What Are The Methods For Laying Submarine Pipelines?

The China Submarine Pipeline Installation is completed by a submarine pipeline. The design considerations of the Offshore Pipe Installation Company are numerous, and the installation construction is to overcome all risks. The first is that the operating environment is in the ocean. Not only is the operating space severely restricted, but the complex and changing sea conditions will also bring great challenges to normal construction. In addition, the seabed environment is complex, not just a flat river. It is composed of various topography and landforms, such as high seamounts, rolling hills, long ridges, and deep trenches. We can't transform the seabed geomorphology like laying pipelines on land, so no matter the design or construction process, the consideration of laying submarine pipelines is very complicated. The problems of low temperature, high pressure, high salinity, undercurrent surge, hydrate blockage, pipeline corrosion, and impact loss will continue to exist. The coexistence of these problems makes the laying of subsea oil and gas pipelines not only an engineering problem, but also a scientific problem.

So, how is the submarine pipeline laid? For the Submarine Pipe Installation Service, water depth is the biggest influencing factor. According to the different water depths, pipe laying operations are very different.

Submarine Pipe Installation Service

(1) In places close to the shore and in shallow water, the winch can be used to directly pull the sea pipe to the land.

(2) Pipes can be laid in the shallow sea area and far away from the shore by way of laying down and welding at the same time. S-Lay (S-type laying method) is mainly used: the submarine pipeline enters the water through the stern holding frame, forming an S-shaped curve and laying into the seabed. During the pipe laying operation, there are 3 artifacts on the ship-tensioner, stinger and welding line. The tensioner is used to fix the sea pipe, like a big clip to hold the sea pipe. The custody rack is used to control the laying direction of the sea pipe. In addition, due to the limited space for offshore operations, laying a submarine pipeline requires a professional fleet to cooperate with each other to complete the construction, and the cost is 1 to 2 times higher than the land under the same circumstances.

(3) Pipe laying operations in deep water areas increase the water depth, resulting in an exponential increase in construction difficulty. The increase in the length of the submarine pipe leads to an increase in weight, which requires the pipelaying vessel to withstand greater tension. At this time, the J-Lay method is used for construction. J-Lay (J-type laying method): The submarine pipe leaves the pipelaying vessel in a near-vertical form and descends along the vertical bend until it is laid into the seabed. The overall pipeline is "J" shaped, suitable for hundreds of meters to thousands Meters in the deep sea area.

(4) With the continuous development of new technologies, the form of offshore pipe laying operations has been continuously improved. For submarine pipes with small diameters and slightly weaker strength, they can be manufactured on land and directly wound on drums, and transported to sea by pipelaying ships. This operation method is called Reel-Lay (rolled pipe laying operation) . At present, the coiled pipe laying ship can be divided into two types of horizontal and vertical. For horizontal coiled pipe laying ship, the axis of rotation is perpendicular to the deck of the pipe laying ship, and the S-shaped laying (commonly used in shallow water) is commonly used for laying umbilical cables; for vertical coiled pipe laying ship, the axis of rotation is the same as the pipe laying vessel The deck is kept level and is laid in a J-shape, which is often used in deep water. Of course, which operation method to choose in the end is not only to consider the water depth, but also to combine the comprehensive factors such as operation cycle and operation cost.

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