1. Offshore oil and gas development

Oil is the lifeblood of a country's economy. It is estimated that the world's exploitable oil reserves are 300 billion tons, of which the seabed oil reserves are about 130 billion tons. The development of subsea oil began in the early 20th century. Its development has gone through the process from near sea to far sea, from shallow sea to deep sea. Restricted by technical conditions and material development, initially only the oil and gas deposits extending directly from the coast to the shallow sea can be exploited. Since the 1980s, stimulated by the energy crisis and technological progress, offshore oil exploration and development have developed rapidly, and offshore oil development has rapidly advanced to the continental shelf, gradually forming a new offshore oil industry sector. The offshore drilling platform is the work base for subsea oil and gas exploration and exploitation, and it marks the level of subsea oil and gas development technology. Offshore oil extraction equipment mainly includes oil production platforms and auxiliary equipment, and auxiliary equipment includes crude oil coolers, oil risers, pumps, valves, joints and fixtures, etc. These devices are all in contact with media such as sulfide, ammonia and chlorine in seawater and crude oil. Due to the excellent corrosion resistance of titanium in these media, the United States used titanium-made offshore oil platform pillars in its oil fields in the early 1970s, and also used titanium to manufacture shell-and-tube heat exchangers and plate heat exchangers. heater. The titanium shell and tube heat exchanger uses seawater as the cooling medium to cool the high-temperature steam/oil mixture drawn from the oil well. The titanium plate heat exchanger also uses seawater as the cooling medium to cool the fresh water used to cool the crude oil in the carbon steel heat exchanger. The United States uses approximately 100 titanium heat exchangers on North Sea oil rigs. The titanium components ordered by Hunting Oilfield Services Company in Aberdeen, Scotland, UK are said to be the world's first titanium high-pressure riser shafts, which are used in Conoco's Heidrum project in Norway.

Petroleum titanium alloy titanium drilling pipe has a long service life, its weight is only half that of stainless steel, but its use flexibility is twice that of stainless steel, and its service life is 10 times that of steel. These excellent properties make titanium an excellent material for drilling difficult near-circular and deep oil wells. Composite drilling tools containing titanium drill pipe can greatly reduce drilling time and reduce the overall cost of drilling. Titanium drilling pipes were first used in industrial applications in 2000 by GrantPrideco, RTI Energy Systems, and Torch Drilling Services in the United States. GrantPrideco and RTI Energy Systems co-manufactured and supplied the titanium drill pipe with steel tool joints supplied by GrantPrideco Anti-Fatigue. This joint is lightweight, flexible and makes the titanium drill pipe strong and strong.

Seawater pipeline system is an indispensable part of subsea oil exploitation. Since titanium has high corrosion resistance to seawater, its service life is 10 times that of steel system. Therefore, the cost of titanium pipeline system is more cost-effective compared with Cu-Ni system. of. U.S. Active Metals Corporation and Precision Tube Technology Co., Ltd. jointly established a titanium tube technology company to produce a large-diameter titanium alloy tube. The alloy used for this pipe is Ti-3Al-2.5V alloy, the diameter is 650mm, the wall thickness is 22-25mm, the length is 350m, and a pipe weighs 80-90t. It is planned to be used for subsea oil exploitation. Another company in the United States has used a seamless titanium alloy tube with a length of 15m, an outer diameter of 600mm, and a wall thickness of 25mm to make a nearly 500m-long shaft pipe by extrusion, which has been used in an offshore drilling platform. It is said that the weight of the riser pipe can be reduced by half, thereby greatly reducing the cost of ballasting. In addition, it also has high fracture toughness and long fatigue life. According to reports, in the North Sea oilfield development projects in the United States, the amount of titanium used in floating body devices and seabed fixing devices on ships has increased compared to before. The demand for titanium materials for 24 floating devices on board ships and 64 fixed devices on the seabed is: 50-100t for safety protection devices, 50-100t for connecting devices, 400-1000t for general lifting equipment, and 1400-4200t for drill pipes. The corrosion of structural parts caused by biological pollution on offshore oil exploration platforms is quite serious. A company in the United States used long casings made of titanium tubes on the mining platform to protect the parts on the platform.

The use of titanium alloy components in oil drilling and offshore production operations has increased significantly over the past few years. Titanium components allow oil drilling to go into deeper waters and deeper wells, including higher temperatures and highly corrosive (ie saline) production environments.

