When sampling from the manifold or pipeline, great care should be taken to ensure that the sampling cock through which the product is drawn is absolutely clean. This method of sampling is most difficult and must be carefully supervised to ensure that both shipper and carrier obtain a part of the same representative sample. It is important that when samples are being taken by this method, a constant rate of flow of the product is involved. If there is a variation in the flow rate, the sampling cock must be carefully regulated to ensure that the full sample is taken at a constant rate.
Certain products, such as those reacting dangerously with water and/or air and corrosive liquids or liquefied gases, cannot be sampled by normal means. It may also be dangerous to keep samples of some products for too long as they become unstable.
Labelling of samples
All samples jointly taken should be properly labelled and sealed and identical sets should be kept by all parties. Should shippers refuse to seal the samples jointly, then an appropriate entry should be made in the log book. They should be unilaterally labelled and sealed by the ship’s staff and/or the independent surveyor representing the carrier. The samples themselves must, of course, be identical to those taken together with the shippers and the latter must be notified in writing immediately, to confirm the joint sampling and record their refusal to seal these identical samples jointly with the carrier.
The attention of owners is also drawn to the undesirable practice in many ports of the chief officer being asked to sign paper labels which bear the names of the ship, the shippers, the product, the ship’s tank, the date and place of sampling, a seal number (such as the one to appear later on the wax seal) and the signature of shippers’ inspectors before the loading operations have been completed or sometimes even before they have started. These labels are later attached to the sample containers after they have been filled and closed.
It cannot be too strongly emphasised that the only way to be certain that the proper label is put on the proper sample container is for the ship’s staff to participate in the whole procedure of sampling and sealing and to insist that the sealing and the labelling should take place onboard the ship. All labels should be properly dated and should indicate the local time when they were drawn, name of the product and its destination, the name of the shippers and whether the sample was drawn conjointly with them. The label should also record the quantity, tank number, the tank ullage and
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temperature, the bill of lading and voyage number and whether it is a manifold, pipe line, ‘first run’ or ‘average’ ship’s tank sample after completion of loading. Care must be taken that all these necessary details will remain legible by the use of permanent washable ink. Having signed the labels, the ship is entitled to retain a set of the samples.
Storage of samples
Samples should be stored in a dark, well-ventilated place where daylight cannot enter and away from sources of heat, from living quarters and foodstuff storerooms. Edible oils and chemicals should be stored separately. Samples should be contained in clean, dry and airtight containers, preferably of glass, tinned steel or a plastic material which will not become affected by the contents. They should be closed with corks or suitable plastic stoppers.
A sample log book should be maintained recording the sample number, the sampling date, place, ship’s tank, quantity and kind of product, name of shipper and place of shipment, name of consignee and place of discharge, where stored onboard, and notes on disposal. It is suggested that samples be retained for a period of three months after the ship has discharged.
The carriage of liquid bulk cargoes requires careful sampling as an essential part of the operation. If this is performed in accordance with the procedures set out in this article it will be of considerable assistance in repudiating unjustified claims brought against the ship.
Sampling instruments
Various types of instruments designed to facilitate sampling are obtainable in most major ports. They may be made of glass, stainless steel, aluminium, etc., so that a choice of material is available to ensure that the instrument is compatible with the cargo carried. It is generally advisable to avoid instruments made of copper or copper based alloys.
Sampling instruments should be simple, robust and easy to clean. On the following pages a number of instruments are shown in diagram form together with their descriptions. The Association is grateful to the British Standards Institution for allowing material from B.S.627 to be reproduced.
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