Hardening of ball valve components using ion-chemical heat treatment - Mashproject LLC

Hardening of ball valve components using ion-chemical heat treatment

Hardening of ball valve components using ion-chemical heat treatment

Shut-off valves are present in all pipeline systems of industrial facilities, technical objects for domestic use (heating, gas, water supply, sewage, etc.), and make up at least 80% of the total number of products used in the pipeline.

Shut-off valves regulate the flow of the working medium to ensure the specified parameters of the technological process - this includes closing, opening, changing the direction, and speed of the movement of gas or liquid.

The most commonly used shut-off elements are valves. In particular, ball valves are widely used, whose advantage lies in the simplicity of the design and minimal time to block the flow of the working medium. The component responsible for closing or regulating the cross-section of the flow channel is made in the form of a ball or a ball plug with a hole. These products are made from structural or stainless steels, titanium, bronze, and other materials.

A feature of ball valves is their relatively small size compared to similarly purposed pipeline fittings. This type of valve is installed in places where the use of gate valves is impossible due to limited space.

ball valve - hardness measurements

Such products are often operated under harsh conditions. The valves handle aggressive media – acids, cracking products, etc.; petroleum products with CO2 and H2S; internal parts may be subjected to deformation due to strong flow pressure. Therefore, to extend the service life of these valves, they must undergo surface hardening.

Ion chemical-thermal treatment (ICT) is one of the advanced and innovative methods of hardening products. Vacuum hardening methods achieve the best characteristics of the hardened surface, improving wear and galling resistance, resistance to erosive and cavitation wear, as well as intergranular corrosion for all steels and alloys. The warranty life and operational reliability of hardened products are increased many times, as confirmed by production tests.

This article presents the results of production tests by the company "Ion Technologies" on the hardening of the working surfaces of the shut-off mechanisms of ball valves. The developed ICT technology allows ball valve manufacturers to quickly set up production of wear-resistant products that meet modern requirements.

The main materials for making ball valves are stainless steels (12X18H10T, 14X17H2, 08X17H13M2T, 10X17H13M2T), titanium alloys, and others.

Ion Chemical-Thermal Treatment of Stainless Steel Parts

Parts before hardeningICT hardening processParts after hardening
ball valve plugs
ball valve plugs
Ion chemical-thermal treatment of valves
Ion chemical-thermal treatment of valves
Ion chemical-thermal treatment of ball valve plugs
Distribution of microhardness
by the depth of the nitrided layer
Distribution of microhardness by the depth of the nitrided layer

After ICT, surface hardness measurements of ball plugs and other hardened parts were made using a portable ultrasonic hardness tester TKM-459C.

hardness tester TKM-459C Mashproject - ball valve plugs

Characteristics of the Nitrided Layer in Steels 12X18H10T, 14X17H2

Steel Grades Parameters12X18H10T14X17H2
Surface Hardness HV 10, kgf935 - 1015975 - 1015
Surface Hardness HV 5, kgf775 - 825810 - 825
Case Depth, mm0.4 - 0.450.38 - 0.43

Characteristics of the Nitrided Layer of VT-3 Titanium Alloy Parts

Parameters of Titanium AlloyVT-3
Surface Microhardness HV 0.1, kgf875 - 955
Layer Depth by Microstructure hm, µm10 - 15
Layer Depth by Microhardness hc, µm70
Brittleness on the VIAM ScaleGrade I, not brittle
Nitrided Layer MicrostructureNitrided surface layer of VT-3 titanium alloy
Microhardness Distribution
by the Depth of the Nitrided Layer
Microhardness distribution by the depth of the nitrided layer on VT-3 titanium alloy

The ICT technology improves the operational characteristics of products. It ensures dimensional and finishing accuracy for future design requirements, while eliminating additional mechanical and grinding operations and/or honing, which significantly reduces costs and increases production rates.

Material published with the consent of LLC "Ion Technologies"