A Trunnion ball valve has mechanical anchoring of the ball

A Trunnion ball valve has mechanical anchoring of the ball at the top and the bottom, suitablf ro larger and higher pressure services. To ensure tight sealing at low pressure, high tensile springs force the seats against the ball while at higher pressure, the medium pressure pushes the upstream seat towards the ball.
For trunnion mounted Ball valves size NPS 6 (ND 150) and above, it comes with provisions for sealant injection on both the stem and seat while for sizes NPS 5 (DN 125) and below on body cavity. In case of failed underperformed seals, a temporary emergency seal can be achieved by injecting sealants.