When the massive Storebaelt bridge was built in Denmark in the 1990s, a crane barge and a bridge lift system were specially built for the project. Both were built in 1993 by the Dutch company Huisman-Itrec for Smit, also of the Netherlands. The 3,000t capacity Taklift 8 was used to lift one end of each bridge element as it was put in place; the 1,350t Taklift 9, sitting on the most recently placed bridge section, lifted the other end.
As early as the design phase, it was always anticipated that the A-frames would one day be combined, with the Taklift 9 being used as jib on top of the Taklift 8 A-frame. Lengthening the main A-frame and adding a back frame to allow the jib to luff were also envisaged. As things turned out, work for such large crane barges fell away and Smit decided to sell both the Taklifts 8 and 9 without doing the conversion work.
The buyer was the Iranian company SADAF, which has recently followed through with the conversion work to create the SADAF 3000 – the largest floating sheerlegs in the Gulf region and one of the largest in the world. SADAF’s previous biggest crane barge was the 400t capacity SAFF 400. For heavier lifts it previously had to rely on subcontractors like Seaway Heavy Lifting. Typical worked carried out by SADAF is the up-ending of jackets and installing topsides on oil platforms, mostly for the Iranian state oil company Petroiran.
SADAF’s first thought was to contract Huisman-Itrec to carry out the barge conversion. Then to reduce costs the company decided to do the work itself. Since many of the parts are made from high tensile steel (S690 QL), the Iranians had to develope appropriate welding procedures. However, they did not have the engineering capacity. At the suggestion of some people from Smit, SADAF commissioned Schouten Engineering Consultancy BV to do the necessary design work. Schouten Engineering Consultancy was founded in 1996 by Amarinus Schouten, who had previously been invovled as a design engineer in the original construction of the Takllifts 8 and 9. The company does engineering activities in offshore, heavy transport, installation and crane building for companies like Mammoet, Huisman-Itrec and Smit, with whom it worked on the lifting of the Kursk submarine in 2001.
Schouten produced engineered drawings for the full conversion. One of the first drawings was the 13.3m A-frame length extension. This meant cutting the head section off and welding the extension in between. However, during this work it was also calculated that the barge did not have sufficient stability. Without increasing the width of the barge, the potential capacity of the crane could not be fully used.
But then SADAF came with a new plan to do the conversion only partly to be ready in time for a particular installation project, namely the installation of Salman field jackets 2SK-B and 2SK-C. Instead of fully converting the Taklifts, it was decided to do just a ‘phase one’ conversion job for the time being. The proposal was to place the Taklift 9 directly onto the Taklift 8 A-frame at its original length. This version was named SADAF 2000. To reduce the work even more, the luffing frame and the jib adjustment function were left out. Engineers at Schouten confirmed that the lifting and upending of the Salman field jackets was possible with the fixed A-frame and jib angles, and they prepared the engineering for the barge to be converetd specifically to meet the needs of this installation job. Specialist calculations on pile driving was outsourced to Fugro Engineering. In November and December 2003 the crane was built as such. In February 2003 the installation activities started and were finished successfully a month later.
Now the crane – the SADAF 2000, as it still is – is back in the yard and is being prepared for another installation job. Two 41t capacity winches from what used to be Taklift 9 are being installed to enable jib adjustment. A dedicated set of lifting curves are defined and in the process of being approved by Lloyd’s Register in Rotterdam.
SADAF intends to go ahead with the third and final stage of the conversion project, but the timing is uncertain at the moment until the financing is in place. The plan is to lower the A-frame and install the extra section to extend the length of the jib. Also the luffing frame and the winches for operating it will be built and installed. After that, the crane itself will be totally finished. The barge, however, still requires side pontoons to be welded onto it, increasing the overall width from 30m to 40m to give the vessel sufficient stability for the crane to lift to its maximum potential. The barge width extension may be carried out in a fourth phase. The narrower 30m barge the crane can still operate, but at a reduced capacity.
When both crane and barge have had their complete conversion, the lifting capacity will be 3,000t in harbour conditions. Dedicted lifting curves for Hsig = 1.25 m associated with sheltered waters are defined based on dynamic analysis by Technical University Delft. The vessel will have a classification by Lloyd’s Register.
