For example, on a typical chemical tanker with deep-well pumps and above deck lines, the tanks forward of the manifold, when the vessel is trimmed by the stern will have to drain its lines back to the manifold. Complex pipeline configurations, which most tankers have, often result in sections of pipe that will not drain due to the creation of a vacuum within the pipe. Opening all valves and drain points, not just those at the lowest point, helps to break any vacuum within the piping system and allows the pipe contents to drain.
3.4.1 Contract Review/Order Confirmation
3.4 Pipeline Contents and First-Foot Samples It is common to receive a nomination to inspect a loading where the inspection costs are to be split 50/50 with the buyer and the seller. In some instances, the job instructions only come from one of the parties; usually the seller. In this situation, the interests of the seller and the buyer, with respect to the level of inspection required and the amount of risk they are willing to assume, are frequently not the same. On chemical and most petroleum shipments, a first- foot sample is normally taken to identify any undetected contaminants in the shore or vessel pipelines; and, if any are detected, they will not, subsequently, contaminate the entire cargo. If the buyer is also the charterer and the instructions are coming from the seller, the seller may not feel that a first foot sample is needed as they are selling based upon shore tank analysis. The buyer on the other hand may be assuming that first foot samples are being taken, and in the event of a cargo dispute, will expect us to be able to produce first foot samples. When faced with this situation, we must act to protect our client’s and our own interests.
In these scenarios we must advise all parties to the transaction that we have not been instructed to take first-foot samples and that this is something that we do not recommend. Language such as the following should be sent to the clients as part of the Order Confirmation: According to our instructions, first-foot samples have not been requested. Due to the risk of cargo contamination from non-determinable line quantities, we recommend first-foot sampling and testing.
3.4.3 Conclusion
3.4.2 Vessel Pipeline
The possibility of cargo contamination when inspecting shipments is always of paramount consideration, and especially when dealing with chemical cargoes, as it frequently takes only a very small amount of contaminant to put a cargo off- specification. Pipelines, especially the vessel’s pipelines, represent an area where potential contaminates from previous cargoes or tank washing material can go undetected due to the very limited access available for inspection. The taking and analysis of first-foot samples helps determine whether or not undetectable contaminants were present in the pipeline. Whenever we are instructed not to take first-foot samples, we should:
The issue of pipeline contents has always been problematical because they are rarely 100% accessible. However, it is important that all pipelines that are empty prior to transfer be checked, as far as possible, by requiring the vessel to open all cargo valves from the manifold to the tank and to open all of its drain valves. This operation should be observed by the attending SGS Inspector. This is especially important when the vessel’s lines have not been blown back to the tank with air or inert gas.
It is important to identify and record which manifold, tank, or drain valves were opened.
There may be cases when draining a vessel’s lines back to the tank is not possible.
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