Inlet valves
Gas exchange valves for the inlet side

Exhaust valves
Gas exchange valves for the outlet side

Start valves
For starting large engines with compressed-air

Constant throttle valves

IEC designs and manufactures all types of valves that are used in combustion engines.

Monometallic and bimetallic valves

Especially heavy-loaded exhaust valves are often made of two different materials. The valve disk is made of a heat-resistant steel or a nickel-based superalloy to withstand the high thermal loads. Since such materials are generally not hard, a different material is used on the shaft. This is usually a magnetic steel that is hardened inductively at the shaft end to minimize wear.
The two materials are joined by friction welding.

1.4718 – X45CrSi9-3 – HNV3
Typical stainless martensitic valve steel with excellent nitriding hardenability. Generally used for low-loaded inlet valves or for valve stems.

1.4871 – X53CrMnNiN21-9 – EV8
Typical austenitic valve steel with added nitrogen for increased resistance at high temperatures. Frequent use with exhaust valves for operating temperatures up to 800°C.

1.4882 – X50CrMnNiNbN21-9
Austenitic nickel-chromium-manganese steel with added Nb and W. It offers high mechanical strength at high temperatures. Used for exhaust valves of heavy-loaded engines.

2.4952 – NiCr20TiAl – HEV5
Also known as “Nimonic 80A”. Classic nickel-chromium superalloy with perfect resistance to oxidation and corrosion. High wear resistance and very good tensile strength. NiCr20TiAl is used in heavy-loaded engines. Both for high loads in motorsports, as well as for special requirements from corrosive gases such as biogas, landfill gas or sewer gas. This material is also frequently used in marine applications.

3.7165 – TiAl6V4
Titanium alloy for inlet valves. It is characterized by a very low weight and is therefore the first choice for high-speed engines.

Valve seat

As a protection against wear, in the seat area we use materials with special properties, such as a high level of hardness, good resistance against hot gas corrosion or the like.

Most of these materials are applied by plasma arc welding.

However, there are many other armour technologies that can be used for all types of armour materials: Laser cladding, TIG, HVOF, etc.

On the valve seat, we also use modern nitriding processes. The nitrided valve seat, in combination with special materials used for the seat ring, provides a long service life, as it is the case in gas engines.

Common armour materials:

Stellite 1
Cobalt-based material with the incredible wear properties and high corrosion resistance.

Stellite 3
Cobalt-based material with a high proportion of tungsten. Outstanding wear and corrosion resistance at high temperatures.

Stellite 6
Common cobalt-based armour material. Good wear and corrosion resistance.

Stellite 12
Cobalt-based material with high temperature resistance and good corrosion resistance, for example against salty air.

Stellite F
Cobalt-based material with a high nickel content.

Colmonoy 56
Nickel-based material with hard chromium borides.

Tribaloy T-400
Cobalt-based material with outstanding properties in terms of wear and corrosion resistance.

Iron-based hard facing
IEC offers various types of seat armouring with iron-based materials.

Valve stem end

In order to reduce wear, the valve stem end is treated with induction or flame hardening. In special cases, weld surfacing with special materials on the shaft end is also possible (see “Armour materials”).

Wear in the shaft area is reduced through appropriate surface treatments.

Pulse plasma nitriding
As early as 1930, steel components were nitrided by means of a glow discharge in a vacuum. However, thanks to modern microprocessor technology, it is now possible to precisely control the nitriding process in the plasma.
The special layer structure with a very smooth single-phase surface area ensures optimal wear protection. In addition, the whole valve features a very good corrosion resistance, which proves beneficial when using aggressive fuels such as heavy oil, biogas or landfill gas.
This is why plasma nitriding, due to its outstanding properties for sliding couples, is the first choice for valves.
The process also offers significant ecological advantages.

Bath nitriding
Classic process to improve the sliding properties and to provide protection against wear.

Hard chrome
For a long time it has been the first choice for valve stems. Only seldom used due to the high environmental impact. This raw material will be banned soon.

Chromium nitride (CrN)
Common wear protection for titanium valves.

Full valves
Hollow valves, drilled
Hollow valves, drilled, sodium-filled
Hollow valves with enlarged cavity (turned/friction welded)
Hollow valves with enlarged cavity (turned/friction welded), sodium-filled


The valve guide guides (as the name suggests) the valve in the cylinder head. The valve guide has the additional function of discharging thermal energy from the valve into the cylinder head.

Gray cast iron GG25
Standard material for valve guides

Gray cast iron with increased phosphorus content GGP70
Cast material with increased phosphorus content for optimum wear resistance.

Special brass CW713R
CuZn37Mn3Al2PbSi / CuZn40Al2 / 2.0550
CW713R is characterized by high wear resistance and good corrosion resistance with good thermal conductivity.

Sintered material IEC120S
Powder metallurgically manufactured valve guides for high-performance applications. Pearlitic/ferritic matrix with embedded carbides.
Especially useful for critical applications, for example in biogas or landfill gas engines.


Valve guides are nitrocarburized, among other things, for optimum wear resistance

Valve guides are supplied with oil drilling, lubrication grooves or other accessories for different applications.

IEC manufactures all types of valve guides you need.


The valve seat and the valve together form the seal for the combustion chamber. They constitute a tribological system that has to withstand millions of load cycles and also to discharge large amounts of thermal energy into the cylinder head.

IEC develops and manufactures valve seat rings for all applications.

Cast or sintered materials such as:

Stellite 1
Stellite 3 / J3
Stellite 6 / J6 / P65
Stellite 12 / P58
Stellite 19 / PL6N / GGZV30-4
GGz 1.2599
Tribaloy T-400 / J10
PL12MV / GHS-2 / GZX190CrMo12-2
X210Cr12 / PL34
X45CrSi9-3 / PL33M10
CrNi 6040

e.g. Tinning of the outer contour for sealing

Water-cooled valve seat rings

Armoured / hard faced valve seat rings


The valve spring closes the valves after opening through a camshaft or a pneumatic or electrical actuator.

IEC develops and manufactures valve springs for all applications.

All common valve spring wires such as

Oteva 70
EN 10270-2-VD-SiC

Round or elliptical wires

Phosphating and oiling
Nickel plating

Symmetric or asymmetric
Cold or hot setting

Vibratory grinding
Hardening and tempering
Shot peening or sandblasting
Vibratory finishing


The valve cotter holds the valve in the spring retainer. There are clamped and non-clamped connections so as not to hinder the free rotation of the valve.

IEC supplies and manufactures valve cotters for all applications.


Cold forging


Chromium nitride


IEC designs and manufactures valve spring retainers from different materials for all conceivable areas of application and needs.


The valve rotator ensures the constant rotation of the valve during operation.
This reduces wear and decreases the amount of debris.

Rotators for valves are available in various designs. Among other things, valve rotators are known under their brand names Rotocap (TRW) or Turnomat (MWH).

IEC designs and manufactures or distributes valve rotators for your needs.

Rotators with ball-spring mechanism

Rotators with a spring (garter spring rotator)