A substitute for Stellite™ on sealing surfaces


Today, the hardening of sealing surfaces is performed by welding a material harder than the valve body material.
Most of the time, this material is Stellite™, a cobalt-base. It is selected according to the grade: more or less cobalt, more or less hardness.

hardening of sealing surface industrial valves

« Stellite™ : Alloy of cobalt (from 50 to 65 %), chromium (from 25 to 35 %), tungsten (from 4 to 13 %), carbon (from 1 to 2,5 %) and other elements (molybdenum, nickel, iron, titanium). [Stellites are very resistant to wear, corrosion in acidic environment and hot oxidation. They are destined for parts’ lap or overlay weld (stelliting).] »

Source: www.larousse.fr


Despite its frequent use, cobalt is strongly discouraged in radioactive environments (particles released in the fluid become radioisotope). It also very badly bears some processes’ chemical attacks.
metal to metal seal industrial special valves guichonOn a valve, the sealing surface is subject to many constraints:

  • Mechanical pressure for tightness
  • Fluid attacking mechanical materials (abrasion) and chemical materials.

The Stellite™ has hardness, resistance and abrasion benefits. However, in cases it cannot be used, the problem is to be able to replace it with an equivalent performances’ material.

The solution proposed by Guichon Valves :

Therefore, Guichon proposes the use of a nickel base refilling mixture instead of a cobalt base.


  • A substitute to Stellite™ keeping a good hardness
  • Equivalent life-time
  • Less constraints (a lower melting point for deposit and a lack of cobalt)
  • Better resistance to corrosion in most cases
comparative table nickel based and cobalt based guichon valves Comparative table between Cobalt-base and Nickel-based


Relevant products and applications:

  • Generally speaking, the obturator/seat sealing surfaces
  • Nuclear and chemical applications