DNV GL certificate for the Stauff Connect forming system

Source: press release, 18 July 2019

The compact forming machine is particularly quiet and easy to operate
The compact forming machine is particularly quiet and easy to operate (photo: Stauff)

The DNV GL Group marine classification company has tested the Stauff Form system and approved it for maximum operating pressures of up to 800 bar. The approval applies to operation with hydraulic oil and lubricating oil but also with heavy oil, compressed air, oxygen, steam, freshwater and seawater.

The DNV GL testers performed leak, burst pressure and bend pressure cycle pulse tests and tested the components under vacuum, subjected to severe vibrations and also their fire resistance. The certificate documents that these tests were passed successfully.

Stauff Form is a forming system within the Stauff Connect range, which is characterised by its exceptionally simple assembly and extremely high safety levels. The Stauff form ring is pressed onto the tube end with a fixed and therefore captive elastomer seal. This creates a positive connection which provides a reliable, permanent and maintenance-free seal on the only possible leakage path when used in combination with a conventional fitting body with a 24° inner cone and a union nut compliant with ISO 8434-1. The sealing effect is supported by the system pressure of the hydraulic system so that Stauff Form is ideal for high-pressure applications. The developers focussed specifically on the final, manual installation steps of the forming system in the fitting body. The installer tightens the union nut to the point where the force increases noticeably and completes the installation with another turn of 15° to 20° beyond this point. A clearly discernible torque increase indicates that the installation has been completed, which means that insufficient or excessive tightening is virtually impossible.

The forming process is also user-friendly with a compact, quiet forming machine operated by a touch pad with plain text display. Tube shapers, for example, can easily be changed via a bayonet lock. Stauff Form is available for steel and stainless-steel tubes with dimensions of 6 x 1.5 mm to 42 x 4 mm (Light Series) and 6 x 1.5 mm to 38 x 6 mm (Heavy Series).

The Stauff Connect range is ideal for use in maritime applications as it offers corrosion protection that goes beyond previous market standards thanks to its high-quality zinc/nickel coating. For instance, over 1,200 hours resistance to red rust and base metal corrosion were achieved in the salt spray test in line with EN ISO 9227, which clearly exceeds the highest corrosion protection class K5 as defined by the VDMA in standards sheet 24576.

From the point of view of users in the shipping and offshore industry, this type of corrosion protection also offers the advantage of remaining effective even after possible mechanical damage to the fitting, which can never be rules out in challenging shipping and port environments. If the surface is damaged, only the top layers of sealing and passivation might be removed, but not the zinc/nickel layer underneath which provides the actual corrosion protection. The coating is also highly ductile which makes it less susceptible to damage.