For such applications, TC4 titanium rod (Ti-6Al-4V) based alloy is the most suitable and the lowest cost in terms of overall performance. Seawater pipeline system is an indispensable part of subsea oil exploitation. Since titanium has high corrosion resistance to seawater, its service life is 10 times that of steel system. Therefore, the cost of titanium pipeline system is more cost-effective compared with Cu-Ni system. of. U.S. Active Metals Corporation and Precision Tube Technology Co., Ltd. jointly established a titanium tube technology company to produce a large-diameter titanium alloy tube. The alloy used for this pipe is TA18 (Ti-3Al-2.5V) alloy, with a diameter of 650mm, a wall thickness of 22-25mm, a length of 350m, and a pipe weighing 80-90t. It is planned to be used for subsea oil exploitation . Another company in the United States has used a seamless titanium alloy tube with a length of 15m, an outer diameter of 600mm, and a wall thickness of 25mm to make a nearly 500m-long shaft pipe by extrusion, which has been used in an offshore drilling platform. It is said that the weight of the riser pipe can be reduced by half, thereby greatly reducing the cost of ballasting. In addition, it also has high fracture toughness and long fatigue life.

Practice has proved that Ti-6Al-4V (Gr.5_TC4) alloy is the best material for drilling pipes. As drilling applications, yield strength and fatigue strength are the most important. Therefore, two Gr.5 alloys with special low interstitial elements are suitable For the more critical dynamic lifting device. When the service temperature exceeds 75 ~ 80 ℃, in order to prevent crevice corrosion or stress corrosion, use the Gr29 alloy containing ruthenium.

The most commonly used components include offshore drilling risers, drill pipe, tapered stress joints (TSJs) and hybrid titanium/steel risers.

Small titanium parts such as titanium pumps, valves, joints, fasteners, fixtures and spare parts have been widely used on oil exploration platforms. A large number of titanium alloys are also used in foreign offshore oil exploration well logging instruments.

There is an oxide film with a thickness of no more than 10nm on the surface of titanium. It is very stable in corrosive environments and has excellent corrosion resistance to air, seawater and marine environments. It is currently the most suitable raw material for various marine environments. Japan is vigorously developing oceans, such as the bridge from Honshu to Shikoku, the road across Tokyo Bay, Kansai Airport, and floating oil storage bases. The exposure tests conducted by the Ministry of Construction of Japan and the Iron and Steel Club on the Oigawa Ocean, and the investigation reports of various anti-corrosion exposure tests conducted by the Ministry of Transport and the Steel Pipe Pile Association on the Hasaki Sand Floating Trestle also show that titanium is the most suitable material. In addition to its excellent anti-corrosion performance, titanium also has the advantages of very few dissolved ions in seawater environment, non-toxic, and no need to worry about polluting the environment. Japan has also built a super-large floating marine structure, using titanium-steel composite materials in the seawater scour; in the construction of the Tokyo Bay across the highway, titanium materials are used as the splash-proof trunk of the bridge piers, and titanium steel is used for each bridge pier. The amount is 0.9t. Large-scale floating marine buildings that have been used or are planned include airports, harbor logistics bases, sports facilities, and so on.

The comprehensive utilization of seawater is one of the important projects in marine engineering, and the condenser of coastal power station is the equipment that utilizes a large amount of seawater. Titanium used in coastal power stations is mainly titanium used in condensers. Because the condenser uses seawater as cooling water, and seawater contains a large amount of silt, suspended matter, marine organisms and various corrosive substances, the situation is more serious in the light salt water where seawater and river water alternately change. Traditional condensers use copper alloy tubes, which are often severely damaged due to various corrosions in seawater. Titanium has good corrosion resistance in seawater, especially in polluted seawater, especially the high-speed erosion corrosion resistance of seawater.

"Water is the source of life". At present, the lack of water resources has become a problem plaguing the whole world. About 25% of the world's population does not have adequate drinking water resources. The world's terrestrial rivers and groundwater resources are far from meeting the needs of industrial development. Therefore, seawater desalination will be an effective method for human beings to solve freshwater resources in the future.

