Material selection plays a key role in gate valve performance

Wedge Gate Valves

Wedge gate valves are used to shut off flows of low-viscosity media (water, steam, gas, petroleum products) in main and process pipelines.

They are not intended for flow regulation or operation with abrasive media.

Key Materials and Standards

Body and Bonnet

The primary material for most media (water, steam, oil, gas).
Main standard – GOST 33260-2015 (GOST 977-89).
This standard regulates steel grades (for example 25L, 35L cast steel) and their mechanical properties (strength, impact toughness) depending on pressure and temperature.

Why this matters

For example, steel 25L provides sufficient strength for operation at pressures up to 100 MPa and temperatures up to +425°C, covering most industrial needs.

For higher temperatures or aggressive environments, alloyed steels containing chromium, molybdenum and nickel are used (for example 20ХМЛ, 09Г2С).

For water, steam and gas at low pressures and temperatures (up to +175°C):
Main standard – GOST 7293-85 for cast iron (grades SCh20, SCh25).

The use of cast iron for high-pressure steam is prohibited due to brittleness, as specified in operating regulations.

To ensure tightness, wedge and seat surfaces are often hard-faced with corrosion- and wear-resistant alloys.

GOST 10049-93 (or the newer GOST R ISO 18274-2022) – welding wires and rods made of stainless alloys.
Hard-facing, for example chromium-nickel alloys, prevents corrosion and erosion of sealing surfaces and maintains tightness throughout service life.

GOST 5152-84 – sealing materials (asbestos cords, paronite).
Today asbestos-free materials are more commonly used, but the standard defines basic thermal and chemical resistance requirements.

Knife Gate Valves

Knife gate valves are designed for viscous, contaminated and abrasive media (slurry, pulp, wastewater).

The main emphasis here is wear resistance.

Key Materials and Standards

Body and Bonnet

Cast iron – GOST 7293-85 (grey iron) or GOST 26358-84 (ductile iron) for non-aggressive media.

Carbon steel – GOST 33260-2015 (GOST 977-89) for higher pressures or abrasive media.

Stainless steel – GOST 5632-2014
Grades 12Х18Н10Т, 08Х13, 20Х13 are used for components operating in aggressive environments.
Steel 12Х18Н10Т has high corrosion resistance in oxidizing environments, critical for chemical and food industries.

Gate (Blade/Knife)

This is the main working element – it must be hard, sharp and wear-resistant.

Stainless steel – GOST 5632-2014 (grades 30Х13, 40Х13 hardened to high hardness)

Tool steel – for the most severe abrasive conditions

Superhard coatings (for example tungsten carbide) are often applied (standards typically referenced in GOST R ISO 18274-2022)

Seals

Wear-resistant elastomers are critical:

Rubber seals – GOST 7338-90
Example: IRP-1347 (oil- and fuel-resistant) or IRP-1118 (food-grade media)

Incorrect rubber selection in oil environments causes swelling and destruction, leading to leakage.

Steel Butterfly Valves

Butterfly valves have a simple design and are used to shut off and regulate liquids and gases in large-diameter pipelines at moderate pressures.

Key Materials and Standards

Body (Steel)
Main standard – GOST 33260-2015 (GOST 977-89)
Cast from carbon (25L) or alloy steels

Disc
Manufactured from the same steel as the body or stainless steel (GOST 5632-2014) to improve corrosion resistance
Often coated with anti-corrosion materials (rubber, epoxy)

Seat Ring

The critical component that ensures tightness between disc and body.

Rubber seals – GOST 7338-90
Most common: EPDM (water resistant), NBR (oil resistant)

PTFE – GOST 10007-80
Used for aggressive media (acids, alkalis)

An EPDM seat ensures sealing in water pipelines but quickly degrades in gasoline pipelines where NBR is required.
The seat material directly determines the application area of the valve.

Conclusion

Material selection for pipeline valves is not simply choosing a metal — it is a complex engineering task based on three factors:

Working medium – Pressure/Temperature – Material

Compliance with standards provides:

• Cost savings – prevention of premature failures and expensive repairs
• Technical predictability – assurance the valve reaches its calculated service life