Reach for the skies

Higher and further crane outreach is a necessity not a luxury as Alex Hughes explains

There is no getting away from it: container vessels and quayside gantry cranes are getting ever larger as both shipping lines and terminal operators seek new ways to boost productivity.

While port authorities are having to invest in deeper draft facilities in order to continue to attract these larger vessels, terminal operators find themselves in something of a quandary: should they buy new cranes to handle these large ships, or upgrade existing equipment? More and more are taking the latter option.

But it is not for the faint-hearted. Last year, Angelo de Jong, procurement manager at Khalifa Port Container Terminal, told Port Strategy that heightening cranes and increasing their outreach is a costly operation – and one to be avoided if at all possible.

Yet still terminals continue to do this. Medcenter, for example, increased the outreach on nine of its ZPMC gantries to enable them to handle 23 rows of shipped-stowed containers, while Paceco España has been raising the height of three gantry cranes operated by Noatum at Valencia to 42 metres.

Specialist help 

While to some extent all crane manufacturers are undertaking this work, Kalmar has become something of a specialist, heightening or extending booms on nearly 100 ship-to-shore cranes globally. The most recent projects - all contracts involving three cranes - were for DP World, in Antwerp; PTP in Malaysia; and TCB, in Barcelona.

“We are happy to undertake crane heightening on both our own cranes and also on those manufactured by third parties,” says Mikko Vuojolainen, vice president, crane upgrades. “Of the most recent projects, the cranes in Antwerp were supplied by us, while those in Barcelona and Malaysia were built by other manufacturers.”

STS crane heightening and boom extension projects, he notes, are inextricably linked to a need by a terminal to increase the maximum size of vessel that it can serve.

“The decision to upgrade STS cranes immediately sets the course for the future of the terminal and the type of customers it can attract. So, it is not simply a case of return on investment. Instead, the investment decision is a strategic choice: one in which a terminal can either opt or not to serve larger vessels.”

Some terminal operators, he says, do take a gamble, undertaking crane heightening and extension without first securing customers with vessels to serve.

“If that gamble pays off, it gives them a competitive edge over neighbouring terminals, because they are already set up to handle these larger vessels,” says Mr Vuojolainen.

But there are also a number of terminal operators who first secure larger vessels and only then go in for crane heightening. However, these are invariably put under pressure to get everything ready on time, or face lost revenue.

Outreaching 

Mr Vuojolainen says that Kalmar has completed several projects which have not only involved heightening, but also an increase to the outreach. The decision to do this, he says, depends on the type of vessel calls. However, while heightening is relatively straightforward, extending the crane boom can be more challenging.

The average heightening range requested by clients tends to be between four and ten metres. But it is not simply a case of making the cranes higher. Maintaining or even improving the original crane stability, strength and stiffness all have to be taken into consideration and work can therefore include additional structural reinforcements. Often, customers will also take advantage of the enforced downtime to do other jobs, like for example to review speed and maximum load related performance characteristics, albeit addressing these does require changes to drives, motors and/or gears.

Preparation work, involving engineering and detailed project planning, usually takes two to four months. In terms of actual crane downtime, this can vary from six to ten weeks. A jacking system that lifts the crane from the ground can take longer to set up, but once it is ready, the heightening work can be repeated much more quickly in multi-crane projects than if the crane were to be lifted from the sill beams with the weight on the rail span. The latter is a safe choice when the limits for maximum ground pressure would otherwise be exceeded, or are not known for certain, explains Mr Vuojolainen.

Asked whether, given all the disruption, it wouldn't be cheaper to buy an entirely new crane and sell existing units second hand, Mr Vuojolainen points out that the second hand market for gantry cranes is not particularly buoyant, due to the strict specifications of most cranes, allied to restrictions of individual quay sides and the high cost of relocation.

“So, in most of the cases, this is not an option,” he says.

“The cost of heightening an STS crane varies greatly, depending on the equipment and also on the heavy-lifting solution chosen. But, as a rule of thumb, heightening alone costs in the region of €1.2m per crane.”

Big picture

Heightened cranes are typically between 5 and 15 years old, with the average lifetime of an STS crane being about 25 years, depending on the number of moves or work cycles it undertakes. For newer equipment, this kind of upgrade essentially means changing the physical dimensions of the crane; for older equipment, other upgrades will probably need to be undertaken at the same time. These can include, for example, the addition of modern crane monitoring systems and a new operator cabin.

And what about the possibility that heightening work could have negative, operations effects on the crane? To avoid this, Kalmar undertakes a rigorous feasibility study; the project will only then be carried out if no critically negative effects are identified.

Analysing crane loadings determines the weak points where cracks are likely to form, or small cracks may have emerged. Reinforcing these locations can increase the STS lifetime by around one or two million moves. In fact, most STS cranes are designed to withstand two to four million moves. Therefore, analysing the crane and addressing structures during a heightening project often results in positive overall improvements.

“Calculating the return on investment based on the decision to heighten the crane or not is hard to calculate,” he adds. “This is because the terminal needs to make a strategic decision whether it wants to serve really large vessels, or concentrate on more modest ones. In a case where they decide not to heighten the crane, they clearly won't be able to serve bigger vessels. But calculating a value for such lost opportunity is not straightforward mathematics.”

Nevertheless, a terminal operator can make a comparison in terms of capital expenditure of the heightening of an existing crane or buying a new crane.

“As a rule of thumb, when the existing crane is structurally sound and low height is the only main concern, heightening such cranes invariably works out more attractive than acquiring new equipment,” he says.

Heightening just one piece of the puzzle 

The majority of the crane heightening projects undertaken by Kalmar so far have been on third party units, which often leads to other improvements as increasing height and outreach cannot be undertaken in isolation.

For heightening, a critical consideration from an engineering point of view is the possible ground pressure limitations of the quay below the crane. This will determine what kind of jacking system can be used to lift the crane during heightening – a choice that also has serious cost and time implications.

“We discuss options open to the terminal following a detailed engineering study. During heightening, the portal structure of the crane is strengthened to maintain stiffness and allow increased loads to be handled. Elevator, stairs, cables, drums and hoists also have to be modified according to the new height,” he says.

Some cranes have bolted connections in the crane legs, which makes upgrading the crane much easier. Nevertheless, Kalmar can also upgrade the legs even when bolted connections are not present, although this requires more work.

“Extending the outreach of the boom is, from a technical and price perspective, a bit more challenging. The stability and wheel loads of the crane have to be taken into consideration,” he says, pointing out that, by adding weight at the boom tip, the specifications of the crane need to be carefully calculated, which invariably results in further modifications.

There are also further costs associated with outreach extension: for example, renting a floating crane during the project as well as supplying two cranes on the quay to assure stability during the work.