a temperature transmitter and a controller with accuracy of ±2°C is usually installed and it is essential to keep the incoming oil temperature to the separator unit steady with only a small variation in temperature allowed (maximum ±2°C). The position of the interface between oil and water in the separator bowl is a result of the density and the viscosity of the oil, which in turn depends on the temperature.

It is known that separation efficiency is a function of the separator unit’s flow rate. The higher the flow rate, the more particles are left in the oil and therefore the lower the separation efficiency. As the flow rate is reduced, the efficiency with which particles are removed increases and cleaning efficiency thus improves. It is, however, essential to know at what capacity adequate separation efficiency is reached in the specific case.

In principle, there are three ways to control the flow:

      • Adjustment of the built-in safety valve on the pump. This method is NOT recommended since the built-on valve is nothing but a safety valve. The opening pressure is often too high and its characteristic far from linear. In addition, circulation in the pump may result in oil emulsions and cavitation in the pump.
      • A flow regulating valve arrangement on the pressure side of the pump, which bypasses the separator unit and re-circulates part of the untreated lubricating oil back to the treated oil return line, from the separator unit and NOT directly back to the suction side of the pump.

The desired flow rate is set manually by means of the flow regulating valve. Further, the requirement for backpressure in the clean oil outlet MUST also be fulfilled, helping to maintain the correct interface position.

Proper maintenance is an important, but often overlooked operating parameter that is difficult to quantify. If the bowl is not cleaned in time, deposits will form on the bowl discs, the free channel height will be reduced, and flow velocity increases. This further tends to drag particles with the liquid flow towards the bowl’s centre resulting in decreased separation efficiency.

Oil seldomly loses its ability to lubricate (to form a friction-decreasing oil film), but it may become corrosive to the steel journals of the bearings in such a way that the surface of these journals becomes too rough and wipes the bearing surface. In that case the bearings must be renewed, and the journals must also be polished.

The corrosiveness of the lubricating oil is either due to far advanced oxidation of the oil itself (TAN) or to the presence of inorganic acids (SAN). In both cases the presence of water will multiply the effect, especially sea water as the chloride ions act as an inorganic acid.

If circulating oil of inferior quality is used and the oxidative influence becomes grave, prompt action is necessary as the last stages in the deterioration will develop surprisingly quickly, within one or two weeks. Even if this seldomly happens, it is wise to be acquainted with the signs of deterioration.

These may be some or all of the following:

      • Sludge precipitation in the separator unit multiplies;
      • Smell of oil becomes acrid or pungent;
      • Machined surfaces in the crankcase become coffee-brown with a thin layer of lacquer;
      • Paint in the crankcase peels off or blisters;
      • Excessive carbon is formed in the piston cooling chamber.

In a grave case of oil deterioration the system must be cleaned thoroughly and refilled with new oil.

At normal service temperature the rate of oxidation is insignificant, but the following factors will accelerate the process:

      • High temperature
        If the coolers are ineffective, the temperature level will generally rise. A high temperature will also arise in electrical pre-heaters if the circulation is not continued for 5 minutes after the heating has been stopped, or if the heater is only partly filled with oil.
      • Catalytic action
        Oxidation of the oil will be accelerated considerably if catalytic particles are present in the oil. Wear particles of copper are especially harmful, but also ferrous particles and rust are active. Furthermore, the lacquer and varnish oxidation products of the oil itself have an accelerating effect. Continuous cleaning of the oil is therefore important to keep the sludge content low.

If the TAN is low, a minor increase in the fresh water content of the oil is not immediately detrimental while the engine is in operation. Naturally, it should be brought down again as quickly as possible (below 0.2% water content, which is permissible). If the engine is stopped while corrosion conditions are unsatisfactory, the crankshaft must be turned ½ – 3/4 revolution once every hour by means of the turning gear and you must make sure that the crankshaft stops in different positions, to prevent major damage to bearings and journals. The lubricating oil must be circulated and separated continuously to remove water.

Water in the oil may be noted by steam formation on the sight glasses, by appearance, or ascertained by immersing a piece of glass or a soldering iron heated to 200-300°C in an oil sample. If there is a hissing sound, water is present. If a large quantity of water has entered the lubricating oil system, it has to be removed, either by sucking up sediment water from the bottom, or by replacing the oil in the sump.

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source and Bibliography:

  • Alfa Laval purifying system
  • Westfalia purifying system
  • MAN Diesel & Turbo Service letter SL13-582/KEL

What is Marine Growth Protection System (MGPS) and its purpose?

