Seed Cake

"Seed Cake" is the term used to describe oil-bearing seeds after the oil has been extracted. Alternative names include "Oil Cake", "Seed Expellers", "Press Cake" and "Meal".

Although all sound relatively harmless, bagged seed cake is listed in the International Maritime Dangerous Goods (IMDG) Code and bulk seed cake appears in the Code of Safe Practice for Solid Bulk Cargoes (BC Code).

The carriage of this product demands special attention as it may self-heat slowly in transit. Seed cake may also ignite spontaneously if it becomes wet, or if it contains an excessive proportion of unoxidised oil.

Furthermore, depending on the oil and moisture content of the cargo, the ship may need to be equipped with facilities for introducing carbon dioxide or inert gas into the holds.

In spite of the recognised risks, there have been incidents in the past, some serious, resulting from seed cake being booked and shipped without full appreciation of the requirements. This Bulletin has been written to re-emphasise the necessary precautions.

Types of seed cake

The most common types of seed cake include those derived from coconut (copra), cottonseed, groundnut (peanut), linseed, maize (hominy chop), niger seed, palm kernel, rape seed, rice bran, soya bean and sunflower seed.

The product is often used in animal or poultry feed. Each variety of seed has a different nutritional property, and blending is carried out to achieve the desired balance.

Seed cake may be shipped as flakes (pods or kernels remaining after extraction) or ground into meal. Both may be compressed to form extruded nuts or pellets, either as an end product or to facilitate transportation.

Products may differ in terms of odour and reactivity with oxygen, but the basic properties of seed cake are broadly similar. However, the applicable IMDG or BC Code requirements vary depending on the oil and moisture content of the cargo.

Extraction

Oil may be extracted from the seeds either mechanically or by applying a solvent such as hexane. Mechanically extracted residues are known as "expellers". Solvent residues are termed "extractions".

Solvents are often used for processing large quantities of seeds. Since solvent extraction produces a greater yield of oil, the residue is usually lower in oil content than mechanically extracted seed cake. However, solvent extractions may emit flammable fumes making it essential that all possible sources of ignition are eliminated.

Spontaneous combustion

Since unoxidised oil is often present in seed cake, exposure to oxygen may produce a reaction which generates heat. Under normal circumstances the rate of oxidation is slow, although the process may accelerate if the material is loaded at an elevated temperature.

Similar behaviour may be caused by microbiological activity. If excessive moisture is also present in the seed cake, self-heating may occur. In extreme cases the combination of a high moisture content and excessive oil residues may result in spontaneous combustion. The risk is magnified if the cargo becomes wet.

Enclosed Spaces

Oxidation may occur during the voyage, depleting the amount of oxygen in the cargo spaces. Carbon dioxide may also be produced. Moreover, harmful fumes may build up inside holds containing solvent extractions if ventilation is less than adequate. Consequently, enclosed space procedures should always be observed when entering a hold, even for routine purposes.

Important

Seed cake is categorised as type (a), (b) or (c) in the IMDG and BC Codes according to the oil and moisture content of the cargo, the method of extraction and the degree of risk. The principal details, which include strict stowage and ventilation requirements, are outlined on the following pages. The vast majority of shipments world-wide fall into categories (b) and (c).

Certificates from the "competent authority" of the country of shipment should accompany the cargo, stating the oil and moisture content of the seed cake. In practice, such certificates are often obtained and supplied by the shipper. Section 22 of the IMDG Code contains the names, addresses and contact details of all designated national competent authorities, and the latest list may be obtained from the Loss Prevention department on request.

It is important to note that the vessel may need to be equipped with facilities for introducing carbon dioxide or inert gas into the holds if the voyage is to exceed five days. Furthermore, solvent extracted seed cake shipped in bulk may be stowed only in mechanically ventilated spaces. Since many dry cargo ships, particularly bulk carriers, are not always fitted with such equipment, operators and charterers should be alert to the precise requirements of the IMDG and BC Codes when fixing cargoes or vessels.

Certain products may qualify for an exemption from the requirements. However, this concession applies only to category (b) and (c) bulk cargoes of "solvent-extracted rape seed meal pellets and soya bean meal", and to category (c) bagged cargoes of "solvent extracted soya bean meal". All other types of seed cake are omitted from the exemption provisions. Furthermore, strict technical conditions regarding the composition of exempted products must be fulfilled. Full details appear in the IMDG and BC Codes, and brief summaries can be found on the following pages. In such instances a certificate from "a person recognised by the competent authority" of the country of shipment (eg an approved superintending company) stating that the provisions of the exemption have been met should be obtained before loading.

