As another assembling way of ball valve stem, top entry ball valves are valves that assembled its ball from top side part. It usually made from casting metal.
Commonly, casting metal is used for the construction of the top entry valve. Since it is made by casting, some additional NDE testing is required to remove the defects of the casting process.
It is a type of ball valve that assembles the ball from its top side part. This design allows the seats and ball to be maintained without valve removal from the pipeline. It is best suitable for large systems. You can also clean it without removing it from the pipeline.
Top Entry Ball Valve Assembly Drawing
The top entry ball valve standard configuration is soft seated trunnion mounted with self-relieving seats, anti-blowout stem, antistatic device, fire-safe certified. To comply with technical requests, they can be provided with particular features as double block and bleed, double piston effect construction, stem extensions, secondary tightness injection fittings, metal seats, transition pieces and/or pup pieces, special face to face dimensions and bore sizes (piggable), PTFE spring energized lip seals in case of cryogenic applications or hazardous fluids.
These valves have complete flexibility in the use of materials for body and trim along with seal gasket selection. For this reason, they are suitable for the most severe applications which can be encountered onshore, offshore and in the process industry.
3. Marerial Applications
The bonnet-body construction allows the use of different grades of carbon steel, stainless steel and exotic alloys thus complying with the most severe service conditions.
Advantages & Benefits:
1.Self-Adjusting Seats: Compensate for Wear & Temperature Fluctuations
2.Spring Loaded Low Pressure Seals
3.Pressure Activated Seating
4.Built-In Antistatic Feature
5.Simplified In-line maintenance/reparability
Oil and Gas Product Pipelines and Transmissions, Gas Storage, Onshore and Offshore Platforms, Liquid Gas Launch and Receiving Stations, Power Plants, Compressor Stations and Measuring Skids, Dehydration, Dryer, Gas Separation Systems.
Top Entry Ball Valves vs. Side Entry Ball Valves
The ball valve can be divided into side-mounted ball valve and top-entry ball valve according to the assembly method. Now let’s compare them.
1. These ball valve concepts refer to the manner in which the valve ball and its internal components may be reached, either from the side of the valve or from the top of the valve (top entry).
2. The top entry design is used when repeated inline maintenance operations are required on the valve. This is due to the fact that the top entry ball valves provide quicker and faster access to the ball and valve trim relative to the side entry valves that need more repair time and space for the same operations.
3. The top entry ball valve is assembled from top. The biggest difference from the side entry ball valve is that top entry ball valves do not need to be removed from the pipe in maintenance. Plus, the less bolted connection brings less leakage paths and lower weight compared to three-piece side entry ball valve.
The Two Ball Valve design Can Be Distinguished As Follows
1. Top entry ball valves are normally manufactured with cast steel bodies; while side ball entry valves are constructed with (strong) fabricated steel bodies.
2. Top entry ball valves are one piece ball valves. Side entry valves are two-piece ball valve or three-piece ball valve.
3. Top entry ball valves need more non-destructive testing than side entry ball valve due to their castings; side entry valves are simpler to install and assemble than the top entry, which takes a long time of training and workmanship to function properly
4. Top entrance ball valves are usually more costly than side entrance valves and have longer lead times attributed to the casting operations used to produce the body.
The Top entry ball valve is mainly used when frequent maintenance is required for the valve and the seat, it provides ease of access for maintenance and repairs as the ball and the seat inside the valve can be maintained from the top of the valve and without dismantling the whole valve from the pipeline.