BWMS: Why bulkers are different

APRIL 25, 2017 — The U.S. dry bulk market will face a shortfall of vessels in a few years of time unless owners of this type of vessel can persuade the U.S. Coast Guard that bulkers face a number of specific difficulties in implementing the requirements of Ballast Water Management (BWM) regulations. That is one of the many points to emerge from a discussion paper just published by INTERCARGO (The International Association of Dry Cargo Shipowners).

INTERCARGO says it that it should be recognized that BWM implementation in a newbuilding vessel case is totally different than retrofitting an existing vessel, while a bulker is also a different case than other types of ships.

Aside from the issue of the availability of U.S. Type Approved systems, INTERCARGO argues that the availability of IMO Type Approved systems is insufficient. Though there are currently 69 Ballast Water Management Systems (BWMS) that have been Type Approved by their respective administrations.this does not mean that a ship owner or shipyard has a choice of 69 different systems.

From a newbuilding perspective, not all the systems are suitable as a number of them are not able to treat the water at the rate required by the ship's ballast system to enable normal ballasting operations. Compared to most other vessel types, bulk carriers together with tankers and gas carriers tend to have a larger ballast capacity with pumps of higher capacity.

Retrofitting existing fleet poses even greater challenges than those faced by newbuilds, due to the size limitations imposed by available space and additional electrical powering requirements imposed by these systems compared to the available power onboard.

Another issue is posed by the fact that a significant portion of the world bulker fleet utilizes the highly energy efficient gravity discharge system for the topside ballast water tanks unique to bulk carriers. On vessels using this system, the top side tanks are typically filled from the fire main, not from the ballast line and are discharged directly overboard, which of course is incompatible with the requirements for the obligatory discharge monitoring and secondary discharge treatment required to reach the performance standard or for neutralization of any chemicals used in the treatment process.

UV Systems generally require a secondary treatment phase at discharge to achieve the required D-2 standard and thus to fit this type of system on bulk carriers with gravity discharged top side tanks is extremely challenging because of the technical obstacles and financial burden associated with altering the existing arrangements onboard a vessel.

It is not possible to simply connect the top side tanks to the double bottom tanks as the structure of the lower tanks, particularly the hopper tanks, is not able to support the rise of pressure due to the additional head of water without additional strengthening of the tanks. It has been estimated that the additional weight, in the form of stiffeners, collar plates and brackets, would amount to between 50 and 200 tonnes depending on the vessel size. The considerable modifications, damage to and the repair of the ballast tank coatings also increases the scope of work that will need to be carried out.

Connecting the top side tanks to each other, via a valve, and then piping back to the engine room brings its own problems such as penetrating the engine room forward bulkhead and running ballast piping through fuel tanks. There will also be problems with effective emptying of tanks due to trim, which may lead to operational difficulties during loading and unloading.

A third possibility is to connect each top side tank to the ballast main in the double bottom/duct keel. In addition to modifications to existing pipework, fitting of pipe supports, new penetrations through watertight boundaries and repairs to the existing ballast tank coating system, isolating valves would need to be fitted to each new branch of the ballast line.

Fitting a common ballast discharge line through the top side tanks with cross valves to each tank is an option; however this would also lead to major modifications including penetrations through the Engine Room bulkhead, other tight bulkheads, fitting of pipe supports and damage to the ballast tank coatings.

On top of the difficulties associated with the discharge, gravity discharged top side tanks are not filled by the ballast line serviced by the ballast pump but are filled using the fire main and general service pump. Therefore, a second treatment system would be required to treat the uptake of the general service pump, either that or a major modification to the fire main so that ballast water entering the fire main is passed through the ballast water treatment system.

Most chemical treatment systems require monitoring of the discharge and then a chemical neutralization phase and with these systems the same challenges faced with fitting a UV System would also apply. There are, however a limited number of chemical treatment systems which treat on the uptake only but modifications would need to be carried out.

In addition to the major modifications that would be required, the advantages of gravity discharged tanks would be lost, these advantages include; a) Faster ballasting and de-ballasting; b) Less electrical energy used; c) Less wear and tear on the existing pumps and piping; and d) Effective tank stripping.

Working around the problems of gravity discharged top side tanks is only one of the problems discussed in the INTERCARGO paper — including those related to meeting the requirements of U.S. regulations.

USCG GAME CHANGER

INTERCARGO says that the December 16 granting of U.S. Coast Guard Type Approval to three BWMS has resulted in a "game changer" in the Coast Guard's extension process as shipowners will now have to document and justify how they cannot possibly fit an approved system on their ship.

For future extension requests supporting documentation providing such information as the evaluation of BWMS and discussions with BWMS vendors, issues with the availability of suitable systems, lack of drydocking space, problems encountered during purchasing, installation and commissioning, and a systems operational practicality pertinent to the individual ship and or trade, as relevant, will be required to gain acceptance. The only recently understood unique and onerous demands of ballast water treatment system requirements for bulk carriers may prove helpful when requesting USCG future extensions, in comparison with other ship types that require a much smaller and simpler system.

"Otherwise," says INTERCARGO, "the U.S. dry bulk market will be facing a shortfall of vessels in a few years of time, in the case where there will not be enough dry bulkers compliant with U.S. legislation. Who is going to meet the trade demands of the United States?"

INTERCARGO notes that "fortunately both the US Coast Guard and EPA to date have been found to be realistic in the implementation of the existing and in force ballast water regulations and it is hoped that this pragmatism will continue when viewing extension applications for bulk carriers with the many very real challenges bulk carrier owners face; an honest appraisal and documentation of the difficulties faced will be necessary together with a reasoned assessment of the possibilities for fitting the U.S. type approved equipment that may be available."

Download the INTERCARGO paper HERE

 

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