The ValvTechnologies NexTech® trunnion valve is an low pressure (Class 300-900) bi-directional split-body valve with a trunnion supported ball and floating seat. The evolution of metal-seated isolation valves took a leap forward with the ValvTechnologies’ introduction of this NexTech® trunnion valve for the API 6D market.
With the NexTech® design, ValvTechnologies has produced a high-performance valve using our advanced carbide seating technology but in a package better suited for automated, high-cycle, and high-speed service. The NexTech® design successfully meets Class V AND VI (or better) seat sealing with extended service life in severe service conditions, as well as handles extreme thermal stress.
Features include tungsten carbide coated seats and ball, easily adjustable live-loaded Grafoil®/Inconel stem packing, low-torque body-supported trunnion bearing design, Grafoil® seat seals with Belleville pre-load springs and special internal configuration for solids and polymer service. The NexTech®’s four-bolt live-loaded gland packing system meets ISO 15848 and TA Luft emission requirements.
We utilize a split-body design which allows the actuator to be mounted on the body itself which is much better suited to accept the load. This design eliminates an additional seal which can fail and result in a leak to the environment.
Fire tested, graphite seal design
Double seal in design: In the NexTech® valve, the seats on each side of the valve have double Grafoil® seals to prevent leaks and double the run life of the valve. The NexTech® utilizes our HVOF RiTech™ tungsten carbide coatings on the ball and seats. This coating is eight times harder than Stellite and will prevent damage caused by hard solids such as catalyst, metal flakes, salt deposits, etc. The NexTech® trunnion valve maintains contact between seat and ball resulting in a self-cleaning effect. The R series offers Class V sealing while the E series provides Class VI, per ATT, shut-off sealing at the time of shop testing,
The gland springs, consisting of six Bellville springs per stud, are designed to apply a constant load hence the term “live loaded packing”. The gland springs apply a calculated load on the packing to prevent leaks that result from normal wear of the Grafoil® packing and or temperature cycles that could occur.
Male stem to ball engagement: the ball top is a “female” connection with external bearings around the ball to accept the loads from the pressure differential in the system. The results in much lower stress on the packing and reduced emissions.
An advantage of the ValvTechnologies’ NexTech® design is the use of a four-stud, live-loaded, gland packing system. This system has been proven and tested to meet all international standards. This engineered packing system is composed of a Chesterton five-ring Grafoil® packing set held with constant pressure from the four studs containing six Bellville springs each. This holds correct pressure on the packing to prevent leaks through all valve temperature changes and wear of the Grafoil® packing. The NexTech®’s live-loaded packing design allows for routine adjustments to the packing set in order to prevent or stop potential leaks. The packing system achieves a Class “B” rating under ISO 15848. ValvTechnologies offers a field warranty on sealing performance versus a warranty only good at time of shop testing.
The ball of the valve is a high-strength alloy with a diamond lapping of chrome carbide a HVOF RiTech™ hardcoating (66-69 RC hardness) to ensure bubble tight shut-off.
The Belleville spring (spring for seats) features a high-spring load that ensures good contact, not only between the ball and seat, but also at all positions from opened to closed. The high-spring load allows for zero-leakage at hydrogen on vacuum and ensures contact throughout the stroke of the valve, preventing particulates from migrating between the ball and seat.
The integral seat is machined into the end cap, eliminating the potential for leaks between a loose seat and the valve body.
A precisely engineered and machined component that locates and stabilizes the ball