Design range offers high flexibility

German builder Lindenau has adapted one of its Tanker Class designs to suit the needs of a domestic owner.

The second of a pair of 13,050 dwt double-hulled IMO Type 2 chemical/oil tankers was completed by Lindenau GmbH, Germany at the end of November last year for domestic owner Carl Buttner Schiffahrtsgesellschaft, a regular customer of the yard over many years.

The sister vessels, Libelle and Hornisse, are being used by the owner to carry a range of mineral oil products, such as gasoline, diesel and naptha, between ports in Northern Europe.

The pair have classification society GL?s Finish/Swedish Ice class 1 B (E2) notation, and are based on Lindenau?s Tanker Class 2000 portfolio of designs, which range in size from 3,000 dwt to 40,000 dwt. In this instance, the owner specified an increase in deadweight of the yard?s 12,900t design to 13,050 dwt, and in cargo capacity from the design volume of 14,000 to 14,957m3. A high degree of flexibility in cargo that can be carried is provided by different tank sizes, and a high ratio of cargo tank volume to deadweight.

The hull is double skinned in way of the ten main cargo tanks and one slops tank. The double bottom, shell, innner hull and cargo deck have a longitudinal framing system, while fore and aft the hull has transverse frames. All inner cargo bulkheads are vertically corrugated. The deck stiffeners are outside on the weather deck in order to provide a smooth inner surface to the cargo tanks.

The vessels are capable of carrying IMO type 2 and 3 chemicals and oil products, depending on the coating resistance list. Maximum specific gravity of the cargo is 1.55 t/m3 in all cargo tanks. Each tank is coated with International Interline 904, and has stainless steel cargo piping and a Frank Mohn SD150 hydraulic stainless steel deepwell pump with a capacity of 250 m3/hr at 120 mlc, at 0.8 t/m3 specific gravity. The slop tank has its own Frank Mohn SD100, 100m3/hr capacity deepwell pump, which has a capacity of 110 mlc, also at 0.8 t/m3 specific gravity. One portable deepwell pump with a capacity of 70 m3/hr at 70 mlc, at 1 t/m3 is also specified.

An hydraulic power pack, comprising 3 x 255kW for simultaneous operation of six cargo pumps is also supplied.

There are five grade segregations, five manifolds with manually operated butterfly valves, and one crossover for each manifold with remotely operated double segregation valves.

All tanks can be loaded simultaneously at a maximum loading capacity per tank, with P/V-valves active, of 300 m3/hr at 8 bar. With vapour return via the manifold this capacity increases to 1,000 m3/hr in total.