Posted on by
2

For a variety of reasons, ships rely on the seawater in which they move and one of the primary functions of seawater is to keep the engine and other sections of the ship cool while they are running. The utilized seawater is then discharged back into the sea, and additional seawater is taken in, resulting in a continual flow of salt water exchange between the ship and its surrounding aquatic environment. Despite its benefits, the negative is that seawater contains marine species (both macro and micro), some of which are visible to the naked eye and the majority of which are not. Marine organisms are deposited on the ship’s surface as seawater travels through the different pipelines and sections of the engine. Over time, the deposit accumulates, lowering the effectiveness of the ship’s systems and, in severe situations, choking the entire cooling system of the ship’s leading to the engine’s failure.

Sea chest inlet at the vessel hull

Biofouling is the accumulation of aquatic microorganisms, plants and animals on surfaces and structures immersed in or exposed to the aquatic environment. Aquatic organisms may be transferred to new locations and can be harmful and invasive in locations where they do not naturally occur. They can threaten marine environment, human, animal and plant life. Once invasive aquatic species are established in a new location or habitat, they are often impossible to eradicate.

Example of biofouling accumulation on sea water piping

The anti-biofouling system suppresses the growth of micro and macro-fouling on seawater immersed surfaces. The system is designed to safeguards the internal surfaces of enclosed seawater systems, such as pipework, valves, pumps, heat exchangers, and filters.

Marine biofouling and its associated corrosion can occur in two ways:

  • Barnacles, mussels, hydroids, and other organisms can cause macro-fouling, which reduces water flow, blocks piping, and increases corrosion.
  • Micro-fouling is made up of bacterial slime, micro-algae, and other organisms that impair the heat transfer efficiency of heat exchanger surfaces.

Corrosion can be accelerated in two main ways:

  • When biofouling forms on a metal surface, the oxygen content underneath the fouling layer decreases. In areas of metal exposed to oxygenated sea water, this layer becomes anodic. As a result, pitting corrosion occurs beneath the fouling.
  • Corrosion produced by bacterial activity. Sulphate reducing and iron bacteria are organisms that induce corrosion by their biological activities or metabolic byproducts. Such bacteria thrive in low-oxygen environments, such as behind a layer of aerobic fouling species or in deaerated water like that found in oil storage tanks and bilge wells.

There are different systems and methods, with different type of electrodes, which are working in pair and the anodes employed are marine growth (MG) type and trap corrosion (TC) type. In general, the system is based on the simultaneous electrolytic generation of copper ions and chlorine, which reduces the levels of existing macro- and microfouling organisms while preventing the growth of new ones. All existing and proposed environmental regulations are compliant with the copper and chlorine concentrations used.

The most used and known system onboard vessels is Cathelco, K.C. Ltd, Petreco etc.

The MG anodes are manufactured from copper and release ions during electrolysis which combine with those released from sea water form an unsuitable environment for entering organisms. The TC anodes are, usually, manufactured from aluminum for use in a system with predominantly steel pipes. The aluminum anodes in reaction with sea water will form aluminum hydroxide who will act as anti-corrosive barrier on the pipework. Lately, due cutting cost policy all over the places, the TC anodes are mixed metal oxide (MMO) type.

The copper and MMO electrodes are the anodes in the electrical circuit, which is set up between the strainer body and basket and these act as the cathode to the anodes. The current supply to the electrodes is controlled by thyristor current control modules, which are located in the control panel. The control panel also houses the supply transformer and surge suppression circuits, together with all instruments and controls.

Marine Growth Prevention System. Source and credit: Cathodic ME

A pulse dosing technique is used for ensuring the correct conditioning of the sea water. This is achieved by switching the power supply to the electrodes on and off using timers; typically the power supply is on for 3 minutes and then off for 3 minutes. The current supplied to each electrode is adjustable at the current setting potentiometer. The controller has facilities for operating the port or starboard electrodes or both sets of electrodes as necessary. Under normal circumstances the system is set for automatic operation and the current at each electrode is controlled by the controller.

The effectiveness of the system can only be evaluated through examination, and the manufacturers recommend that if after 6 months of operation, the opportunity to examine a strainer, length of pipe, or heat exchanger comes, that this to be done.
If there are symptoms of infestation, increase the current to each anode in the relevant marine suction filter by a maximum of 0.2 amps. If there is no evidence of an infestation, the current can be lowered by up to 0.2 amps. This routine should be repeated at regular intervals, with the current adjusted accordingly.

The anodes have a life expectancy, usually, of 2.5 years. Routine inspection of the anodes and sea strainers will show when replacement is required.

