By Richard Smith, Senior Vice President, Certispec Group of Companies
A trip to the grocery store to pick up some staples for the pantry like rice, flour, peas or cornflakes is made much easier by the fact that the weight and quality of what you will be buying is marked on the packaging. We pay for our goods at the checkout and travel home knowing how much we purchased and its ingredients.
Imagine the same type of scenario when a buyer in Japan decides to purchase thousands of tonnes of metallurgical coal from a supplier in Canada. No simple trip to the local store where the coal has been pre-packaged and conveniently marked with its weight and list of ingredients. Now we are looking at a ship loading the coal, in bulk, transiting the Pacific Ocean and delivering it to a port in Japan.
Though the buyer has undoubtedly already indicated to the supplier in Canada just how much coal he wants and the quality he needs for his purposes, it is a deal being made between parties a half world apart and, in some instances, who have never met or transacted business before. So how does the buyer know for sure what he is buying and how much he is getting? No simple pass across a scanner at the checkout for this purchase that will involve millions of dollars.
Every year, millions of tonnes of commodities such as coal, grain, sulphur, potash, wood chips, petrochemicals, petroleum crude and refined petroleum products are loaded onto ships and exported through the Port of Vancouver to buyers around the globe. In 2017, over 37 million tonnes of coal, 23 million tonnes of wheat and other crops, 7 million tonnes of potash, 2.5 million tonnes of sulphur and 1.8 million tonnes of crude oil moved out of the Port to international markets where buyers were looking for confirmation of the quality and quantity of the goods they had purchased.
Enter independent cargo surveyors, samplers and testers — trained individuals who use industry and internationally accepted standards and operating procedures to verify and certify both the quality and the quantity of commodities loaded to deep-sea vessels.
Although they may be hired exclusively on behalf of any interested party involved in the transaction (underwriters, financiers, etc.) cargo surveyors generally act jointly on behalf of the buyer and the seller to produce certificates of weight and quality that will be binding on those parties. In such instances, they are advised by those parties of their contractual requirements with respect to weight and quality for the commodity to be inspected and will perform sampling, testing and weighing accordingly.
These requirements usually specify the agreed-upon conditions and standards under which the quality and quantity determination will be undertaken and may include reference to specific standards produced by industry and/or internationally recognized standards from organizations such as ISO (International Organization for Standardization), ASTM International (American Society for Testing and Materials), FOSFA (Federation of Oils, Seeds and Fats Association), GAFTA (Grain and Feed Trade Association) and API (American Petroleum Institute).
It goes without saying that any laboratory analysis performed on a cargo made up of thousands of tonnes of a product, particularly one like coal that is non-homogeneous, needs to be performed on a sample that is truly representative of that massive tonnage, particularly when you remember that the sample amounts involved in much of that analysis will be measured in grams or millilitres. Try to imagine a cargo of a half million barrels (about 80 million litres) of crude oil being represented in tests that will be performed on just one or two litres of sample or a cargo of 250,000 tonnes of coal (250 million kilograms) being represented by just a few kilograms.
For this reason, the collection and preparation of samples needs to be very strictly controlled and monitored to ensure that a truly representative sample is provided to the laboratory. It is crucial to the entire loading process.
Internationally recognized organizations such as ASTM International produce standard methods for sampling and testing that have become universally adopted by parties involved in the maritime transportation of commodities like coal, petroleum and petrochemicals. Other industry driven organizations — for example, FOSFA and GAFTA — have produced similar standards for commodities such as wheat, grains and vegetable oils.
For most bulk cargoes that are being loaded to ships, these products are transported great distances from their points of origin. Most often, this is accomplished using rail transportation and, in the case of crude oil and refined products, also involves the use of the Trans Mountain Pipeline. Products are eventually delivered into stockpiles or storage tanks at terminals in the port and then loaded via conveyors or pipelines onto the ships.
Although sampling may take place at any place within this transportation chain, for a variety of reasons it is most usual that samples taken for the purpose of certifying the quality of a product are taken during, or immediately before, the actual ship loading. This normally occurs at a point physically located between the shore-side stockpile and the ship (as close to the ship’s rail as possible). In the case of solid cargoes, this will involve taking a sampling from a moving conveyor belt and for liquids this will mean sampling a storage tank or a flowing stream from within the pipeline connecting the storage tank to the ship.
Although sampling of the stockpiles themselves is undertaken, it is quite a complex operation involving a great deal of planning and preparation and is quite labour intensive due to the hazards involved in working on and around the pile. In terms of obtaining a truly representative sample of a cargo loaded to a ship, it is considered to be less effective than sampling off a belt throughout loading.
In some specific circumstances however, sampling from a stockpile may be required prior to the ship loading. For instance, the surveyor may be requested to take samples of solid cargoes for the determination of the Flow Moisture Point (FMP). The FMP is the point at which a granular bulk material becomes fluid and it is used to calculate the Transportable Moisture Level (TML) — the maximum moisture content for a solid bulk cargo. Transportable Moisture Levels are used by Transport Canada and shippers to evaluate if a cargo’s moisture content makes it safe for shipping. In this case, the results of such tests are best determined before loading starts.
Sampling can be undertaken by manual or automatic means. In either case, a recognized methodology will be used, as mentioned above, to collect the samples and to prepare them for testing. Incremental samples will be taken throughout the loading which, on completion of loading will be combined and used to create a gross sample (representative of all cargo sources loaded to specific parcels or the load in total).
