It is reported that in recent years gas consumption in China has increased sharply and so it has become critically important to improve the energy supply throughout the country. To accomplish this, China is accelerating exploitation of domestic resources and importing oil and gas from nearby Russia and Central Asia. For the transmission of gas from the west of the country to the southeast, the China National Petroleum Corporation is building the Second West-East Gas Pipeline.
This gas pipeline has a total length of 8,660 kilometers consisting of one main pipeline and six branch pipelines. It passes through 13 provinces from Huoerguosi in Western China to Shanghai, Guangdong and Guangxi province in south-eastern China. It is an important pipeline which will connect gas resources in Central Asia, Talimu, Zhungeer, Tuha, Changqing and Longgang with the markets in south eastern China.
The pipeline is initially designed to provide 30 billion cubic meters of natural gas annually from Central Asia. In a release, CNPC said the trunk line will use 2.8 million tonnes of X80 grade steel pipe, consisting of 2 million tonnes of spiral submerged arc welded pipe and 800,000 tonnes of longitudinal submerged arc welded pipe. The branch lines will use 1.6 million tonnes of X70 grade steel pipe. China's leading SSAW pipe maker Baoji Petroleum Steel Pipe Co. has supplied 328,000 tonnes of pipes for the project. Baosteel and Heibei-based Julong Steel Pipe are the main domestic LSAW pipe suppliers. CNPC also imports LSAW pipes from foreign pro¬ducers, mainly located in Japan and South Korea.
1. Around 10,000 tonnes of moly to be used
High Strength, Low Alloy steel grade X80 pipes with a diameter of 1219 mm will be used along the full length of the main line. The pipeline will be divided into two parts, one section with a pressure of 12 MPa from Huoerguosi to Zhongwei, the other with a pressure of 10 MPa from Zhongwei to Guangzhou. According to operating pressure and area class, six kinds of pipe with a thickness from 15.3 mm to 33 mm will be installed. The branch lines and the connecting lines will use X70 line pipes with 10 MPa internal pressures.
Several major Chinese steel companies have developed X80 hot strip and plate products for spiral pipe and longitudinal pipe production, respectively targeting a 60% domestic steel supply to the project. The low carbon, high niobium base metallurgical concept provides high strength and excellent toughness due to the acicular ferrite microstructure that is typical for such alloys. Between 0.2% and 0.3% Mo is added to the steel to retard the formation of primary ferrite and pearlite and to compensate for an insufficient cooling rate, especially when heavy gages are to be rolled. For this mammoth project 4,400,000 tonnes of moly grade steel will be required containing in the order of 10,000 tonnes of molybdenum.
2. Record-breaking pipeline
The Second West-East Gas Pipeline is unprecedented among the world's X80 pipelines. It is the longest X80 pipeline in the world, crossing all kinds of terrain and geographic and weather conditions in China. The western section of the pipeline will be constructed from February 2008 to the end of 2009 and the eastern section will be constructed from September 2008 to June 2011. The project is scheduled to be completed by the end of 2011.
CNPC will import natural gas via the 1,818 kilometers long Central Asia-China gas pipeline which is being built from Turkmenistan and Kazakhstan to Xinjiang Uygur Autonomous Region in the north-west of China where it connects to the Second West-East Pipeline. According to CNPC, the inflow of Turkmen gas will significantly help China in meeting its energy demands and will stabilize the country's overall consumption structure. Turkmenistan will diversify its energy exports by delivering gas eastward as opposed to its current deliveries to Europe via the Rus¬sian Federation.
The pipeline, the second after China's first West-East natural gas pipeline, which went into operation in 2004, is considered significant for improving China's energy consumption mode. The government plans to raise the ratio of natural gas in its energy consumption structure by 2.5 percentage points to 5.3% by 2010. According to estimates by CNPC, the full operation of the Second West-East Pipeline will raise its ratio by one to two percentage points, while replacing 76.8 million tonnes of coal and reducing emissions of sulfur dioxide by 1.66 million tonnes and carbon dioxide by 150 million tonnes.
The first West-East pipeline, which pipes gas from the Tarim Basin of Xinjiang to Shanghai, transmits 12 billion cubic meters of natural gas annually. Very recently it was decided to build a second string parallel to the Second West-East gas Pipeline that would double the capacity and secure an additional 30 billion cubic meters of gas per annum for Chinese consumers and industry.
(Sources: Moly Review January 2009 from IMOA)
