Art of Welding : Guichon know-how

Welding is one of the most critical operations in valve manufacturing.

With a dedicated department and a team of qualified welders, Guichon Valves has made welded construction its speciality.

Example of welder qualification

All welds are done by hand according to TIG or MIG techniques:

TIG welding  is an arc welding procedure with a non-consumable electrode.  TIG is an acronym for “Tungsten Inert Gas” where “Tungsten” indicates electrode material and “Inert Gas” indicates the type of plasma gas used.  The arc is created between the consumable electrode (- generator) and the part (+ generator) under a gas flow.  Generally speaking, it consists of a gas or a mixture of rare gases. (In particular, argon and helium, or a mix of the two).

MIG welding (Metal Inert Gas) –the fusion of metals is obtained by a heat energy generated by an electric arc which bursts in a protected atmosphere between the electrode wire and the parts to be assembled.

The distinguishing characteristic of Guichon is its capacity to weld all types of metals (Stainless steels: 316L, 321, Carbon steel A105, P265GH…) but most importantly exotic metals such as Uranus B6, Duplex, Nickel and Nickel alloys Alloy 20, Hastelloy™, Inconel™, Incoloy™, Monel™ or other special metals such as Titanium, Zirconium, Tantalum,…

Indeed the complexity of this type of welding is due to special precautions which must be implemented as the materials are highly reactive to contamination by ambient air.


Guichon Valves is equipped with a vacuum tank for welding, meeting the requirements mentioned above, and assuring good quality welds for these special alloys.

Another operation performed in the welding department is the deposition of Stellite grade 6 and grade 21, which involves covering metal with a superficial layer of melted Stellite.  This process is used to reinforce zones of the valve having metal to metal contact that could wear out prematurely if not hard faced with Stellite.

Before Stelliting              After Stelliting                       After machining

Finally, non-destructive testing such as dye penetrant testing (our authorization COFREND Level 2) and X-rays (from accredited companies) are performed to validate the compliance of the welds.

Penetrant Test Step 1 : apply dye

Penetrant Test Step 2 : put in place the indicator