Anodes opened for inspection still in good condition.
Sea chest strainer opened for inspection

The procedure for operating the system is very simple and can resumed as follow:

  • Check that the sea water system is operating and that sea water is flowing through the strainer, either the high or low strainer.
  • Ensure that the selector switch is set to the port or starboard sea suction strainer as required, but it may also be set to the DUAL position if both sea suctions are open.
  • Check if the main breaker switch is set to the ON position and that the POWER ON lamp is illuminated.
  • Set the selector switch to the AUTO position.
  • The protection system timer will start, usually, with the OFF period. When the timer enters the ON period, the indicated currents for the chlorine (MMO) electrodes and the copper electrode should be checked and adjusted if necessary, by means of their individual potentiometers. The timer may be set for off and on periods to suit conditions.
  • If you want to switch off the system, after stopped ensure that the sea water flows through the strainer for a few minutes to ensure any copper, chlorine or hydrogen gas is removed from the vessel.

As mentioned the system is quite simple to operate and doesn’t require extensive maintenance if is operated correctly. There are some precautions that need to consider when operated by the responsible engineer and few of these, but not limited to, are mentioned below:

  • Gases are released at the electrodes; chlorine at the anode and hydrogen at the cathode. It is essential that sea water is flowing over the electrodes whenever the electrodes are supplied with current, in order to flush these gases away. If the sea water pumps are switched off the power supply to the electrodes must also be switched off. If this is not the case the gases can build up resulting in an explosion.
  • The copper electrode and the chlorine (MMO) electrode currents must be set to suit water flow which is influenced by the sea water temperature as a higher sea temperature requires a higher water flow to give the correct cooling capacity.
  • The current settings should be set according to the sea water flow for optimum performance and efficiency. The setting pro rata is given on a table supplied by a manufacturer or shipyard.
  • Care must be taken to ensure that the current at the electrodes is set correctly for the water flow rate. Excessive current will result in rapid wear of the electrodes. Too high a current at the copper electrodes will cause heavy deposits on the sea suction filter element resulting in flow restriction and even greater deposits. The higher the current the shorter the anode life.
  • If the vessel is in fresh or brackish water, the system should be switched off as missing sea water will make it inoperable and the control system may be unable to reach the recommended current setting causing the alarm to activate.
  • During maintenance, before opening the sea chest strainer, make sure that the system is switched off and that the strainer casing is pressure less and water is drained. It happens very often that the sea chest valves are not properly holding, thus making nearly impossible to open the filter and posing a very high risk of flooding if is not handled correctly.

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Thank you!

Why filter’s proper functioning and integrity are so important into vessel’s FO & LO systems?

Posted on by
Reply

Filters remove particles from liquids and gases, decreasing wear and tear on downstream systems and increasing operating stability and dependability. Filters should have a high level of cleaning efficiency, create minimal resistance, have a high impurity pick-up capacity, and be simple to clean. Filters eliminates solids in the flowing media undergoing filtration, almost completely above the filtration limit and with diminished efficiency below the filtration limit. Particles with diameters greater than the mesh size of the filter fineness can be caught and separated, whilst smaller particles gather on the filter’s exit side. These have weak stability, and when subjected to force (for example, in a bearing’s lubricating wedge), they readily dissolve into their original particle sizes, inflicting less harm.

They might be straining filters, gap filters, or membrane filters.

Multimantle type filter
Cartridge type filter
Candle type filters

I’m not going to describe how they’re manufactured, how they work or what they’re composed of since you’ve already learned that in college. Instead, I’d want to discuss their significance and the issues that might arise as a result of their failure.

They are, as you may have guessed, both manually and automatically operated filters.

Lube oil auto filter
Manual duplex filter

Manual filters are fairly basic, and they are utilized in ship operations, namely in ventilation and refrigeration installations, as well as as an indication filter in lubricating oil and fuel oil systems. They are often stacked in parallel of two or more filters, with one filter inactive in each case. A switching handle switches the input and output from active to passive filtering at the same time (lever or wheel). Prior to switching on, the passive filter should be ventilated.

Automatic filters are a group of filters that self-clean the filter surface when a certain differential pressure is reached. All cleaning activities are program-controlled and performed automatically.

Source: BollFilter

Differential pressure is used to monitor the operation of the filter. Cleaning is required with increased differential pressure in the case of manual filters, whilst cleaning occurs automatically when the predetermined differential pressure is reached in the case of automated filters.
The cleaning interval indicates the quantity of pollutants in the liquid to be filtered, and a shortening of the period indicates a continually growing degree of filter soiling. If the time gap between two subsequent cleaning processes is shortened under the same operating circumstances, the filter must be manually cleaned to eliminate clinging contaminants. An increase in the time gap between two subsequent cleaning procedures, on the other hand, indicates filter dysfunction.

