Figure 1. Cast steel rising stem gate valve with flanged ends

Main Types of Gate Valves (Gate Valve Classification)

Gate valves are usually classified by stem design, gate (disc) design, bonnet construction and end connection. Understanding each classification helps you match the valve to the duty.

Rising Stem vs Non-Rising Stem

Rising stem (OS&Y - outside screw and yoke) - the stem threads sit outside the valve body, and the stem rises visibly through the yoke as the valve opens. This gives clear visual indication of the open or closed position and keeps the threads away from the process fluid. Rising stem valves need vertical clearance, so they are the standard choice for above-ground installations, fire protection systems and large industrial lines.

Non-rising stem (NRS) - the stem threads are inside the valve, and the overall height stays constant during operation; a small pointer indicator shows the valve position. Because the threads are in contact with the media, NRS valves suit clean fluids and are widely used underground and in areas with limited vertical space.

Wedge Gate vs Parallel Slide Gate

Wedge gate - the gate is wedge-shaped and seals against inclined seats. Solid wedge gates are a single rigid piece: simple, economical and ideal for clean, moderate service. Flexible wedge gates carry a slot that lets the two sealing faces flex, compensating for thermal expansion and pipe stress and resisting binding. Split wedge gates are made of two pieces that self-adjust to the seats, giving a reliable seal in demanding conditions.

Parallel slide gate - the gate is pushed flat against parallel seats, often as a double disc with spreaders. This design avoids binding under thermal cycling and is widely used for water and sewage service and large oil and gas pipelines.

Bonnet Design: Bolted, Welded, Pressure-Seal

Bolted bonnet - the most common design; the bonnet is bolted to the body for easy maintenance and repair.

Welded bonnet - the bonnet is welded to the body, giving a compact, leak-free construction for low-maintenance service.

Pressure-seal bonnet - the bonnet seal is tightened by line pressure, making it the preferred choice for high-pressure and high-temperature service.

End Connections and Operators

Gate valves are available with threaded, socket-weld, flanged and butt-weld ends. Flanged valves dominate process and pipeline service, while welded ends suit high-pressure, large-bore lines. Operators range from a simple handwheel to gear operators on large valves and electric or pneumatic actuators for automated systems.

Table 1. Gate Valve Types at a Glance

Type	Key Feature	Best For
Rising stem (OS&Y)	Stem rises visibly; threads outside the body	Above-ground lines, fire protection, visual status
Non-rising stem (NRS)	Constant height; threads inside the body	Underground and low-headroom installations
Solid wedge gate	One-piece rigid gate	Clean, moderate service
Flexible wedge gate	Slotted gate resists binding	Thermal cycling, pipe stress
Split wedge gate	Two-piece self-adjusting gate	Demanding sealing conditions
Parallel slide gate	Double disc with spreaders	Water, sewage, large pipelines

Figure 2. Rising stem (OS&Y) and non-rising stem gate valve designs

How to Choose a Quality Gate Valve: 7-Point Checklist

Once you know which type you need, use this checklist to judge the quality of the valve and the supplier.

1. Match the body material to the media. Cast iron suits water and wastewater; carbon steel (A216 WCB) handles general oil, gas and steam service up to about 425 °C; alloy steel (A217 WC6/WC9) covers high-temperature duty; stainless steel (A351 CF8/CF8M) resists corrosive and hygienic media; LCB grades serve low-temperature service.

2. Confirm the pressure class and temperature range. Check the ANSI Class (150, 300, 600, 900, 1500 or 2500) or the applicable JIS/DIN rating, and make sure the body, seat and stem materials cover your process conditions.

3. Choose the right stem design. Use a rising stem (OS&Y) where visual position indication matters or threads must stay dry; use a non-rising stem where headroom is limited or the valve is buried.

4. Select the gate design for the duty. Solid wedge for clean general service; flexible or split wedge where thermal cycling or pipe stress may cause binding; parallel slide for water and sewage systems.

5. Verify standards compliance. Ask for valves designed to API 600 (cast steel), API 603 (stainless steel), API 602 (forged small bore) or API 6D (pipeline), and tested to API 598.

6. Check the bonnet, packing and trim. Choose bolted, welded or pressure-seal bonnets by service; check the gland packing material (e.g. graphite or PTFE), and confirm the stem and seat faces are hardened - typically 13Cr stainless or Stellite-faced - for wear resistance.

7. Audit the manufacturer. Check traceable material certificates, hydrostatic and pneumatic test records, a reliable quality system and responsive after-sales support.

Figure 3. Quality check: measuring the gate disc with a caliper

Gate Valve FAQ

Q1. What is the difference between a rising stem and a non-rising stem gate valve?

In a rising stem (OS&Y) valve, the stem rises visibly above the handwheel, giving clear open and closed indication and keeping the threads away from the fluid. In a non-rising stem valve, the stem stays at a constant height and the threads work inside the body, which suits underground and low-headroom installations.

Q2. Can a gate valve be used for throttling?

No. Gate valves are designed for fully open or fully closed isolation. Partial opening leaves the gate and seats exposed to flow, which can cause vibration, erosion and damage. Use a globe valve or V-port ball valve for throttling.

Q3. What materials are gate valves made of?

Common body materials are cast iron, carbon steel (WCB), alloy steel (WC6/WC9) and stainless steel (CF8/CF8M). The stem and seat surfaces are typically hardened with 13Cr stainless steel or Stellite facing for long service life.

Why Choose Sunrise as Your Gate Valve Supplier

XIAMEN SUNRISE IMP&EXP CO., LTD is a professional one-stop oil pipeline spare parts supplier. Our main products include valves, pipes, pipe flanges, pipe fittings, plates, fasteners and gaskets. With integrated R&D, manufacturing and export services, we supply both conventional and customized products with professional support at every stage. For a quotation or technical advice on gate valves, contact us at Janisa@xiruicn.com or +86 139-5012-2117.

SEO Notes for Publishing (Editorial Use Only - Do Not Publish This Page)

Meta Title (<= 60 chars):

Gate Valve Types & Selection Guide: How to Choose Quality Valves

Meta Description (~155 chars):

Learn the main gate valve types - rising stem vs non-rising stem, solid wedge vs flexible wedge - and how to choose a quality gate valve for your piping system.

Primary Keywords:

gate valve types; gate valve selection guide; how to choose a gate valve

Secondary Keywords:

rising stem gate valve; non-rising stem gate valve; OS&Y gate valve; solid wedge gate valve; flexible wedge gate valve; parallel slide gate valve; flanged gate valve; stainless steel gate valve; API 600 gate valve

Suggested URL Slug:

/blog/gate-valve-types-and-selection-guide

Suggested Category:

Product knowledge

Image Alt Text 1:

Cast steel rising stem gate valve with flanged ends from Sunrise

Image Alt Text 2:

Gate valve types: rising stem OS&Y and non-rising stem gate valves

Image Alt Text 3:

Gate valve quality inspection: measuring the wedge gate with a caliper

Internal Links:

Link to existing posts on this blog, including "Ball Valve: Complete Guide to Types, Working Principle, Materials & Selection", "Ball Valve Principle, Explained in 90°" and the ball valve types and selection guide article.