... Q345,16Mn Surface treatment:coated black ,even other color double heads with cap small dia pipe Seamless steel pipe/seamless pipe/steel tube(1)Surface ... treatment:coated black, anti-rust varnish, anti-rust ... -5L,API5CT,GB/T8163,GB/T8162.(3)Steel grade:Q235,Q345,STEEL ROUND PIPE SIZE-OD IN INCH N MM MATCH ...