It may also be necessary to take regular temperature readings of the cargo at various depths in the hold throughout the voyage. However, the IMDG and BC Codes make no mention of how this is to be achieved, and it is not clear whether thermometers or thermocouples should be used. Similarly, no guidance is given regarding the number and positioning of such devices. The International Maritime Organization (IMO) has stated that responsibility for interpreting the requirements rests with the competent authority of the country of shipment, therefore it is not possible to give definitive advice in this Bulletin.

If the competent authority of the country of shipment is unable to answer queries regarding oil and moisture certificates, exemption criteria, temperature monitoring or "recognised" persons, the local Club Correspondent should be contacted for assistance.

Bulk Cargo - BC Code, Appendix B

To be carried in bulk only with special permission from the competent authority.

Bagged Cargo - IMDG Code, Page 4257

Refuse for shipment any wet, oil stained or damaged bags.

Bags should always be stowed in double strip as shown on page 4236 of the IMDG Code for fishmeal, unstabilised (see Appendix I).

The cargo should be stowed away from pipes and bulkheads which are liable to become heated (eg engine-room bulkhead).

Through and surface ventilation is required.

Smoking and the use of naked lights should be prohibited during loading and unloading and on entry to the hold(s) at any other time.

If the voyage exceeds 5 days, the vessel should be equipped with facilities for introducing carbon dioxide or inert gas into the hold(s).

Regular temperature readings should be taken at varying depths in the hold and recorded. If the temperature of the cargo exceeds 55° C and continues to increase, ventilation to the holds should be restricted. If self-heating continues, then carbon dioxide or inert gas should be introduced.

Common to both

Before shipment the cargo should be properly aged; the duration of ageing required varies with the oil content.

If satisfied as a result of tests that such relaxation is justified, the competent authority may permit seed cakes described in this schedule to be carried under conditions governing SEED CAKE (b).

Certificates from the competent authority should state the oil content and moisture content and should accompany the shipment.

Bulk Cargo - BC Code, Appendix B

The provisions of this appendix should not apply to solvent extracted rape seed meal pellets and soya bean meal containing not more than 4% oil and 15% oil and moisture combined. A certificate from a person recognised by the competent authority of the country of shipment should be provided by the shipper, prior to loading, stating that the provisions for this exemption have been met.

A certificate from a recognised authority should state the oil content and moisture content.

To be stowed in a mechanically ventilated space if solvent extracted.

Electrical fuses in cargo spaces should be extracted. Spark arresting screens should be fitted to ventilators.

Regular temperature readings should be taken at varying depths in the cargo spaces and recorded. If the temperature of the cargo exceeds 55° C and continues to increase, ventilation to the cargo space should be restricted. If self-heating continues, then carbon dioxide or inert gas should be introduced. In the case of solvent extracted seed cakes the use of carbon dioxide should be withheld until fire is apparent to avoid the possibility of ignition of solvent vapours by the generation of static electricity.

Bagged Cargo - IMDG Code, Page 4258

The cargo should be stowed away from pipes and bulkheads which are liable to become heated (eg engine-room bulkhead).

Refuse for shipment wet, oil stained or damaged bags.

If bags are stowed without provision for ventilation to circulate throughout the stow and the voyage exceeds 5 days, regular temperature readings should be taken at varying depths in the hold and recorded.

If satisfied as a result of tests that such relaxation is justified, the competent authority may permit seed cakes described in this schedule to be carried under conditions governing SEED CAKE (UN No.2217 ?IMDG Code Page 4259).

Certificates from the shipper should state oil content and moisture content and should accompany the shipment.

Common to both

The seed cake should be kept dry.

Before shipment the cargo should be properly aged; the duration of ageing required varies with the oil content.

The cargo should be substantially free from flammable solvent.

Smoking and the use of naked lights should be prohibited during loading and unloading and on entry to the cargo space(s) at any other time.

Surface ventilation is required to assist in removing any residual solvent vapour.

If the voyage exceeds 5 days, the vessel should be equipped with facilities for introducing carbon dioxide or inert gas into the holds.

Bulk Cargo - BC Code, Appendix B

The provisions of this appendix should not apply to solvent extracted rape seed meal pellets and soya bean meal containing not more than 1.5% oil and not more than 11% moisture and being substantially free from flammable solvent. A certificate from a person recognised by the competent authority of the country of shipment should be provided by the shipper, prior to loading, stating that the provisions for the exemption are met.

To be stowed in a mechanically ventilated cargo space.

Electrical fuses in cargo spaces should be extracted. Spark arresting screens should be fitted to ventilators.

A certificate from a recognised authority should state the oil content and moisture content.

