Nanjing Electric Insulator Co., Ltd. is the largest producer of electrical insulators for high-voltage transmission lines in China. In 2014, SORG received the first order for the delivery of a regenerative end-port furnace with a working end and two forehearths for the manufacture of such insulators. 

The insulators produced by Nanjing are subject to a very tight glass chemistry specification, which is different for direct current (DC) and alternating current (AC) insulators. With an article weight of up to 12kg, extreme demands are placed on the glass in terms of glass homogeneity, melting relics, and inclusions from unmolten batch particles and seeds. Later failures of the insulators are not permitted.  

The first furnace delivered by SORG exceeded the requirements regarding the factors mentioned above and the operating time. Nanjing Electric Insulator has commissioned SORG to deliver a further system.  

 In addition to the technical factors, it is important to note that excellent know-how, advice, and service from SORG contributed to this decision. 

 To comply with the Chinese government’s new emission regulations, a SORG VSM® type all-electric melter was supplied. 

This new VSM®, with a melting surface of around 20m², a STW working end and a forehearth STF 340S+®, is specially designed for the production of soda lime flint glass for the production of the insulators. Insulators suitable for AC and DC are produced with this furnace, and the weight of the items is up to 12kg. 

 The VSM® is charged with the batch via the well-proven rotating crown, while SORG Top electrodes ensure the energy input into the melt. A filter cleans the superstructure atmosphere. 

 To meet the high demand of glass quality, the facility has SORG CONTI-DRAIN® systems installed on both the throat of the furnace and in the forehearth channel. Furthermore, a SORG universal stirrer unit is installed in the forehearth. 

The customer was highly satisfied with the SORG technology and emphasised the outstanding service and support. 

In a gracious ceremony, some of the SORG employees were made honorary members of the Nanjing Electric company.