the application and advantages of copper nickel pipe seawater system in drilling platform
At present, the commonly used seawater pipeline on the drilling platform is mostly made of carbon steel, which is prone to corrode after being used in seawater system. Combined with the physical characteristics of copper-nickel alloy pipe, this essay comprehensively introduce the application and advantages of copper nickel seawater system in drilling platform, which can provide reference for later platform.
Key Words: copper nickel pipes , the Corrosion of copper – nickel alloy , drilling platform
At present, mostly used seawater pipeline in the drilling platform commonly are made of carbon steel material, which are easy to be corroded after being impregnated in the seawater. The platform of the water pipeline contains piping, pipe fittings, pumps, valves and related equipment. In the meantime, there are also more complicated chemical corrosion phenomenon. Being exposed in marine environment for a long time, carbon steel pipeline exists static seawater immersion, flowing seawater corrosion, pitting, stress corrosion, internal crystallization corrosion and electrochemical corrosion. The corrosion of carbon steel pipeline is easy to be corroded in the seawater, which will will have an impact on drilling platform production , thus the corrosion resistance of copper and nickel alloy tube is more and more applied in the offshore drilling platform.
1, The drilling platform seawater system
1.1 Brief introduction of drilling platform seawater system
In the drilling platform, the pipeline system mainly includes seawater system, fresh water system, mud system, ash supply system, fuel system, etc., among which seawater system is one of the largest platform , seawater pipings are equipped in almost every corner of the platform, mainly distributed in the cabin, the main deck, drill floor, living floor and so on. The submersible pump in the drilling platform on are put down into the sea, and the seawater will be transported to the platform through the pump, which mainly commitment to cooling, fire, stowage, mixed and some other functions.
1.2 Design and material selection of seawater piping
Due to the different sweater piping branches according to its functions in the drilling platform seawater system, there are many branches, reducer and elbow. The long-time usage of ordinary carbon steel pipeline may cause erosion and internal crystals, and it is easy to gather in the pipeline within the sea creatures, resulting corrosion or clogging in the pipeline, the The corrosion pit and leakage of seawater pipelines, will gradually expand under the pressure point,which can only be replaced. And there are many electrical equipment on the drilling platform. If the seawater leak into the electrical equipment, it will increasegreater risks. Therefore, considering the special material of anti-pressure and anti-acid and alkali inseawater pipings, the current optional pipe are the glass pipe, stainless steel tube, copper nickel alloy pipe, and steel pipe contained inert element.
2, Characteristics and application of copper nickel alloy pipeline
According to the physical characteristics of copper-nickel alloy pipe, are added during the production of pipelines. The current commonly used is copper nickel UNS C70600 CuNi90 / 10 .Copper is internationally recognized as a better material of corrosion resistance. The pipeline strength and toughness are greatly increase after adding nickel element. So it has the physical characteristics with wear, high temperature and high pressure, anti- corrosion of acid and alkali which can be used in more stringent conditions.
2.2 The advantages of using copper-nickel alloy
Copper-nickel alloy pipe is resistant to seawater impact, and with good corrosion performance, It can form a protective film on its surface to prevent further corrosion in the seawater.In the drilling platform seawater system, there are many branches, diversion and elbow. The good mobility of copper-nickel alloy tube can resist seawater erosion corrosion and the attachment of sea creatures, which minimize the daily maintenance of the platform to a great extent. There are more complex electro chemical corrosion in the drilling platform. Pure copper added with nickel can significantly improve the strength, corrosion resistance, hardness, resistance and thermoelectricity, and reduce the resistivity temperature coefficient. What’s more it can reduce the electrochemical corrosion and delay the service life In the drilling platform, the seawater system is a relatively large system, the largest diameter is 12 “. Currently the most commonly used copper-nickel alloy tube (CuNi-90/10) has a thinner wall than carbon steel in the same system pressure, including flange, tee and other pipe accessories.According to the calculation, the using life of the ordinary carbon steel pipeline is about 3-5 years, while the copper-nickel alloy pipeline life can be extended to more than 10 years.
2.3 The typical application of copper nickel alloy tube
According to the physical characteristics of copper-nickel alloy tube, it can be widely used in drilling platform seawater system, in the sametime, it can be applied to other pipelines in the marine facilities.Due to the difficulty of welding between copper-nickel alloy pipes and steel plates, it is usually used in combination with carbon steel pipe fittings. For example, in the cabin, the hull cabin panel is made of steel plate, so the need to use carbon steel to wear cabin and flange, in the cabin on both sides of the wall in the connection of copper and nickel alloy tube.Due to the price of copper-nickel alloy pipe in the market, the rectification system can be used in conjunction with the carbon steel pipeline considering total cost. For example, in the often used or easy to repair the area, you can choose carbon steel pipeline; and in the area which is not easy to repair, you can use copper and nickel alloy pipe.In the use of copper-nickel alloy pipeline and carbon steel pipeline, the insulation of pipe fittings must also be considered. Usually the tube support is made of carbon steel material, the insulation pads are added in the bracket and the pipeline bracket, to avoid direct contact causing electrochemical corrosion. Insulating materials are also usually used in the bolt connection holes between the carbon steel flanges and the copper-nickel alloy flanges. When it is difficult to control the weight, copper-nickel alloy pipe also plays an important role. It can replace the ordinary pressure pipeline according to the calculation.
3 The conclusion
With the gradual development of the marine field, the combination of ordinary carbon steel pipe and copper-nickel alloy pipeline has been gradually recognized by everyone. The advantages of using copper nickel alloy pipe appear step by step. Combined with the copper-nickel alloy pipeline used in the drilling platform, this essay introduced the physical characteristics of the copper-nickel alloy tube in detail and suggest some operational guidance according to its applications for everyone to adopt.