If the voyage exceeds 5 days, the vessel should be equipped with facilities for introducing carbon dioxide or inert gas into the cargo spaces.

Regular temperature readings should be taken at varying depths in the cargo spaces and recorded. If the temperature of the cargo exceeds 55° C and continues to increase, ventilation to the cargo space should be restricted. If self-heating continues, then carbon dioxide or inert gas should be introduced. The use of carbon dioxide should be withheld until fire is apparent to avoid the possibility of ignition of solvent vapours by the generation of static electricity

Bagged Cargo - IMDG Code, Page 4259

The provisions of this Code should not apply to a consignment of solvent-extracted soya bean meal containing not more than 1.5% oil and 11% moisture, being substantially free from flammable solvent, which is accompanied by a certificate from the shipper stating that the substance, as offered for shipment, meets these requirements.

The cargo should be stowed away from pipes and bulkheads which are liable to become heated (eg engine-room bulkhead).

Common to both

The seed cake should be kept dry.

The seed cake should be substantially free from flammable solvent.

Surface ventilation is required to assist in removing any residual solvent vapour.

Smoking and the use of naked lights should be prohibited during loading and unloading and on entry to the cargo space(s) at any other time.

Further recommendations

In addition to the regulatory requirements, further action may be taken to minimise the risks;

Prior to arrival

Holds and bilges should be clean and free from odour. If sea water is used for cleaning, rinse with fresh water afterwards. The holds should be completely dry before loading and bilge lines should be tested.

Holds should be inspected for signs of infestation, particularly after carrying agricultural products. If so, fumigation may be required prior to loading.

Check that all ventilation arrangements (eg fans, trunkings, dampers, seals) are functioning correctly.

Verify that the hatchcovers and hold access doors and lids are watertight.

Test and check the equipment for introducing carbon dioxide or inert gas into the holds.

Ensure that suitable apparatus for measuring humidity and dew point levels within the holds is available on board and operating correctly.

Remind crew members to be alert to the possibility of solvent fumes and/or oxygen depletion if it is necessary to enter the holds, and to observe enclosed space procedures.

Make an appropriate entry in the deck logbook once all pre-arrival checks have been carried out.

In port

If an exempted cargo, before loading obtain copies of the certificates stating that the provisions for the exemption have been met.

If not an exempted cargo, obtain copies of the certificates stating the oil and moisture content of the cargo and follow the applicable IMDG or BC

Ascertain whether hold and/or cargo fumigation will be required.

If ventilation routines are likely to be affected by fumigation in transit, a written protest should be lodged with the shippers.

Establish how the cargo quantity will be determined on completion of loading. If by draft survey, ensure that a deck officer accompanies the attending surveyor to agree and record all figures on behalf of the ship.

Inspect the cargo ashore prior to loading and reject all bags found to be torn, stained or damp, including any with a musty or rotten odour. If the shippers or charterers maintain that such a smell is normal, cargo documents should be claused accordingly. In the event of a dispute, the local Club Correspondent should be notified immediately.

If rain is likely, ensure that the hatchcovers can be closed at short notice. Alternatively, hatch tents or similar arrangements should be available for immediate use.

If possible, temperatures of the cargo should be obtained prior to loading. For bulk seed cake, a probe thermometer should be inserted to a depth of at least 1 metre below the surface, although an ordinary thermometer may be used if the seed cake is freshly exposed. If the temperature of the cargo is found to be substantially above the maximum air temperature, loading should not proceed and the local Club Correspondent should be contacted for assistance.

Clausing of the Bills of Lading may be required depending on the information appearing on the cargo certificate and the description of the cargo furnished by the shipper. If any doubt exists regarding the condition, quality or oil and moisture content of the seed cake, the Managers should be contacted for advice.

In the event of other difficulties, or if the ship is unable to observe the applicable IMDG or BC Code requirements, the local Club Correspondent should be contacted immediately.

On passage

If it is necessary to enter the holds to measure humidity and dewpoint levels, or for any other reason, ensure that enclosed space procedures are followed.

Strict attention should be paid to the ventilation requirements stipulated in the relevant sections of the IMDG or BC Code. All details concerning ventilation on passage should be entered in the deck logbook.

Normal precautions to minimise the possibility of sweat should be observed. Humidity levels within each compartment together with the associated dew point temperatures should be measured at least once a day, provided it is safe to do so. All details should be entered in the vessel deck logbook. Seawater temperatures should also be recorded if climate changes are anticipated.

If prudent ventilation measures fail to prevent the development of mould or the onset of heavy sweat, the local Club Correspondent at the discharge port should be notified so that a survey can be arranged on arrival.