A debate on wall washing of chemical tankers


Published: 17 November 2014

Cargo contamination claims are one of the key risks the Association deals with when assisting members in the chemical tanker trade. Ensuring tanks are actually at the right level of cleanliness prior to loading is key, but it is open for debate whether exisitng testing methods are sufficient to verify the same.

The Association is grateful to Guy Johnson, Director of L&I Maritime for contributing to this debate.

The situation

Cargo contamination claims are one of the most frequent issues the Association has to deal with for chemical tanker members, a related and equally frequent issue are disputes over the cleanliness of tanks on a vessel prior to loading.

Both types of disputes come with the risk of significant claims and losses, and given the very technical nature of the subject matter it is likely that only through extensive scientific investigation it is possible to come to a view as to what the precise underlying issue may be.

That means there will inevitably be significant costs and time involved in the investigation, analysis and debate over the evidence.

One particular feature in these disputes is the methodology by which a vessel's tanks are tested for cleanliness.

A common method is the wall wash inspection which means that part of the cargo tanks are "washed" with a solvent which is then analysed to see what - if any - materials can be found therein, i.e.: to check against the presence of possible contaminants in the tanks.

Over time this method developed from a somewhat straight forward process, intended to demonstrate the ability to clean tanks to a certain standard, and it has now evolved into a very exacting testing regime that may be looking to check for the presence of materials in the parts per million.

Whether wall washing is an effective means of checking the cleanliness of tanks, and whether it remains suitable and appropriate or whether there are acceptable alternatives is a matter of debate. A debate, however, that will have real monetary significance to shipowners and charterers.

In the attached article, Guy Johnson from L&I Maritime discusses the issues concerning tank cleaning, wall washing and proposes an alternative methodology.

While there is no doubt ample room for an intense debate on this issue, given the continued significance and frequency of tank cleanliness disputes and cargo contaminations disputes in the chemical tanker trade, it is debate worth having.

Indeed the Association expects that as standards for shipments may increase, not least under pressure from the cargo side, both shipowners and charterers should be prepared for more disputes of this kind in the future.

Loss prevention advice

The Association believes that good loss prevention in this area requires a very in depth understanding of the particular nature and challenges that one encounters when operating chemical tankers.

Tankers may have tanks made of different materials or coated with different types of coating.

Assuming, for present purposes, that the tanks are well constructed, and maintained, and that any coating is of good quality and properly applied, one must then turn to an understanding of how these react with different cargoes.

At this point one will have to delve into a scientific level of investigation as it is a known issue that a particular tank material and / or coating may react with a particular cargo in one way and quite differently with another cargo. This is because of the fact that the cargoes carried by chemical tankers are - typically - chemically reactive and indeed cargo may end up being absorbed into the coating of a tank which can presents serious issues and challenges.

Hence one needs to understand in advance both the vessel / her tanks and the cargo or cargoes for the carriage of which the vessel is to be employed. Additionally one needs to factor in the nature of the previous cargoes carried, and the system as well as procedure for cleaning the tanks between laden voyages.

In other words, operating chemical tankers means having to operate at an advanced level of sophistication which is challenging and requires a high level of knowledge and experience.

Owners that are experiencing repeat issues with tank cleanliness disputes and / or cargo contamination disputes would be well advised to adopt a "back to basics" approach that starts with a close look at the vessel, her present condition, the experience of the crew, the particular types of tanks / coating on board, her cargo experience, as well as the on board systems and procedures for the cleaning of the tanks.

Beyond such an introspective view, it will be necessary to consider the suitability of the vessel for particular cargo trades, the likely demands and standards which cargo and charterers may seek to impose on the vessel, as well as the terms on which the vessel will be performing her cargo voyages (i.e.: charterparty and bill of lading provisions).

Armed with a complete picture, an owner or operator should be in a position to make well informed choices that will assist in managing the risks involved.

The Association will always be ready to assist members in analysing a particular situation and work towards finding solutions that help members carry out their trade in a safe and successfully risk managed way. For specific claim issues, members are asked to contact their usual Skuld Business unit.