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Webinar: Cargo and Cargo Hold Ventilation - Live Q&A with Intercargo and DNV GL
Standard Club, INTERCARGO and DNV GL, the world’s leading classification society, take live audience questions on the recently released 'Cargo and Cargo hold ventilation guide'.
Proper ventilation is essential to preventing damage to the cargo and to ensure the safety of the crew and vessel in bulk carriers. To provide ship’s masters and crew with an understanding of different ventilation requirements for bulk cargoes, Standard Club, INTERCARGO and DNV GL, the world’s leading classification society, have launched a new ventilation guide, available to view in the right-hand panel.
During this live webinar, collaborators of the guide discussed the importance of understanding the most common ventilation systems, how to deal with ventilation problems, emerging claims trends, and take live audience questions on the subject.
- Capt. Yves Vandenborn, Director of Loss Prevention at Standard Club
- Capt. Akshat Arora, Senior Surveyor at Standard Club
- Ed Wroe, Technical Manager at Intercargo
- Morten Lovstad, Vice President, Business Director - Bulk Carriers at DNV GL – Maritime
Watch here. Recorded on Friday 11 December, 2020 at 9:00 UK.
We are pleased to have received many questions from the audience during this live session. Most were answered live however due to time constraints there were some which were not addressed. Our panellists have kindly taken the time to address all questions post-webinar. Please see below a list of all questions received and answers offered by our panellists.
Q: Why do we need to ventilate the solid bulk or bagged cargoes?
A: The primary purpose of ventilation is to minimise the formation of sweat and consequently prevent damage to the cargo. This is achieved either through natural or mechanical ventilation systems.
There are other safety aspects as well, ventilation helps in:
- removing hazardous gases which may be emitted by the cargo,
- preventing excessive heating of the cargo, and
- removing taint.
Q: Should ship owners place further emphasis and training on ventilation, including the completion of detailed ventilation logs?
A: The dry cargo handling courses are usually very generic in nature and do not address the specific hazards associated with various kinds of dry cargoes, whether it be in packaged or in bulk form. Having a focussed training on various aspects of cargo care will assist in making the crew well informed of the specific requirements of handling cargoes and well versed in their understanding of associated risks.
Q: Regarding the 3-degree ventilation rule, does the outside atmosphere have to be 3 degrees lower than the cargo hold temperature or the cargo temperature (if hold is slack). Can the cargo temperature be different than the cargo hold temperature?
A: The decision to ventilate or not should be based on regular and appropriate measurements of the temperature and humidity conditions outside and inside the cargo holds. There are other factors to be considered, like:
- inherent moisture and temperature of the cargo at the time of loading,
- sea temperature,
- relative humidity and
- dew point of the air inside the cargo holds and outside atmosphere.
Master should also consider the instructions contained in the charter party or voyage order. In general, there are two ventilation rules (dew point & three-degree rule) which the master should check and confirm when voyage orders are received.
Dew point rule: Ventilation to be done when the dew point of the outside air is lower than the dew point of the air in the hold. This will put drier air into the hold, forcing out wetter air and reducing the possibility of sweat forming. Dew point readings should be logged.
Three-degree rule: Hygroscopic cargo should be ventilated when the temperature of outside air is at least 3°C below the cargo temperature at the time of loading. This rule avoids the need to take readings in the holds after the voyage has commenced and relies on the fact that the temperature of hygroscopic cargoes, except at their boundaries, changes very slowly during a voyage.
For non-hygroscopic cargoes, like steel, control of moisture in the cargo holds can be achieved by using de-humidifiers.
Q: Should it be mandatory for bulk carriers (not fitted with forced ventilation) carrying expensive water sensitive cargo such as steel cargo to have a de-humidifier?
A: From a cargo care aspect, de-humidifiers are particularly useful when carrying non-hygroscopic cargoes like steel on a warm to cool climate voyage. Ships that are extensively engaged in such voyages may have a de-humidifier fitted, but it is not mandatory under the IMO requirements or Class rules to have these fitted onboard the vessels as the equipment is not critical for safety or environment protection. For ships that are not installed with a de-humidifier, portable units can be fitted in the cargo holds to remove moisture from the hold air and control the dew point.
Q: My ships are regularly engaged in carriage of bagged rice cargo from Thailand and Vietnam to West Africa. What methodology would you recommend for avoiding mold damage to cargo?
Q: For bagged cargoes do we ventilate following the Dew Point rule or Restrict Ventilation?
A: For bagged hygroscopic cargoes, it is recommended to use dunnage to maintain a clear air gap between the cargo and the ship’s side.
Our guide contains detailed guidance on carriage of bagged hygroscopic cargoes, including consideration for the layout and placement of dunnage and other layers to ensure the cargo does not come into contact with water.
It is prudent to consider mechanically ventilated vessels for such trade involving bagged cargoes. If the ship is not fitted with mechanical ventilators, then portable blowers can be considered to create thorough ventilation.
Q: We have seen self-combustion in coal cargoes, which occur at the boundary of fuel tanks. There is no specific requirement in IMSBC code which prohibits heating of fuel tanks. Many ships are also not fitted with tank thermometers. Are there any guidelines on fuel tank heating when carrying coal?
