Industrial Gate Valves

Full-bore isolation valves for water networks, steam mains and industrial pipelines. Rubber-seated, wedge gate and OS&Y designs. DN 40 to DN 600.

What are gate valves?

Gate valves are multi-turn linear-motion valves in which a gate (disc or wedge) is raised completely out of the flow path when open, providing a full-bore, unobstructed passage with minimal pressure drop. Closing requires multiple turns of the handwheel, which gradually lowers the gate across the pipe bore until it seats against the valve body. This slow operation is deliberate — it prevents the sudden pressure changes that cause water hammer in large pipelines.

There are two principal designs: resilient-seat (rubber-seated) gate valves, where the entire gate is encapsulated in a flexible elastomer (EPDM), and metal-seated wedge gate valves, where the gate is solid metal and seats against machined metal body rings. Resilient-seat valves dominate water utility and municipal applications for their tight shut-off and resistance to grit and debris; metal-seated valves are required for high-temperature and high-pressure service where elastomers would degrade.

Roffia stocks gate valves for a wide range of applications — from resilient-seat ductile iron valves for water distribution networks (supplied with drilling for integrating with valve keys and valve boxes) to high-pressure, high-temperature forged steel gate valves for steam and petrochemical process service.

Gate valves — Roffia srl

Resilient seat gate valves

  • Body: ductile iron GGG40, epoxy-coated
  • Gate: EPDM-encapsulated, full-bore
  • DN 40–600, PN 10–16
  • Flanged to EN 1092-1
  • NRS or OS&Y versions
  • Potable water approval (WRAS, KTW)

Wedge gate valves (cast)

  • Body: cast iron GG25, bronze seats
  • Body: ductile iron GGG40, SS seats
  • DN 50–600, PN 16–25
  • Flanged to EN 1092 or ANSI B16.1
  • Steam to 250 °C, water, industrial fluids
  • Rising stem (OS&Y) standard

Forged steel gate valves

  • Body: carbon steel A105, SS 316
  • DN 15–80, ANSI Class 150–2500
  • SW, BW, screwed and flanged ends
  • High-pressure steam, oil & gas, HPU
  • Full and reduced bore options
  • API 600 / BS 1414 design

Application sectors

Water utilities and fire protection

Resilient-seat gate valves are the standard isolation valve for municipal potable water distribution, wastewater treatment plants, pumping stations and fire protection mains. Their full-bore, debris-tolerant design makes them ideal for buried service with valve boxes, or for large-diameter above-ground pump isolations.

Steam and industrial process

Metal-seated and forged steel gate valves are used for steam isolation at boiler outlets, steam distribution headers and turbine inlet lines. Their multi-turn design prevents the water hammer that a quick-closing ball valve would cause in large steam mains. See also: choosing valves for steam systems.

Oil & Gas and petrochemical

Forged carbon and stainless steel gate valves designed to API 600 and API 602 are used in oil & gas process trains for isolation of crude oil, refined products, natural gas and associated process fluids at high pressures (ANSI Class 300–2500). NACE MR0175 trim available for sour service.

Industrial utilities and HVAC

Cast iron and ductile iron gate valves remain a cost-effective isolation solution for industrial plant utilities — compressed air headers, cooling water circuits, and heating hot water systems — where their full-bore design keeps pressure drop to a minimum on long distribution lines with multiple branches.

Frequently asked questions

What is the difference between a gate valve and a ball valve?
Both gate and ball valves are designed primarily for full-bore isolation, but they differ significantly in design, speed of operation and application. A gate valve opens and closes by moving a wedge or parallel gate element perpendicular to the flow axis using a threaded stem and handwheel. Full opening requires multiple turns of the handwheel and is generally slow — but the slow operation is a feature in high-pressure water systems, as it prevents water hammer. A ball valve opens with a single quarter-turn and is much faster to operate. Gate valves are preferred in large-diameter water networks, steam mains and industrial pipelines where space is adequate and speed of operation is not critical; they also handle high pressures and temperatures very well. Ball valves are preferred where fast operation, compact installation or frequent cycling is required.
Can gate valves be used for flow regulation (throttling)?
Gate valves are not recommended for throttling. When partially open, the gate is exposed to the high-velocity flow which causes vibration of the gate and progressive wire-drawing erosion of the seat faces, leading to premature leakage. Gate valves should only be operated in the fully open or fully closed position. For flow regulation in steam or water systems, globe valves, control valves or needle valves — which are specifically designed for throttling — should be used. The exception is large-diameter, low-velocity water systems (irrigation, raw-water intakes) where partial opening at low pressure drop may be acceptable as a temporary measure.
What is the difference between rubber-seated and metal-seated gate valves?
Rubber-seated (resilient seat) gate valves have a gate element fully vulcanised in rubber (EPDM or NBR), which provides a perfect shut-off (Class A to EN 1074) even against solid particles in the water — the rubber deforms slightly to encapsulate any debris at closure. They are the preferred choice for potable water networks, wastewater, irrigation and fire-fighting mains. Maximum temperature is typically 70–80 °C for EPDM versions. Metal-seated gate valves (wedge gate valves) have bronze or stainless steel clad seat rings and a metal gate. They can handle higher temperatures (up to 450 °C in carbon steel versions) and pressures (PN 25–100 or ANSI Class 300–2500), and are specified for steam, thermal oil, hot water above 80 °C and industrial process fluids where rubber seats would degrade.
What sizes and pressure ratings are available for gate valves?
Gate valves are available in an extremely wide range. Resilient seat gate valves are typically available from DN 40 to DN 600 with flanged connections to EN 1092-1, PN 10 or PN 16, and are the backbone of water utility networks. Metal-seated (wedge gate) valves cover DN 15 to DN 600 in cast iron GG25/GGG40 (PN 10–25), and from DN 15 to DN 300 in carbon steel (PN 25–100) and stainless steel (PN 16–100). Forged steel gate valves (socket-weld and butt-weld ends, flanged and threaded) are available in small sizes (DN 15–80) for high-pressure steam applications to ANSI Class 600 and 900. Roffia stocks the most common sizes and specs for immediate delivery.
When should I specify a rising-stem versus a non-rising-stem gate valve?
In a rising-stem (OS&Y — outside screw and yoke) gate valve, the stem rises visibly above the handwheel when the valve is open, providing an immediate visual indication of valve position. This design is preferred for above-ground installations, steam systems, process plants and safety-critical applications where operators need to confirm valve status at a glance. In a non-rising-stem (NRS) gate valve, the stem does not project when the valve opens — the gate travels along an internal thread on the stem. NRS valves are used in underground installations (water mains buried in the ground), compact valve chambers and situations where headroom is limited. Both designs are available in Roffia's catalogue; resilient-seated gate valves for water utility service are almost always NRS to facilitate underground installation with valve boxes.

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