Tipos de sistemas de estimulación en la ECP

More often than not, modern equipment is simply a scaled-up version of the technologies first proven on the early LNG carriers

A SIGTTO/GIIGNL commemorative issue 44 I

44 ILNG shipping at 50

Wheeler was responsible for the boiler design and the engineering of the firing equipment, automatic controls and the boiler instrument panel.

The Scottish engineering firm Munro & Miller of Edinburgh was another supplier. Five years earlier the company had provided 150mm and 200mm diameter expansion joints for the cargo piping systems on Methane Pioneer . The success of that vessel’s trial shipment programme prompted Conch Methane Services to order a total of 190 Munro & Miller expansion joints for Methane Princess and Methane Progress. The equipment accommodated the thermal expansion and contraction of the vessels’ fixed piping systems.

The company’s success in the LNGC field continued when it was contracted to supply 555 expansion joints of between 50 and 400mm in diameter for the cargo piping systems on the four 41,000m3_{Esso Brega-series ships built in}

Italy and Spain later in the 1960s. The most common liquid level float gauge on the early LNG carriers was from Whessoe Systems and Controls of Darlington in the north of England. The Whessoe float gauges that had been widely used on pressurised LPG carriers required some changes to component materials to ensure suitability for the new LNG application. LNG carriers must also have in place a secondary means of top level measurement and on the early vessels this was achieved through the provision of a toughened glass sight gauge in the cargo tank dome with a measuring scale visible below inside the tank.

The distinctive shape of the Luceat pilot-operated safety relief valves (SRVs) arranged in pairs on LNG carrier cargo tank domes was first seen on Jules Verne. The pioneering French ship was fitted with 14 such SRVs, two per cargo tank and each 6 inches in diameter. The relatively low maximum design pressure employed for fully refrigerated LNG carrier cargo tanks requires accurate and delicate pressure control. With the Luceat valve the tank pressure was determined by a pilot diaphragm with a large surface area to amplify any small variation in the tank pressure. The valve was of rugged construction, the delicate pilot diaphragm being fully integrated into the valve housing head. Most of the early LNG carriers built in Europe were fitted with Luceat pilot-operated SRVs.

French engineering components were encouraged and commonplace on Jules Verne. The vessel was fitted

with two 450 m3_{/hour stainless steel}

Guinard SEMPs in each of its seven cargo tanks. Having been successfully tested onBeauvais, Hibon Pompes Roots blowers were installed on Jules Verne

to supply boil-off vapour to the boilers and for gas-freeing cargo tanks. Hibon supplied a wide range of Roots blowers to many of the early European-built LNG carriers with the French membrane cargo containment systems.

Another two companies whose names were to become familiar in LNG circles were associated with the construction of the independent, prismatic-shape cargo tanks for the four ships in theEsso Brega

series. Chicago Bridge & Iron (CB&I) built the four double-walled cargo tanks required for each ship in Italy, using aluminium supplied by Kaiser. Air Liquide contributed a 22,000-litre nitrogen tank for each of the quartet, for purging and inerting the cargo tanks’ inner barrier spaces, hold void spaces and cargo compressors.

Two centrifugal compressors manufactured by Paul Airco Cryogenic of California were fitted in a deckhouse room within the cargo area on each of the fourEsso Brega series ships. Driven by a coupled steam turbine, the compressors were used to deliver cargo BOG to the main boilers. The Airco package for each vessel included two cargo heaters, a control panel and associated equipment. MSA of Pittsburgh supplied a fixed gas detection system in the cargo control room on each of the Esso ships.

The breakthrough order for Gaz Transport, when it was contracted to supply its membrane containment

system for the 71,500m3_{Polar Alaska}

and Arctic Tokyo building at Kockums in Sweden, brought the manufacturers of non-traditional shipbuilding materials into the LNG arena for the first time. The key components of the ships’ Gaz Transport system were the invar primary and secondary barrier material and the plywood boxes filled with perlite used as insulation.

The 36 per cent nickel steel alloy invar had been developed in the 1920s by the Imphy Division of Société des Forges et Ateliers du Creusot (SFAC) as a material with a very low coefficient of thermal expansion. The only manufacturer of invar, the Imphy steelworks had to step up production to deliver the required sheets forPolar Alaskaand Arctic Tokyo.

Kockums contracted the Finnish company Kaukas to supply the containment system’s perlite-filled plywood boxes. The loose perlite was not the easiest material to handle and protective masks and gloves were needed. The factory workers called this irritating material French snow. Kaukas was to become a key supplier of plywood boxes to Gaztransport and Technigaz (GTT) in later years.

Although LNG carrier construction has now switched from Europe and the US to Asia, many of the srcinal component manufacturers are still supplying their specialist equipment to the sector. While some may be operating under different names, they continue to promote the same proven technologies that have stood the industry in good stead over many years, sometimes as many as 50!SH

LNG Shipping at 50

LNG Shipping at 50||the pioneers

As the largest carrier