A: Ships that carry heat sensitive cargoes are recommended to devise procedures to minimise the possibility of claims when fuel and fuel residue tanks are heated. Typically, the fuel tanks involved are double bottom tanks adjacent to the cargo holds, and proper planning and bunker management is the best prevention method.
As a part of this process the location of all tanks bordering the cargo holds to which heat may be applied should be identified. The engineers should be advised of the precise nature of the cargo and the proposed stowage plan well in advance of loading so that a suitable fuel oil management strategy can be adopted to minimise the risk of heat damage to the cargo. Possibility of using a low viscosity fuel can be considered when carrying heat sensitive cargoes.
Where possible, heated fuel tanks which do not border the cargo holds should be used, and as far as practicable only the fuel tanks in use should be heated. Maintenance of temperature sensors in bunker tanks should be done periodically and they should always be fully operational and regularly tested. Records of maintenance and tests should be available in the vessel's planned maintenance system.
The IMSBC code schedule for the cargo should be consulted for any requirement regarding stowage in way of heated fuel tanks and engine room bulkheads which are not insulated. Before loading, the tank top temperature above the fuel oil tanks should be measured.
If it is necessary to heat a fuel tank which is in direct contact with the cargo, the oil should be heated to the minimum extent necessary to allow safe transfer. Excessive heating of fuel oil and fuel residues should be avoided. Similarly, hot oil should not be transferred into fuel tanks bordering the cargo holds.
Should the cargo deteriorate on passage due to inherent vice, cargo interests may allege that the damage was caused by excessively hot fuel tanks. Consequently, detailed records of the following are recommended to be maintained by the crew:
- The temperature in the cargo hold.
- Which holds were ventilated and how long for.
- Which fuel oil and bunker tanks were heated and the temperature of the oil they contain.
Q: Soya bean cargoes are prone to caking when the cargo is high in Moisture Content. Ships have to depend on the declaration of the shipper. Is there any way by which ship staff can ascertain that the moisture content of cargo is not higher than the prescribed limit?
A: The carriage of solid bulk cargoes shall be in compliance with the relevant provisions of the International Maritime Solid Bulk Cargoes (IMSBC) Code. However, it is worth noting that the IMSBC code does not cover the carriage of grain in bulk. The specific requirements for the transport of grain are covered by the International Code for the Safe Carriage of Grain in Bulk (International Grain Code, 1991).
As soya beans are oil bearing seeds, it is recommended to obtain a grain and oilseeds quality certificate well in advance of loading in order to ascertain the grade and oil/moisture content of the intended cargo. This would assist with a timely response in cases where the cargo could pose potential issues during the voyage due to its inherent condition.
Soya bean derived products are covered under the IMSBC code as ‘SEED CAKE’. As such, when loading such products, the master should ensure that a cargo declaration form is received, as specified in section 4.2 of the IMSBC code.
Q: How many samples of cargo should be taken (for example of soya beans) to present the real moisture of cargo? for example for 1000mt of cargo. Is there any regulation for it?
A: The sampling procedure for bulk cargoes is mentioned in sections 4.4, 4.6 and 4.7 of the IMSBC code.
The internationally recommended sampling method for oilseeds (like soyabeans) is mentioned under the ISO 542:1990 standards. The club’s publication on carriage of soyabeans refers to the Federation of Oils, Seeds and Fats Associations Ltd (FOSFA) sampling rules.
There are a number of considerations that goes into sampling criteria, but in general the samples must be taken from points distributed evenly and randomly across the entire cargo compartment. Samples shall be representative of the lots from which they are taken. For this purpose, consignment shall be divided into lots, where the lot size determines the minimum number of sampling points, and the collection shall be taken at different levels.
Q: When vessel is advised not to ventilate due to fumigation of cargo holds, who is responsible for the cargo damage due to sweat as vessel moves from one climate to other?
Q: When the fumigator advises to have the vents close for 10 days but during this time as per 3 degree rule the cargo should be ventilated, how we should act?
Q: When Grain Cargo is fumigated, we are asking vessels to issue a LOP for non-ventilation of holds. In case of future cargo claim, will the LOP protect owners from a claim?
A: The ventilation guide (on pages 22 and 23) addresses the issue of scenarios where fumigation requirements may prevent master from ventilating the cargo during the voyage.
Basically, our recommendation is as follows:
- use charterparty terms that specifically tackle the questions of fumigation and ventilation; and it should be agreed that ventilation may not take place during such time with the vessel not being responsible for possible damage to the cargo that may result.
- clauses relating to ventilation, fumigation, etc. needs to be carefully read and understood by the master and responsible officer(s).
- keeping accurate records of when the cargo was under fumigation and when it was ventilated is very important. As is the record of any days when ventilation was not possible, either because of fumigation and / or conditions at sea do not permit ventilation to take place.
Q: Under these COVID conditions, where ship's crew are undertaking fumigation operations. Are we seeing an increased risk of claims? What guidance should be given to ship's crew?