Differential pressure indicator malfunction can be a typical failure of the filtering system. If the differential pressure indicator is not properly working, the system or operator cannot monitor the condition of the filter regarding impurities accumulation and can’t asses its condition, until a downstream low pressure alarm is triggered or an emergency shutdown takes place. Sometimes the differential pressure indicator can be repaired if all necessary parts are available onboard.

Source: Bollfilter

In case of residue accumulation there will be a rise in the differential pressure between the filter inlet and outlet and as the differential pressure increases, the downstream system is starved of oil and pressure will drop under a certain preset low limit which will trigger an emergency shutdown of the engine.

Very dirty fuel oil filter candles
Lube oil filter candles

Filter’s surfaces are cleaned by first removing impurities with gas oil, then mechanically cleaning. An efficient and easy way to clean the filter’s surface is by using an ultrasonic method because high frequency vibrations of an exciter are transferred to the filter cloth through a liquid in ultrasonic baths, which will easily remove solid impurities such as oil breakdown products. The vibrations loosen the filth, which is then rinsed away by the liquid. After filters have been rinsed they are air blown from inside out using a special made multi-nozzle pipe tool.

Strongly adhering residues that, like a coat of paint, wrap the individual woven threads of the filter mesh will produce lacquering, which will increase the filter fineness that will lead to an increment of the differential pressure. Lacquering cannot be removed by back-flushing in most cases and requires filters to be removed and mechanically cleaned and sometimes there were situations when filter candles need to be burned out using a flame gas torch in order to melt down the sticky residues. I have met situations when the filter candles were beyond cleaning due hard and strongly adhering lacquering and need to be discarded.

Lacquering on filter candles

Filter mesh damage or rupture lead to a volumetric flow that permit unfiltered fuel or oil to pass through the filter. Moreover, residues that have already been separated can pass through the rupture and will posses a serious danger to the downstream system and can cause serious damage to the engine components. There were situations when the engine bearings were completely destroyed due oil filter damage, when wire mesh goes inside the oil system with the flow. Moreover, with the new common rail system, when everything is controlled by control or servo oil, the oil cleanliness is of the outmost importance as it will lead to serious damage of the engine control valves and system. Similarly with fuel oil filters, when the residues went inside system and destroyed the fuel injection pumps or fuel injector valves. So, when a damage filter is detected it must be immediately replaced and discarded.

The viscosity of the filtered fuel or oil increases as the temperature decreases. In the absence of adequate preheating, the viscosity might rise to the point that passing through the filter is restricted or obstructed. The differential pressure builds to the point where, in the case of automated filters, continual automatic cleaning takes place. The downstream system’s required operating pressure may not be met, resulting in an engine emergency shutdown.

Another typical failure is represented by gasification which takes place when the gas solubility of a liquid decreases as the temperature raises and the pressure falls in the filter. In this case, gas accumulates inside filter casing and is vented or passes into the system, where it can lead to an operating pressure drop resulting in an engine emergency shutdown.

So, in conclusion the proper functioning and integrity of filtering equipment is of the outmost importance for the proper functioning of the lube oil and fuel oil systems onboard vessels. Under no circumstances, damaged equipment should be kept in use and all necessary spare parts must be always available onboard. If for example spares are not available, the slot should not be kept empty and another type of filter or filtering equipment should be made temporary available. Sometimes in critical situations, the filter candles are swapped from lube oil to fuel oil system and vice versa. This must be a temporary measure and should be fixed as soon as possible. You need to keep in mind that the mesh sizes are different for these filters and prior installation need to check if the correct size is installed. This can be found marked on the filter element as per below:

Filter candle marking
Filter candle marking

In the image above the marking are as follow:

In the image above the marking are as follow:

  • 02 – the manufacture month
  • 21 – the manufacture year
  • 1341167 – complete ID number
  • 10 μm – mesh size
  • 10 – manufacture month
  • 03 – manufacture year
  • 25 – the mesh size. As per B&K mesh size 25 = 10 μm

On most of the vessels, especially on fuel oil system, the filtering equipment is build in stages, from fuel transfer pumps having coarse basket type filters to engine final duplex fine filters, all having different mesh sizes and arrangements. Fuel transfer pumps and fuel feed pumps are usually equipped with magnetic basket type filters, used to restrict bigger size ferrous particles.

Coarse basket type filter
Magnetic basket type filter

Needless to say that proper care and maintenance must be carried out according with manufacturer’s instruction manual and/or company’s plan maintenance system. Failure to do so can lead to extended damage of the equipment and vessel’s engines.

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Thank you!