Houlder - challenges of tanker ballast installations

Aug 27 2020

Installing ballast water systems on tankers is proving surprisingly tricky. We spoke to maritime engineering firm Houlder about their experiences.

Installing ballast water systems on tankers is proving quite a tricky job, involving careful surveys of the deck, perhaps using laser scanners, and consideration of whether the seawater a tanker will encounter during its lifetime is suitable for the ballast water system chosen.

“There are big sums of money involved that give them no return,” says Ben Myers, project director with maritime engineering company Houlder.

One challenge installing ballast water systems is scheduling the 3D laser scanning, which is done in order to better understand where the new equipment might be fitted.

Laser scanning builds up a 3D computer image of the existing structure, which can be used as a basis for 3D digital design of the new installation.

Doing laser scanning onboard a tanker requires a “hot work permit”. Terminals are reluctant to give permission for scanning when the vessel is at their facilities.

There are explosion proof laser scanners, but “their significant size and weight makes them almost impossible to use in the marine environment,” says Nikolaos Kaloumenos, Senior Marine Engineer at Houlder Limited.

A convenient time to do the scanning is when the vessel has discharged its cargo and is gas free, with engineers sailing on board the vessel. But this all means extra time – since engineers need to stay onboard until they are able to disembark.

The scanning is focussed on areas where the system is intended to be installed, and where the client would like the system to be placed.

It is helpful if the rough location can be agreed by the shipping company and vessel personnel before the scanning starts, Mr Kaloumenos says.


You may need a seawater tank

If an electro chlorination treatment method is used, and the vessel may be sailing in a fresh water environment, then one of the existing tanks will need to be modified to become a seawater storage tank to feed the treatment plant.

This is because the chlorination is made using sodium hypochlorite, generated from the sodium chloride (salt) in sea water. If the ballast water is fresh water, there is no salt present, so a separate supply of seawater is needed.

As a “rule of thumb” this tank should be sized at 1 per cent of the amount of ballast water to be treated, so for example if it is treating 50,000m3 of ballast water, the tank capacity should be 500 m3, Mr Kaloumenos says.

If the water has less than usual saline levels, but contains some salt, you may be able to manage without a tank of salt water, but your system will use much more power.

The fresh water issue could be relevant for tanker operators considering EC systems who nearly always operate in salt water, but do not want to have any constraints in future on where the vessel can trade.


Equipment selection

Making the best choice of equipment is very important. The main choice is between UV and EC systems, and also which supplier you use.

The approach to installation on UV and EC systems is “completely different”, Mr Myers says – particularly because UV needs to be Ex proof).

With EC systems, the system generates hydrogen, as well as the chlorine, which kills the microbes.

In general UV has a greater power consumption, but it depends on how it is operated on the vessel and the capacity.

“Usually – there is a rule of thumb that under 1500 cubic metres per hour, UV is a better choice than EC. Anything on a higher scale, EC would probably be better,” says Mr Kaloumenos.

Many UV manufacturers have tried to make their systems work for larger and larger water volumes, which means a greater power generation capability is required.

“When you start getting bigger than that you get quite a lot of challenges,” he says. “You get a crossover of systems – what’s good and what’s not.”

Houlder has installed a number of UV systems for cruise ships, which are usually smaller capacity than those needed for tankers. EC systems are typically used where there is more water to handle, he says.

You need to consider how much power generation capacity your vessel has and whether that will be enough for what your ballast system will need. But also consider that you will normally be operating the ballast system at times when other services on the vessel are not being used – so there is power generation capacity available.

Some equipment on the market does not yet meet the regulations for any new equipment installed after October 2020. But some companies are offering guarantees that they will be approved in time, Mr Myers says.

“People say, ‘buy our system, we’ll pay any costs incurred.’ They’ve obviously done a lot of homework. I think the client is still in a good place to push that risk onto equipment suppliers. They have invested a lot of time and money over the years.”


Doing it carefully

Mr Myers emphasises the importance of doing the task carefully, with proper engineering work.

Many tanker companies are not carefully considering their options with ballast water, just doing whatever their competitors did, he says.

“There’s a lot of choice in the market, a lot of hearsay, what you can’t beat is good hard engineering facts. The engineering doesn’t lie if you do it correctly.”

“Ballast water has quite a few intricacies, lots of details to get right, which can trip you up. Each vessel is configured differently, spare power, how they operate the vessel.”

“A well planned installation is better than something rushed.”


About Houlder

Houlder is an independent organisation, able to provide “well informed advice” to shipping companies about how to install systems – while shipyards may be inclined to sell whatever they get the best commission on,” Mr Myers says.

It can pay off to “get an independent designer involved early on,” Mr Myers says. “The manufacturer will say yes until they can’t do it. We can do independent feasibility studies early on.”

Sometimes equipment contractors will themselves contract an engineering house to work out how the system should be installed on vessels. But that means you cannot use the expertise of the engineering house to work out which equipment is most suitable.

“You don’t get the 360 degree view of what your options are,” he says.

The company offers design, technical consultancy, analysis and supervision services, with building, modifying and maintaining ships – including work on diving and offshore support vessels, cable layers, Ro-Ro and Ro-Pax ferries,  specialist use vessels and super and mega yachts.

Houlder did a number of projects with tanker operators related to scrubbers, and this has led to projects with ballast water systems.

On the ballast water side, it has done a number of projects in the cruise and ferry sector, which have been installing ballast water systems earlier than tanker companies. But now it is getting more and more enquiries in commercial shipping, particularly tankers.

Houlder’s services range from doing a simple concept feasibility study to a full “turnkey” package including design and installation.

Or it can do all the engineering work up to the design stage, where the shipping company knows exactly what to ask a shipyard to install. Houlder can then support the installation and commissioning work with people onsite at the shipyard.


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