Floating ball valve of the structure

2013-11-18


Floating ball valve by valve structure can be divided into side-mounted valve body and coat type two categories. Side-mounted valve can be divided into the overall style, two and three- piece . Whatever the structure, they must meet some basic principles.
① stem should flip, blow out proof structure . This is the first ANSI B16.34 the provisions of Section 6.5.1.1 , the structure of its valve stem packing gland should not depend on the position of the fastener to limit it , to be precise , the valve pressure state, the stem will not stem seal due to loosening of fasteners and off valves. It is safe to use from the valve angle must ensure the basic conditions.
② anti-static structure is composed of a stainless steel ball and a spring composed of a group into stem end of the hole , keeping in contact with the ball ; another group placed on the stem of the cylinder to maintain contact with the body , so that the electrostatic potential lead away from the body .
③ fire safety (fire-safe) structural design, primary and secondary valve seat when the PTFE sealing plastic burning due to fire , should be in contact with the ball , and maintain a certain degree of sealing ; primary and secondary valve connection surface should be used with fire safety function pads, such as metal spiral woundgasket ; stem packing seal in place, when the filler (PTFE) is burning , there should be a graphite ring to prevent the media leaked out .