In recent years, the application of titanium and titanium alloy piping in seawater has become one of the important directions of ship development. It is expected to promote the application of titanium alloy better based on the following introduce on the application technology of titanium and titanium alloy piping in sea water. At present, foreign countries such as the United States and Russia have started to use titanium alloy in seawater pipeline system, and some domestic small ships have also started to use titanium alloy system, and these applications have achieved good results.

1. Application at abroad

Russia is the country with the highest application of titanium alloy on ships in the world. In the 1960s ~ 1980s, titanium alloy was widely used in ships, and titanium alloy pipes were used in almost all subarines. In the 1970s, the "Poisonous spider" class missile boat developed and produced by the former Soviet Union used a lot of titanium alloy in seawater piping. It is still being fitted in many countries.

In 1990, the U.S. Navy established an onshore pipeline testing site to test titanium alloy pipelines, including the effects of different flow rates on Arine life. Subsequently, the SAN Antonio-class amphibious transport ship (LPD17) adopted titanium alloy in two main seawater piping systems (ballast water and fire protection system). Both systems were completed in the shipyard, including more than 1000 pipe fittings and titanium pipes with a total length of more than 3300 m. The titanium tube, with a maximum diameter of 12 inches, is a milestone application of the titanium alloy in U.S. ships. The ship's superstructure is designed to reduce piping system quality by 50%, which is greatly improving the ship's stability. Although the initial investment is higher than the copper-Nickel system, the cost savings over the whole life period are nearly $17 million.

In addition, the United States also USES titanium and titanium alloy in DDG51, CG47, LHA2 and other types of seawater piping systems.

2. Domestic application

China began to study the ship titanium alloy in the 1960s, and through many years of research and development, the ship titanium alloy material system has been preliminarily established. Around 2003, the fire-fighting system, main and auxiliary seawater cooling system, air conditioning cooling system and pipes, fittings, flanges and valves of the seawater piping system of a certain type of boat were all made of pure titanium, which was also the first time that titanium was used in the seawater piping system in China. So far, these materials have achieved good service effect without leakage, corrosion failure and other problems. The tensile strength of the pipes in service has been reinspected, and no performance attenuation has been observed.

Domestic manufacturers and research units have also carried out product research on pure titanium, TA24, TA36 and other ship titanium alloy pipes according to the requirements of Arine sea water pipelines, and carried out evaluation and test on the developed products. In order to fully master the application technology of titanium alloy in Arine sea water pipeline system, domestic ship overall design Institute, 725 institute and other units have built a number of titanium alloy test platforms to conduct systematic assessment on the application technology of titanium alloy such as material compatibility, sealing pressure, corrosion protection and Arine biological fouling prevention.

Although titanium alloy's corrosion resistance and other advantages make it show good service performance in seawater pipelines, due to the relatively weak industrial foundation in China and the late development of relevant research, the accumulation of relevant data still cannot meet the requirements of system safety and reliability for ship application. Therefore, the application of titanium alloy in arine pipeline is still limited to a small range. In recent years, with the development of China's navy construction, the application of titanium alloy in seawater pipeline has been put on the agenda, and its research has been strengthened constantly.