From the perspective of the development of seawater desalination at home and abroad, there are mainly two methods: distillation and reverse osmosis. In the former, seawater is heated to vaporize it, and then the steam is condensed to obtain fresh water. The latter is to pressurize the seawater so that the freshwater in it passes through a special membrane to trap the salt to obtain freshwater. Early seawater desalination devices used materials such as copper alloys and carbon steels. Because these materials were not resistant to seawater corrosion and had low production efficiency, they were quickly replaced by titanium, which has excellent seawater corrosion resistance. In seawater desalination, the main application of titanium is the heater heat transfer tube of the desalination device. The major producers of seawater desalination devices are the United States and Japan. By 2004, there were more than 15,000 seawater desalination devices built or under construction in the world, with a daily output of about 32 million tons of fresh water. A Japanese company built 10 distillation devices for Saudi Arabia with a daily output of 30,000 tons of fresh water, using 3,200 tons of titanium tubes, and an average daily output of 10,000 tons requires 107 tons of titanium.

my country's Tianjin, Shandong and other places have built or are building seawater desalination devices. For example, the preliminary plan for seawater desalination in Tianjin is to produce 500,000 tons of fresh water per day by 2007 and 700,000 tons by 2010. It is estimated that the seawater desalination projects in Tianjin and Shandong will use about 250 tons of titanium.

Titanium and its alloys are corrosion-resistant in seawater and marine atmosphere, and have light specific gravity, high strength, impact resistance, non-magnetic, sound transmission, and small expansion coefficient, so they are considered good ship materials. In recent years, the application of titanium in ships has attracted people's attention. The navies and shipbuilding industries of various countries also attach great importance to the application research of titanium on ships, and have developed many grades of marine titanium alloys. Titanium and its alloys are widely used in ships, such as hull structural parts, pressure-resistant shells of deep-sea survey ships and submarines, pipes, valves, rudders, shaft brackets, accessories, propellers and propellers in power drives Shafts, heat exchangers, coolers, hull sonar domes and more.

The first application of titanium on the hull of a ship was the α-class submarine of the former Soviet Union. Subsequently, titanium was used in artificial or unmanned deep-sea research and deep-sea assistance submarines. Industrial pure titanium is used for general structural parts, and Ti-6Al-4V alloy is used for pressure vessels. According to reports, the use of titanium for hull structures can not only reduce the weight of the hull itself, increase the effective loading weight, but also reduce maintenance and prolong the service life of the ship. Hull structural materials such as aluminum alloy and mild steel generally require maintenance in 10 years, while titanium materials hardly require maintenance and repairs, and the life span can be extended from the general 20 years to 30 to 40 years.

Japan's research on titanium alloys for deep-sea surveys has been fruitful, and almost all of the pressure-resistant chambers of the "Deep Sea 6500" that can accommodate 3 operators use titanium alloy materials. This is the result of long hours of hard work at Mitsubishi Heavy Industries Kobe Shipyard. Submarines use a large amount of titanium, for example, a nuclear submarine with a diving depth of 900m uses as much as 3500t of titanium.

According to reports, Japanese fishery has changed from fishing to fish breeding, and artificial breeding of lionfish, flounder, eel, etc. has been realized. In artificial breeding technology, a large number of titanium metal mesh and titanium tube heat exchangers to maintain a certain seawater temperature are used. The artificial culture of grouper has been realized in the coastal areas of Fujian, my country, and the titanium plate type culture basket used has brought excellent benefits to the culture of grouper.

There is huge energy in the ocean, such as tidal energy, wave energy, temperature difference energy, ocean current energy and salinity difference energy and so on. With the increasing shortage of world energy, people will be more interested in the development and utilization of marine energy. The thermal power generation and tidal power generation projects have been researched and developed. The principle of thermoelectric power generation is to use seawater with high ocean surface temperature to vaporize ammonia or freon to drive a turbine to rotate and generate electricity, and then use the low-temperature seawater in the deep ocean to cool the vaporized ammonia or freon to form a continuously circulating heat engine system.

The main equipment for thermoelectric power generation are evaporators, condensers, seawater suction pipes, loops, etc. The equipment is required not only to be corrosion-resistant, but also to be resistant to ammonia and fluorine corrosion. Titanium and its alloys not only have good seawater corrosion resistance, But also resistant to ammonia and fluorine corrosion, so titanium is the most ideal material.

 

As an emerging civil market for titanium, marine engineering has developed rapidly in recent years. With the further intensification of the world's energy crisis, countries around the world will invest a lot of manpower and material resources in the exploitation of seabed oil resources and other mineral resources; in the trend of global fresh water shortage, various coastal countries will use seawater to produce fresh water; moreover, The competition for naval equipment of various military powers is increasingly fierce, etc., all of which are inseparable from titanium and titanium alloy materials. Therefore, the application of titanium and its alloys in marine engineering will become more and more extensive. It is expected that titanium used in marine engineering is expected to become a large application market for titanium materials.