Bolt cover,PLUG  90 degree around.
Its sealing is realized by the sealing face around the sleeve.It has unique 360 degree metal edge for protection and fixing of the sleeve.There is no cavity in the valve for accumulation of medium.Metal edge provides the function of self-cleaning when the PLUG  is rotated,applicable to the operation condition thatis glutinous and apt to smudge.Double direction.Standards Related Products of :
compliance
Design and Manufacture: API 599,API 6D
Face to face(end to end): ANSI B 16.10
Flanged connection: ANSI B16.5
Test and inspection: API 598,API 6D