New junction technique VTTJ (Vacuum Tight Threaded Junction)

The VTTJ technique permits to make low cost metallic junctions compatible with aggressive environments (high temperature, flames, high thermal fluxes, high vacuum etc.):
a good alternative to welding!
* Applicable also to join non weldable materials and for heterogeneous joints (e.g. between steel and copper)
* Tested up to 500 bar internal pressure and up to 200° C, with excellent leak tightness
* Adopted for many scientific applications in Nuclear Fusion research; now being licensed to industry

Possible applications: junctions on heat exchangers, hydraulic plants, boilers etc. in manufacturing, chemical, food, pharmaceutics, oil industry etc.

Main advantages with respect to welding or brazing:
* Easy construction
* Low cost (can be made using a standard manufacturing equipment)
* High reliability (passed several tests in critical conditions)

VTTJ is an international patent of Consorzio RFX, available at:

Short description pdf available here
Breve descrizione in pdf scaricabile qui

Articolo apparso sulla rivista AICARR Journal scaricabile qui
Paper appeared in the AICARR Journal available here
Articolo apparso sulla newsletter dell'AIV (Associazione italiana di Scienza e Tecnologia) scaricabile qui

For more information: piero.agostinetti @
Tel. +39 049 8295087


The VTTJ concept: (a) sample for the application on the SPIDER extraction grid; (b) section of the sample for the application on the SPIDER grounded grid; (c) prototype of an extraction grid for the SPIDER experiment; (d) detail view of the VTTJ junctions.