BALL VALVE TOP ENTRY

[trixvalve]

Could someone explain me why to specify a ball valve top entry? Which is the technical advantages? On which application do you suggest to specify this kind of valve?

 

[JLSeagull]

Top entry permits maintenance on the ball valve without removing the valve from the pipeline. Two piece and three piece valves are maintainable but the valve must be removed from the pipe. Welded body valves require shop service.

 

[JimCasey]

JLS is right.
Also, when the seats are tapered, they compensate for wear and thermal effects, and the differential area at the top and bottom of the ball with tapered seats loads the ball into the seats for better sealing at higher pressures.

In extreme applications the top-entry bonnet, stem, ball, seats, seals, can all be assembled into a carrier, or cartridge. A cartridge-loaded valve is really close to an instantly repairable valve. Pull out the bonnet bolts, snatch out the cartridge, drop in a new cartridge, and bolt 'er back down. Then you're up and running again. This is very handy when the maintenance personnel have to limit their time in proximity to the valve due to heat, toxicity, radiation, or being deeply submerged.

 

[gerhardl]

OK, just to add a small correction on three-pieces ball valves: some smaller three-piece ball valves has a mid section containing the ball, section kept in place by (usually) 4 outside connecting bolts between the two end parts.

By this construction you can take out three bolts and swing out, change or maintain the ball and seals, with welded or flanged end pieces connected.

Limitid usually/normally to 64 bars and 4 inch. For larger, tougher or higer pressures: refer to answers above.