I was lecturing a month or so ago when a delegate asked me what Line Displacement was. I said it was a procedure that the cargo inspector carried out to check the shore line content before and after loading. It occurred to me that I didn’t really know what happened during this procedure, but I got a chance to find out a few weeks later when I bumped into my former boss, Tony Yates who is Head of Operations at BP Oil International in London. Tony has a wealth of experience; he has served at sea with BP and was at one time with an inspection company in the USA.
This explanation is how I remember the conversation we had:
Before bulk loading or discharging of a tanker is started the inspector will want to carry out the line displacement procedure in order to ensure the pipeline contents are the same before and after the operation so that no-one is disadvantaged when shore tank measurements are used for Bill of Lading and Outturn determination. It is usually expected that pipelines are full before and after. In order to verify this a small portion of the cargo is loaded or discharged and this is usually equal to or slightly more than the calculated line volume between the ship and the shore tanks. Let’s say it is 400mt in this example. Cargo operations will be stopped while the inspector measures what has been loaded/discharged to/from the shore tank and he will compare this with what has been discharged/loaded from/to the vessel. If both the ship and shore figures agree that 400MT has been transferred then the line is confirmed as full. As measurement is an art and not a science then a small degree of tolerance will be permitted between the two sets of figures, although this often leads to a degree of debate as to what is acceptable tolerance or otherwise!
This procedure should not take long, obviously it depends on the length of the shore line and how much cargo it holds, but the whole procedure should not delay commencement of bulk cargo operations by more than an hour at the very maximum.
What are the laytime and demurrage implications for this time? I would argue that this is all part of the loading/discharging procedure and it is in both ship and shore interest to ensure that the quantities are as accurate as possible. The same applies to buyers and sellers under an oil contract and unless there is anything specifically mentioned to exclude this time, then time must continue to run for laytime and demurrage purposes.
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9 thoughts on “Line Displacement – an Explanation”
Phil, that is a helpful explanation and I agree with your analysis re Laytime/Demurrage, this is part of the loading/discharging operation. In a wider sense it is also important as a failure to perform a line displacement does open up arguments over the veracity of shore figures in the defence of any cargo shortage claim.
Stephen
Hi Stephen
Thanks for your comment. You make a very valid point and I thank you for highlighting a potential pitfall
best regards
Phil
Gday Phil,
Given the value of oil these days in my experience line displacements aren’t used tha often to prove a full line as companies prefer more sophisticated methods through meters etc. it’s not saying they don’t happen for this reason however I would suggest its more to leave a line resting on a specific product or on water in the event of sabotage or for safety reasons. Some SBM will want the ship to discharge as a last product a slug of seawater to have the line resting on this in case some fisherman hooks the line for example.
However I would agree that it’s part of the loading / discharge process.
Good luck
Toby
Thanks Toby
You are right there are other ways to determine this but I'm no expert and will not offer to explain them!
Best regards
Phil
Thanks, Phil – Quite clear !
Thanks Eleonora,
I'm glad you found it useful
best regards
Phil
Hi Phil,
You may remember me from Marine Cargo Experts as Oil Loss Control specialists. Tony is right in his description. This procedure is one of the most important of many procedures during a custody transfer operation and for cargo reconciliation. Many Terminals have a variety of differing methods of determining line fullness. There is a "Line press operation" (using a shore pump to press up the shore line), line circulation (tank to tank via the shore manifold or offshore manifold) and line displacement procedure. There should be an 'agreed tolerance' at the various Terminals that do perform this latter operation but often there is no guidance but a rule of thumb has been used at many Terminals of 2% of the line volume + or -. When there is a large discrepancy then delays can ensue. One has to redo the line displacement and assuming differences are then reconciled the claim of shortage has to be put on either the Terminal or ship system. Some Terminals which have 'over the hill' line configuration where it is known there will be a large discrepancy, do give a credit against the Outturn for the any ship/shore difference determined following line displacement. Unfortunately one of the weaknesses over the years has been the lack of accuracy in estimating ships line slackness prior to the operation. The API are bringing out a new Line Fullness document which goes through in detail how each of the procedures should be performed properly. There is a recommendation to press up the ships lines to the manifold prior to performing the Line Displacement operation and prior to the measuring of the ships tank quantity,This does reduce the level of uncertainity as experienced by us in at least one Terminal MCE have attended. Hope this helps.
Malcolm Maunder – Cargo-training@hotmail.co.uk
I am now a consultant doing Training covering Oil Loss Control, oil shortages & contamination claims prevention and also in a support role for MCE covering Commercial & training.
Hi Malcolm
Of course I remember you! Thanks for your comments and your very useful explanation – this is a very popular post and I think readers will find this additional information very helpful.
best regards
Phil
Effective claims handling is all about seeking to find justified reasons for reducing claim quantum. Unjustified reasons may result in further reductions, but are likely to spawn not only the risk of upsetting relations but inviting the prospect of any advatntage being clawed back by e.g. freight increase on the next voyage, or simply finding the owner less interested for further business.
An often good means of scoring points is in a mental check of the number of days in particular month.
David Mount