IsoTech® ValvTechnologies parallel slide gate (PSG) seat-protected valves are the culmination of years of practical design enhancements and eliminating the limitations of typically accepted norms in gate valve design.
Proven precisely right for steam and feed water isolation applications IsoTech® valves offer our rigorous four-year zero-leakage guarantee for steam and water applications and low-cost maintainability. IsoTech® valves exceptional durability is in large part due to the use of our HVOF RiTech® hard coatings with a RC 70 seat hardness and are designed for up to ASME/ANSI Class 4500 at 1800°F (982°C).
IsoTech®, ValvTechnologies’ PSG valve addresses the need for true in line valve repairability in large diameter, high energy piping systems. Specifically designed for steam and feedwater applications, IsoTech® provides bi-directional, zero-leakage using our exclusive HVOF RiTech® process.
1. Bonnet area. The pressure seal bonnet has been designed with a graphite composite seal. The bonnet has sufficient mechanical bolting to ensure the seal does not relax during periods when the system is not pressurized. In addition to the high reliability of the seal, the bonnet area has been designed to minimize the problems associated with maintenance on large gate valves. The valve has been designed so that the bonnet does not have to be forced in to the valve bonnet throat to allow for the segment rings to be removed. The large bolting used to ensure that the pressure seal is always loaded has also been utilized to enable simple dissassembly of the bonnet once the easy to extract segment rings have been removed.
2. Gland area. The gland is the same standard design employed throughout ValvTechnologies’ various valve product lines. The stem and gland are hardfaced and polished. The packing has 316 SS woven wire mesh anti-extrusion rings top and bottom and grafoil center ring. This is combined with our proven, superior, multiple Belleville® spring stacks, live loaded stuffing box. The gland design completes the superb proven pedigree of this valve range.
3. Disc and seat area. The valve discs and seats have been overlaid with the same carbide overlay (68-70 RC) as its counterpart, the ValvTechnologies’ metal seated ball valve. These seats are several magnitudes harder than Stellite 6, typically (34-38 RC) and are lapped to achieve a bubble-tight seal under all pressure conditions, including vacuum. The large spring load ensures a high initial seal, and the line pressure increases the sealing. The web guide (which is also carbide overlayed) ensures the discs are kept parallel, whether the valve is in the open or closed position. This overcomes a common gate valve problem. As the valve is cycled under differential pressure, the extremely hard surfaces continually hone and polish each other instead of scratching and galling. The seal is improved rather than degraded with wear/use.
4. Back seat area. The back seat is coated with chrome carbide (typical hardness 68-70 RC) and polished to achieve a bubble tight seal.