Based on the type of commodity, the total mass of the cargo to be loaded and perhaps some other commodity-specific properties such as granularity or moisture, the sampling methodology used will specify the amount of sample to be taken, the number and mass of sample increments to be taken throughout the load (based on loading rate and total mass), the cargo source (railcars, stockpiles, storage tanks), individual cargo parcel volumes and the manner in which the gross sample, collected during the cargo transfer, needs to be prepared prior to being sent to the laboratory for testing.
Regardless of the method by which the sample is extracted, it must be ensured that a completely representative sample is taken from the complete cross section of the cargo flowing along a belt, in the case of a solid, or from within the liquid flowing through a pipe. A sample scooped from the surface of cargo flowing across a belt may well include too great an amount of fine cargo particles to be representative of the cargo as a whole.
Manual sampling from a moving conveyor basically involves using a scoop of a pre-determined size to retrieve a sample off the belt at pre-determined intervals (usually about every three to five minutes) throughout the transfer to the ship. As mentioned above, the technique used by the sampler ensures that the scoop of sample taken is from across the entire cross-section of the product on the belt. These incremental samples (each about 700 g) are collected in a plastic bag and each bag will contain up to about 10 kg of product before being changed for another bag. These bags are all carefully marked with relevant data such as cargo type and grade, cargo source, cargo destination, and the amount of cargo the sample represents (the number of railcars or the weight of the cargo), etc.
On completion of the loading, these bags of incremental samples are used to make a “gross” or “composite” sample that is representative of the entire cargo loaded to the ship. The amounts of each incremental sample to be used in the gross sample are based upon the percentage of the total cargo weight that each increment represents in this gross sample. The gross sample must be thoroughly mixed and then split using a process called “riffling” to produce several identical samples, representing the cargo loaded. These individual samples will then be sealed and distributed to several different parties including the testing laboratory where the quality certificate will be issued.
Although the manner in which the physical samples are taken, in the case of a liquid cargo, may differ to those described above, the basic process is very similar in that there will be a number of incremental samples taken prior to or during the loading that will be made into a composite sample and will represent the cargo as a whole.
One major difference between solid and liquid cargoes, in the case of manual sampling, is that normal industry practice involves taking samples from the shore storage tanks to be used to supply the product for the load prior to the commencement of the load rather than from the product flow in the pipeline during the cargo transfer. This is not the case when automatic, in-line samplers are used.
Samples are usually taken from the top of the storage tanks via a hatch in the roof of the tank using sample “thiefs” that are lowered into the liquid by the sampler and used to collect representative samples from different levels/layers, ensuring that any layering of product is taken into account (stratification of liquid products due to differences in temperature, viscosity and density are very common). These representative samples are then blended in the laboratory to produce a “composite” sample that will be used for laboratory testing and delivery to any other interested party or sealed for retention.
In the case of liquid samples, brown glass bottles and/or specially lined cans are used to take and store samples to protect the product from ultraviolet light and possible contamination due to contact with the interior surface of the sample container. For samples of Liquefied Petroleum or Liquefied Natural Gases (LPG, LNG), specially constructed stainless-steel sample cylinders (or “bombs”) are used to take samples.
Automation of processes in cargo handling is constantly evolving and cargo sampling is no exception.
As the price of commodities continues to rise and buyers demand higher quality, the need to provide fast and accurate certification grows. As a result, the need to provide truly representative samples in an efficient and safe manner has produced a wide variety of automated mechanical sampling systems.
For solid cargoes such as coal, these systems can be extremely complex, involving multi-million dollar plants that will not only take the incremental samples but also do part of the sample prep work by crushing and riffling the samples during the loading operation.
Automation for liquid cargoes involves a completely closed, computer-operated system that retrieves incremental samples of the product flowing through the pipeline based on the amount of cargo to be loaded and the flow rate on its way to the ship. These incremental samples are collected in a stainless-steel container which is checked for cleanliness by the sample technician prior to being installed into the system and then retrieved by the technician on completion of loading.
The sealed container is then connected to a mixer which will thoroughly mix the contents to ensure a homogeneous blend of the product prior to testing and splitting for distribution and retention.
There is no doubt that, from a safety perspective, automation of the sampling process has improved matters greatly. The process no longer involves having someone leaning towards a moving conveyor belt and sticking a long-handled scoop into the cargo flow (in the case of bulk solid cargoes) or climbing storage tanks and having to handle hazardous products (in the case of petroleum and petrochemicals). However, experience shows that these automated systems require constant attendance and maintenance by qualified sampling technicians to ensure proper operation and, in this regard, the training and capabilities of sample technicians may have changed but their basic role in this very important aspect of the export process has not. Indeed, they are often required to quickly switch back to manual sampling techniques if the automated systems refuse to work properly.
Samples are usually sealed and retained by the surveying company for a period lasting normally 30 to 90 days following the loading in case there are any disputes. Thereafter, they are disposed of by returning them to stockpiles or storage tanks.
Richard Smith is the Senior VP for the Certispec Group of Companies which offers marine surveying, inspection, sampling and laboratory testing services across Canada, the USA, Caribbean and Africa. Surveyors, samplers and laboratory technicians from Certispec Services sample, test and certify quality and quantity on cargoes of coal, sulphur, potash, ores, petrochemicals, petroleum crude/refined products and vegetable oils being shipped out of the Ports of Vancouver and Prince Rupert on a daily basis.