RECONSTRUCTION OF GAS DISTRIBUTION PIPELINES IN MOZG IN POLAND USING PE AND PA PIPES

摘要

MOZG - Warsaw Regional Gas Distribution Company was established in 1856. Now it is one of six gas distribution companies in Poland and covers about a quarter of the area of our country. We serve 1.8 million customers in total. The total length of our distribution network is approximately 20,000 km and the quality of the greater part of our pipelines is suitable for the current level of demand. However, approximately 150 tan of our network is made of steel or cast iron constructed pre 1955. Additional some 3000 km of piping is between 15 to 40 years old. Due to steadily increasing safety demands, some of the pipelines will need reconstruction. The majority of the substandard piping is located in urban areas; It is common to find gas pipes buried under roads and pavements along with other utilities (water, sewage, power and communications) leaving these underground areas crowded. Also due to the recent increase in "traffic volume" it has become more and more difficult to conduct pipeline reconstruction by conventional "trench excavation" pipe replacement techniques. Therefore, the need exists for using an alternative more advanced method of reconstruction. A variety of advanced methods have been developed and applied in many countries all over the world, including Poland. Having analyzed the methods available, bur company decided to undertake some trial reconstruction projects. We wanted to gain experiences in applying reconstruction technologies using two different plastic materials polyethylene and poliamide. We also wanted to assess the technical and economic practicalities of perforating relining processes. In our opinion the following projects: 1. PE project -large diameter polyethylene relining (Φ 450 mm) conducted in Warsaw in 1994/95 2. PA projects - relining using poliamide pipes, projects conducted in Radom and in Warsaw during 1993 and 1994 are the most interesting and representative for this kind of works. Thanks to the experience obtained whilst carrying out these projects, reconstruction of old gas pipelines has become routine. Now we often use polyethylene relining of smaller diameters (20 ÷ 335 mm) and we continue both construction and reconstruction of gas network using PA pipes. Today we have about 75 km of pipelines reconstructed by PE relining and over 100 km of PA network (20 km of new and 80 km of reconstructed pipelines).