[国外标准] BS EN 10253-4-2008 Butt-welding pipe fittings. Wrought austenitic and austenitic-ferritic (duplex) s
[国外标准] BS EN 10253-2-2007 Butt-welding pipe fittings. Non alloy ferritic alloy steels with specific inspect
[国外标准] BS EN 10253-1-1999 Butt-welding pipe fittings Part 1 Wrought carbon steel for general use and withou