Gate Valves

A gate valve isolates flow by raising a gate or wedge clear of the bore and lowering it to seal across two parallel or tapered seats. Because the closure member moves at right angles to the flow, a fully open gate valve leaves an unobstructed full-bore path with very low head loss. Gate valves are on/off devices and are not intended for throttling: a partially open gate suffers erosion and vibration. Their strength is reliable, low-resistance isolation on lines that are opened and closed infrequently.

The two main families are the solid or flexible wedge design and the parallel slide or double-disc design. A resilient seated wedge, where the wedge is fully rubber-encapsulated, gives bubble-tight closure and is the standard choice for buried and treated water networks. A metal-seated wedge suits higher temperatures and process media. Stems are supplied as rising (the position is visible) or non-rising (favoured for buried and low-headroom installations).

Gate valves serve water distribution and buried mains, wastewater, firewater systems, oil and gas, power generation and general process pipework. Resilient seated versions dominate potable and raw water duty, while forged and cast steel gate valves handle high-pressure steam, hydrocarbons and refinery service. Surface boxes, extension spindles and gearboxes support buried and large-bore installations.

Common standards include EN 1074-2 and EN 1171 for water and industrial gate valves, API 600, API 602 and API 6D for steel and pipeline valves, with flanges to EN 1092 or ASME B16.5 and testing to EN 12266 or API 598. Bodies are typically ductile iron with fusion-bonded epoxy coating for water, or cast and forged steel and stainless steel for process duty. Trim, stem and seat materials are selected for the medium and temperature.

To specify, provide the bore, pressure rating, medium, temperature, body and trim materials, stem type and end connection. We can then confirm a suitable configuration with material and test documentation for the application.