System Features

Design, functionality and properties of the STAUFF Form EVO tube forming system

System structure and components

The system, which is based on standard components, consists of only four essential components:

The STAUFF Form EVO sealing ring is pushed onto the tube end with the contour previously formed by machine. In combination with a conventional fitting body with 24° inner cone and a union nut according to ISO 8434-1, a form-fitting connection is created that seals securely, permanently and maintenance-free.

Variability and flexibility

Users benefit from a high degree of variability and flexibility as well as numerous combination and adaptation options, which result from the use of all standard components of the STAUFF Connect product range.

There is no need to stock similar components twice, with a correspondingly high risk of confusion, as is often the case with comparable systems. Material and logistics costs can be reduced accordingly.

Materials and surfaces

All components of the STAUFF Connect product range are finished with the high-quality STAUFF zinc/nickel surface as standard.

With more than 1,200 hours of resistance to red rust / base metal corrosion in the salt spray chamber according to DIN EN ISO 9227, this offers reliable corrosion protection far beyond the standards that have been common on the market to date.

Even after transport, processing and assembly of the components, the requirements defined in VDMA standard sheet 24576 for pipe connections for the highest corrosion protection class K5 are clearly exceeded.


The only possible leakage path is sealed primarily by the STAUFF Form EVO sealing ring, which is specifically positioned between the surface of the tube and the 24° inner cone of the fitting body during assembly.

FKM (Viton®) is used as the sealing material in the standard delivery. This enables the problem-free use of the STAUFF Form EVO tube forming system for applications with high temperatures or aggressive media. Thanks to the combined metal-elastomer seal, use in low-temperature ranges down to -35° C is also possible without restrictions - as is also the case with NBR (Buna-N®).

The unique sealing profile has a particularly large cross-section in order to provide a secure and permanent seal even if the tolerances of the tube and fitting are unfavourable. Possible errors during assembly on the formed tube end are consistently avoided by the laterally identical profile of the sealing ring. The sealing effect is supported by the system pressure of the hydraulic system, so that the STAUFF Form EVO tube forming system is excellently suited for high-pressure applications.

Final assembly in the fitting body

Final assembly is carried out by tightening the union nut to the point of a clearly noticeable increase in force. The assembly is completed with a further turn of about 15° to 20° beyond this point.

For the user, this conceivably simple variant of assembly results in numerous advantages:

  • Significantly lower tightening torques and short assembly distances (after reaching the fixed point).
  • Clearly noticeable torque increase, which signals the end of assembly
  • Maximum safety against over-assembly
  • No time-consuming and cost-intensive qualifications of the workers required to perform the work

Pipe connections made with STAUFF Form EVO can be loosened and reassembled as often as required without wear, as damaging expansion of the 24° inner cone of the fitting body can be technically ruled out.

Pressure resistance

As a result of extreme care in the development of the system and the selection and processing of materials, the STAUFF Form EVO tube forming system in combination with original parts of the STAUFF Connect product range offers a pressure resistance of up to 800 bar in the Heavy Series and 500 bar in the Light Series (with a fourfold safety factor and depending on the series, design and size of the fitting body as well as taking into account various factors for pressure reduction).

Due to the contour formed on the tube end, maximum pull-out resistance can be achieved with the system.

Further Information