What are the capabilities required by high-quality fuel injection lines?

Resistance to pressure

We develop a custom-tailored solution for every new project. We produce tubes in GUIDO steel grades ST30, ST50, ST70 and ST90. These are micro-alloyed fine grain structural steels developed and specified specially by us for use in fuel injection lines. The outer and inner diameters are selected individually for each project.

We achieve the specified pressure resistance by means of autofrettaging, the selective introduction of residual stresses in the tube wall to increase the dynamic resistance to pressure, in combination with the finishing of the inner wall of the tube to a very high quality. Pressure resistance is tested both at the development stage and during serial production on a number of dynamic pulse testing rigs. On top of that we also carry out metallurgical tests and tests on the materials.

Resistance to vibrations

GUIDO steel grades ST30, ST50, ST70 and ST90 also contribute to resistance to vibrations. For every connection variant our design engineers develop an individual swaging geometry which is optimised in vibration terms. Potential weaknesses are identified and eliminated at the outset during the development stage of a new fuel injection line with the assistance of computer simulations and modal analyses. Similarly to pressure resistance, resistance to vibrations is also tested on dynamic testing rigs over the course of the entire development period and with repeated tests during serial production as well.

For every new engine project our applications engineers carry out comprehensive vibration analyses with concluding findings directly on site at the customer’s premises. The sensors required to do this can generally be fitted to the engines quickly without any interference with the engine.

Cleanliness

Needless to say we comply with the cleanliness stipulations relating to all high pressure fuel injection systems for diesel engines commonly used around the world. GUIDO fuel injection lines with clean inner tube surfaces are the basis for clean components later on. Clean rooms in production, permanent monitoring of standards using state-of-the-art measuring instruments, and special packaging ensure that our customers can count on taking delivery of a component which, as a minimum, meets requirements in terms of cleanliness.

Seal tightness

Meticulous design and tolerance analyses of the connection geometries enable us to guarantee that our fuel injection systems offer optimised and long-lasting seal tightness.

Numerous validation checks as part of the release testing process provide documentation of the assembly process and seal tightness for every project, and this includes the ageing process too.

The burst pressure and seal tightness of the connections are machine-tested on a 100% basis at the large-volume production stage – just one element of our zero-defect policy.

Resistance to corrosion

In terms of the selection of suitable means of protection against corrosion for our metal products we ensure that the protection does not impair their functionality in any way. Ungalvanized sealing faces, for instance, have been standard for GUIDO fuel injection lines for more than four decades.

As a general principle we never use any systems of protection against corrosion which are included in black lists or grey lists because of chromium 6 or other substances.

In-house surface treatment facilities and their waste water treatment facilities naturally comply with all environmental standards and are subject to strict internal and external monitoring.