| Since the 19th century, static electricity, an unexpected guest, has rushed into the highly developing industrial sections, and the tanker electrostatics has become one of the important factors that pose threat to shipping safety. For example, during December, 1969, the explosion of three VLCC occurred in less than three weeks, which greatly shocked the world shipping field.In china, static explosion accidents of tankers are also no rare occurrence, which result in heavy loss in lives and property. As is shown by the statistics, accidents caused by static electricity ranks the third among those. Therefore, there emerges felt urgency to deepen the research of shipping electrostatics, to work out comprehensive protective measures fitting in with China's actual situation and to offer crew necessary static security education.Tanker explosion caused by improper ship-shore electric joining happen with a relatively high frequency both at home and abroad, which puts high pressure on the safety of the tankers, docks and harbours. In order to prevent the accidents resulting from the electrostatic discharge and the stray current, ISGOTT( that is, International safety guide for oil tankers & terminals), the latest version by ICS( The international chamber of shipping ), IAPH( The international association of port and houbour ) and OCIMF( The oil corporation international maritime forum ), clarifies the following: During the period of loading and unloading, sub-conduction static-proof insulating flanges or nonconducting hoses must be installed between the ship and the bank( only one is permitted to use at a time). In addition, the application of bounding cables which have been used for years in China is prohibited. Use of static-proof insulating flange or nonconducting hose fulfils two purposes. Firstly, it can stop up the transmission of the stray currents along the ship-shore oil tubes; secondly, it can provide the passageway to the ground for statics.In order to meet international requirements, China must implement these regulations in real earnest. It follows that the development of sub-conduction static-proof insulating flange and nonconducting hose is highly necessary.The present thesis describes the electric double layer theory anddiscusses in detail the mechanism of static charge in conveying oil tubes. On this basis and in line with the international requirements for ship-shore electric joining, this paper describes our research result on new technology of ship-shore electric joining. The project is sponsored by the shanghai natural science fund.According to the reports and documents abroad, insulating rubber is ideal as a basic material. Its electric conductivity can be changed by adding conductive carbon black in it. By means of pressure adjustment and temperature control, the material can be moulded at a special temperature and then the sub-conduction static-proof insulating flange shaped by extrusion. Data collected from resistance test and mechanical performance test indicate that the sub-conduction static-proof insulating flange sample of the 8-inch oil tube accords with the demand of ISGOTT: R^ 25K Q. It also meets the requirement of China : R^2500 K Q. in real use, it is very important to ensure the insulation of the face to face bolts of the static-proof insulating flange. To reach the standard, high-intensity insulating rubber is chosen to make casing pipes and spacer. According to users'requirements, steel spacers are fixed on the outer layer of the insulating spacers. Thus, the demands for electric performance and the face to face bolts' fastening performance are met.The successful development of sub-conduction static-proof insulating flange not only contributes to the fully implementation of the ISGOTT's safety measures, but also provides technical supports to the safety of harbours, docks and tankers. It is of great social significance and high economic efficency. |
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