The standard of titanium elbows first appeared in the American aerospace standard, and the only international standard for titanium elbows in the chemical industry is ASTM B363 [5].

ASTM B363 was established in 1961. It was first modified in 1978. After that, it was modified many times (such as 83, 87).

In 1994, by the northwest institute of non-ferrous metals issued the enterprise standard Q/XB1507-94 “titanium butt welded seamless pipe fittings”.

This standard represents the beginning of the standardization of titanium elbows in China. This is China’s titanium pipe production, distribution, design, construction of the main reference documents.

In order to make the standard to better guide China’s titanium pipe standardization production, design, selection, procurement, distribution, installation, construction, national petroleum, and chemical industry bureau issued on July 13, 1999, by the titanium seamless pipe butt welding industry standard, this standard drafted by right of the northwest nonferrous metal research institute, the standard of HG/T3651-1999, June 1, 2000, in the implementation.

The standards stipulated by the pipe size tolerance with the national standard ANSI B16.9-1986 “forged steel welded with pipe fittings” and China’s national standard GB 12459-90 “steel seamless pipe butt welding, the fitting of requirements and the surface quality of the finished pipe material and pipe fittings with the American society of testing materials standard ASTM B363-95” seamless and butt welding seam titanium and titanium alloy with elbows “.