Seabed oil (gas) pipeline
Undersea oil (gas) pipeline is a major component of the offshore oil (gas) field development and production system. It is continuously supplying a large number of oil (gas) the fastest, the safest and most economical and reliable mode of transport. Linked by submarine pipeline offshore oil (gas) can be field production gathering and storage systems, also linked to the offshore oil (gas) fields and onshore oil industrial systems. In recent decades, with the continuous development of the offshore oil (gas) fields, the undersea oil (gas) pipeline has actually become an effective means of transport is widely used in the offshore oil industry.

Ocean seabed oil (gas) pipeline in China are mainly distributed in the Bohai Bay, Liaodong Bay, Yellow Sea, the northern East China Sea, the Pearl River estuary in the South China Sea and Yingge Sea and other places. According to statistics so far, the submarine pipelines have been built more than 2000 km, 11 of which the Bohai Sea oil (gas) Tian Jiancheng submarine pipeline accumulated more than 200 km to the South China Sea 15 oil (gas) fields laying submarine pipeline accumulated more than 1000 km certain offshore gas field from Hainan Island to Hong Kong a 711 film (28 inches) in diameter submarine gas pipeline about 800 km long, is the longest a submarine pipeline. In addition, a gas field in East China Sea near Shanghai, the laying of an oil, gas an undersea pipeline a total of 800 km.

Characteristics and classification of submarine pipeline
Submarine pipeline has the advantage of continuous transmission, almost free from the influence of environmental conditions, will not force oilfield production or discontinued due to capacity constraints of offshore oil storage facilities, or not timely pick up of the shuttle tankers. High efficiency, so the oil tanker capacity. Another undersea pipeline laying duration is short, and put into production fast, easy management and low operating costs. The disadvantage is that: in a seabed pipeline, most need to be buried at a certain depth in the seabed soil, inspection and maintenance difficulties, higher cost. Some in the tidal range or wave breaking with the pipe (riser), subject to the influence of wind and waves, tide, ice, etc., may sometimes be damaged floats in the sea and the ship crash or breakdown. Our waters have been many incidents of fishing vessels to fight nets destruction of the submarine pipeline accident.

Submarine pipeline transmission medium can be divided into submarine pipelines, submarine gas pipeline, undersea oil and gas mixed transportation pipelines and undersea aqueduct from the structural point of view can be divided into the pipe and single pipe of the double insulation.

China's submarine pipeline with the development of the pipe
Submarine pipeline material selection must meet the design and offshore pipe laying and construction requirements. With the industrial development of submarine pipeline, the pipe reliability have become increasingly demanding, but the submarine pipeline pipe manufacturing methods are no special requirements, such as seamless steel pipe, a variety of shielded arc welding straight seam steel pipe, etc. can use. To meet the design and installation requirements under the premise, to choose the most economical pipe.

With the expansion of China's offshore oil development, submarine pipeline construction after years of continuous exploration and improved in terms of the key processes of the construction group, welding, testing, and other more scientifically sound. Trend of submarine pipeline construction, high efficiency and high quality construction, process technology have become increasingly demanding, particularly on behalf of the level of submarine pipeline construction welding technology, improve submarine pipeline steel strength grade , the performance of the development pipeline welding technology and high production efficiency, high cost performance of the automatic welding process is a priority, in order to adapt to the pace of development of the submarine pipeline construction.