The first major undersea stainless steel pipeline was built during World War II. Nicknamed Operation PLUTO (Pipe Line Under The Ocean), this stainless steel pipeline stretched 70 miles across the English Channel, connecting the Isle of Wight with the coast of France. The construction required 46 tons of building materials per mile. Operation PLUTO was intended to provide a safe way to transport fuel to Allied tankers. To keep the stainless steel pipeline secret, pumping stations along the route were disguised as garages and other inconspicuous buildings.
Over sixty years later, the basic purpose of underwater stainless steel pipelines remains fuel transport. As natural gas deposits are discovered under the ocean, raw fuel must be transported to refining facilities. Stainless Steel Pipelines serve to fill this need. When the gas has been refined, separate stainless steel pipelines are used to load the liquefied natural gas to fuel tankers. Undersea stainless steel pipelines also provide an environmentally-friendly method of fuel transportation. Since the installation of stainless steel pipelines does not require a prolonged disturbance of the seabed, biologically fragile areas can be spared needless disruption.
As technology has improved, polyethylene piping has begun to be used in underwater stainless steel pipelines. These pipes are generally coupled using screw anchors and saddle clamps. Steel buckles are also used in marine applications. Stainless steel pipe flanges are also common in undersea stainless steel pipelines, and indeed 316 stainless steel as used by manufacturers like ISO Stainless Steel is preferred by many for marine applications. That is because the 316 type of stainless steel is particularly resistant to corrosion. 316 stainless steel is composed of several types of metals added to the steel to protect it from corroding.
A stunning example of undersea stainless steel pipeline technology at use is the recent Langeled Pipeline, which connects Norwegian North Sea oil fields with processing plants in Britain. It stretches an astonishing 746 miles to bridge the gap between the two countries, over underwater terrain so rough and rocky it required two robotic diggers working tirelessly to clear the space for it. At its deepest the stainless steel pipeline lays in 2953 feet of water (with water pressure of 1500+ psi!). The $3.3 billion stainless steel pipeline was laid piece by piece with pipe welded on two floating “pipe factories” – ships on which the pipes were secured before being placed on the ocean bottom.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)