Increasing use of CNG is driving the need for robust tubes that can withstand the high pressures at which CNG is stored and transported apart from resisting corrosion, says Vikram Pandit.
According to the estimates of the Petroleum and Natural Gas Regulatory Board, currently, there are seven lakh natural gas vehicles in the country. This is expected to increase to 58 lakh over the next ten years. Delhi alone has more than two lakh vehicles. Around 30 cities have access to CNG and some of them have implemented the program to good effect. The CNG pipeline network will increase to 15,000km and implementation of city gas distribution network will cover around 150 to 200 cities by 2014. This potential can be further exploited if the natural gas distribution network is expanded and strengthened. Looking at the statistics there is an absolute need to make sure that safety is not comprised at any level.
Termed as the fuel of the future, CNG is used at high pressures and under severe conditions. To ensure complete safety of the people and to make it more successful, it is essential to use special tubing for transportation applications. Especially in the range of 230 and 250bar. This is the pressure range at which CNG is stored and transported at gas stations, and in the vehicles; making it imperative for the tubing to withstand such high pressure of the gas within it, and also resist corrosion on the outside. Committed to develop and design special tubing, which would fulfill all the safety parameters, Sweden-based Sandvik Materials Technology has developed CNG high pressure fuel line that has become a benchmark in reliability and safety when it comes to handling CNG under high pressures and extreme conditions. One of the most important parts of the CNG system of a vehicle, the fuel in the form of gas from cylinder is supplied to the engine using a network of these tubing. Apart from corrosion resistance and high pressure handling, the requirement is the ability to bend.
There has been a tremendous amount of metallurgical development with respect to the materials during the last few decades. There’s been an amount of development when it comes to high pressure CNG fuel lines too, in terms of the material of construction. Starting with C-steel tubing, there’s been a lot of R&D at Sweden as well as in India. The outcome was a dual grade certified 316/316L tubing. Some important specifications apart from the Standard ASTM A 269, which needs to be taken care for the material of construction of high pressure CNG tubing include the chemical composition. (Chemical Composition: per cent C – max 0.03 per cent; %Ni – min 13.0 per cent; per cent Mo – min 2.5 per cent). The tubing is produced by hot extrusion process followed by cold pilgering and drawing for the best results.
Used as an alternate fuel, the quality of CNG depends upon the percentage of methane present. To enhance the CNG storage capacity on vehicle it is compressed to 200-220 kg per square centimetre (bar). This calls for a tubing, which can withstand high pressures as well as a harsh operating environment, for almost the whole of the life of vehicle. Since there is no governance, or rules and regulations for checking these vehicles it is of utmost importance that the tubing is of top quality and standards. The dual certified grade 316/316L tubing takes care of the all the concerns. With its special chemical composition, it is able to meet the tough demands of the application.
For further information contact: Vikram Pandit, Product Manager, Sandvik Asia, at email@example.com
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