Q: We were recently polishing our procedures and we were working on a fumigation circular for the crews. We ran our draft by the club (entered with Standard as well) and received the following comment: "Based on this plan, approval needs to be obtained from the ship’s Flag State and the relevant Port States and the ultimate decision to undertake this task is up to the Master and crew on board". In this regard, the Flag State's involvement or contribution on the Flag State is not clear to me.
A: The Standard Club is witnessing an increasing number of cases where ships that are typically engaged in carriage of logs are being asked to carry out topping up of fumigation by the crew during the sea passage. Generally, this procedure is supposed to be carried out by a qualified fumigator; however, due to the pandemic and with travel restrictions in place, the fumigators are unable to sail with the vessel.
This is against the IMO guidance contained in circulars MSC.1/Circ.1264 and MSC.1/Circ.1358, which states that the crew should not handle fumigants and requires fumigation to be conducted by qualified operators.
Essentially this means that ship operators and crew, who do not have the necessary expertise to handle toxic materials, are exposed to a new and risky operational environment.
Given the exceptional circumstances and in view of the stated IMO requirements, it is recommended that the ship operator and the fumigation company should develop a plan including:
- How the topping-up operation will be conducted.
- The training that will be given to the crew on the risks involved in handling toxic fumigant materials.
- A risk assessment for the fumigation operation (before proceeding to sea).
- Procedures to mitigate the risks identified.
- Based on this plan, approval needs to be obtained from the ship’s Flag State and the relevant Port States.
Members are recommended to engage with the club to obtain assistance with the letter of indemnity (LOI) against any consequences arising out of this procedure.
The topping-up is generally the same as the procedure followed by the 'qualified operator' during the initial fumigation at the load port. The crew should be aware of which fumigant is used, the information provided in the relevant safety data sheet (MSDS) and its handling requirements. Additionally, they need to be trained on the step-by-step procedure before they conduct the fumigation themselves.
All relevant local regulations and guidelines provided by the authority at the loading port, the fumigation company, IMO circulars MSC.1/Circ.1264 and MSC.1/Circ.1358 should be observed.
The ship should be provided with suitable gas detector tubes for measuring the concentration of toxic fumigant gases; and the fumigation company should always be available to offer any additional guidance if the crew encounter any issues during the operation or subsequent monitoring during the voyage.
Q: A question a bit aside of ventilation, rather on the fumigation and fumigant remains - the fumigant-sleeves. Experienced a case with remains being stored on deck airtight in a drum, which caused an explosion of the fumigant and consequent fire which was extremely hard to put down. Question is how to handle such fire, and how to balance between keeping the fumigant away from water and at the same time open and ventilated container on deck? Same can be serious challenge with loaded vessel and inclement weather.
Q: How to conduct ventilation after log is fumigated in cargo hold? We know some heavy smoking arises when fumigant residue reacts with water.
A: There have been a number of fires and explosions caused either due to the improper application of fumigant material or unsafe disposal of fumigant residues. IMO guidance on fumigation on board ships is contained in MSC Circulars 1264 and 1396 and the IMSBC code.
MSC Circular 1264 mentions specifically that “clear written instructions must be given to the Master of the ship, to the receiver of the cargo and to the authorities at the discharging port as to how any powdery residues are to be disposed of”.
MSC Circular 1396 further highlights that “when phosphine generating formulations are used to fumigate, any collected residue may ignite”. In any case, the disposal of the fumigant waste must be done in accordance with manufacturer’s instructions or with instructions provided by the fumigation company at the port of loading.
Wherever possible, the collection and disposal of fumigation waste should be carried out by properly trained contractors. If residues are to be disposed of by the crew, then disposal of waste should be done in accordance with manufacturer’s instructions, or instructions provided by the fumigation contractors at the load port.
Wastes containing un-reacted material is classed as a hazardous waste and will require special care, and deactivation before disposal. Unless crew members have expertise in determining whether the residue contains un-reacted material, it would be prudent to treat it as though it requires deactivation before disposal, and the manufacturer’s instructions for this procedure should be carefully followed.
Q: In case of hazardous cargoes requiring mechanical ventilation, is there any guidance as to the minimum air change rate/ capacity of the fans? Page 14 has a lot of information regarding specification/construction of fans but not capacity. Obviously latter should be sufficient to maintain hold atmosphere below flammable levels but in most cases a concrete capacity must be agreed before even loading the cargo.
A: As mentioned in page 6 of the guide, for some hazardous cargoes (like ALUMINIUM SILICON POWDER UNCOATED UN 1398, FERROSILICON UN 1408 with 30% or more but less than 90% silicon (including briquettes) and FERROSILICON with at least 25% but less than 30% silicon, or 90% or more silicon), the mechanical ventilation system must have a capacity of at least six air changes per hour based on an empty cargo space for removal of gases and vapours from cargo holds. This requirement is based on SOLAS Regulation II-2/18.104.22.168 and the IMSBC Code schedules for these cargoes.
Q: The club has lot of instructions on ventilation, however does the club have any videos which can be used to train the crew on various cargoes and the practical applications of the 3-degree rules/ dew points and measuring equipment?
A: Thanks for the feedback. The club has been working on a wide variety of loss prevention projects and initiatives. We will include this suggestion for our consideration to work-on in the near future.