Whether in mechanical engineering, hydraulic systems or pipework construction - components are often exposed to harsh conditions during use. Moisture, salt, temperature fluctuations or chemical influences attack metals and can lead to corrosion. The consequences are not only visually unattractive, but can also impair safety and functionality.

This is particularly true for outdoor and heavy-duty applications, for example:

• mobile construction machinery

• Agriculture and forestry

• Truck and commercial vehicle hydraulics

• Ship and harbour hydraulics

• Offshore platforms

• Oil and gas industry

• Wind turbines

• Hydraulic steel construction

• Coastal and flood protection systems

Wherever components are permanently exposed to moisture, salt spray or splash water, reliable corrosion protection is crucial.

For our customers, this means that corrosion-resistant products extend the service life of systems, reduce maintenance work and lower operating costs in the long term. In order to guarantee this quality in the long term, we not only have to develop surface coatings, but also test them reliably.

Corrosion is the chemical or electrochemical attack on metals by their environment. The most common form is rust formation in steel, caused by reaction with water and oxygen.

Consequences of corrosion:

• Weakening of the component strength

• Leaks in hydraulic systems

• Malfunctions

• Increased maintenance and replacement costs

Particularly vulnerable applications:

• Mobile construction machinery and forestry equipment

• Agricultural machinery and trailers

• Offshore and marine applications (salt water, spray)

• Harbour facilities and cranes

• Oil and gas industry (pipelines at risk of splashing water)

• Wind power and open-air systems

• Coastal infrastructure

Corrosion can occur due to various causes and circumstances. A distinction is therefore made between several types:

• Surface corrosion (uniform corrosion)
  Widespread, surface is removed evenly, e.g. uniform rust coating

• Pitting corrosion (pitting)
  Very localised and deep, leads to punctual breakthroughs, critical for pressure pipes

• Crevice corrosion
  Occurs in narrow gaps or overlaps, difficult to access and visible

• Contact corrosion (galvanic corrosion)
  Between different metals in a conductive electrolyte, e.g. steel and aluminium without insulation

• Stress corrosion cracking
  Combination of mechanical stress and corrosive environment, leads to sudden failure

• Intergranular corrosion
  Along grain boundaries in the microstructure, critical for certain stainless steels

Protective measures

• Galvanic coatings (e.g. zinc/nickel)

• Paintwork and powder coatings

• Anti-corrosion oils and waxes

• Use of corrosion-resistant materials such as stainless steel

• Constructive corrosion protection (avoidance of gaps)

The salt spray test is one of the most frequently used methods worldwide for testing the corrosion resistance of materials and coatings under standardised conditions. It is internationally standardised, including in ISO 9227 and ASTM B117.

Briefly explained

In a special test chamber, a 5 % sodium chloride solution (salt water) is finely atomised and continuously sprayed onto the test parts as a mist. The ambient temperature is kept constant at 35 °C. This simulates an aggressive, corrosive atmosphere and thus enables a comparable assessment of the protective effect of coatings.

Procedure of the test with us

• Preparation: Components are carefully cleaned and placed in the chamber.

• Spraying: The salt fog solution is distributed as a fine mist over the test surfaces.

• Test duration: Depending on the application and the protection class, e.g. over 3000 hours.

• Cleaning: After the test, the samples are rinsed with deionised water.

• Evaluation: Visual inspection for signs of corrosion such as rust, blistering or infiltration of the coating.

• Documentation: All results are recorded and analysed in detail.

The advantage of the procedure lies in its standardisation and comparability. This means that different coatings or supplier components can be objectively compared.

We have specifically expanded our testing capabilities with a modern salt spray test rig from Erichsen. This doubles our testing capacity.

What does this mean in concrete terms?

• More samples can be tested at the same time

• Possibility of serial testing with systematic variants

• Comparison of our own products with components from suppliers or competitors

• Faster availability of reliable results for development and quality assurance

This investment is part of our commitment to the highest product quality and customer satisfaction. Because only with sound tests can we ensure that our surface coatings provide long-term protection in practice.

A particular focus is on optimising our zinc/nickel coatings. These are used in many of our products to ensure outstanding corrosion protection under high mechanical stress.

With the new test bench we can:

• Systematically compare different coating formulations

• Making data-based decisions for series release

• Checking the quality of purchased parts and comparing them with our standards

• Support our customers with clear, reliable statements about the durability of our products

The goal: Consistently high quality in the long term - regardless of batch size, production location or supplier.

We therefore test specifically for real loads that occur in applications in which our products are installed:

• Hydraulic systems in outdoor use (construction and agricultural machinery)

• Coastal areas and harbour facilities with high salt pollution

• Offshore platforms and shipbuilding with salty spray

• Industrial plants with chemically polluted air

• Outdoor wind power and energy systems

These practical tests ensure that our coatings can withstand the challenges of a wide range of industries.

In addition to the classic salt spray test (SSNT) in accordance with ISO 9227 / ASTM B117, there are other standardised test methods that are tailored to different requirements. Cyclic tests in particular are considered to be more practical because they reflect realistic weather changes.

Comparison of common corrosion tests

Explanations

• ISO 16701 (Accelerated cyclic corrosion test): Simulates alternating loads caused by salt spray, high humidity and drying. The corrosion mechanisms are more similar to real outdoor conditions and are recommended for components permanently used outdoors.

• SAE J2334 (Cosmetic Corrosion Lab Test): Specially developed for the automotive industry, this method tests cosmetic corrosion (rust infiltration on painted components) under winter conditions (road salt, moisture, temperature fluctuations).

Why STAUFF relies on the salt spray test

The salt spray test in accordance with ISO 9227 / ASTM B117 is the appropriate standard procedure for our hydraulic components and connecting elements.

Reasons

• Globally standardised and recognised with reproducible conditions

• Good comparability of results - internally and with competitor and supplier components

• Perfectly suited for our zinc/nickel coatings, which are developed for extreme outdoor and industrial applications

• Expanded testing capacities allow more flexible and systematic use of this test

In this way, we ensure that our coatings provide reliable protection under the toughest conditions - whether in agricultural machinery, offshore facilities or wind turbines.

The salt spray test in accordance with ISO 9227 / ASTM B117 is the appropriate standard procedure for our hydraulic components and connecting elements.

Reasons:

• Globally standardised and recognised with reproducible conditions

• Good comparability of results - internally and with competitor and supplier components

• Perfectly suited for our zinc/nickel coatings, which are developed for extreme outdoor and industrial applications

• Expanded testing capacities allow more flexible and systematic use of this test

In this way, we ensure that our coatings provide reliable protection under the toughest conditions - whether in agricultural machinery, offshore facilities or wind turbines.

The demands on surface coatings are increasing worldwide - due to tougher operating conditions and stricter standards. By expanding our testing capacities, we are ensuring that we can continue to respond to these requirements in a competent and fact-based manner in the future.

For our customers, this means

• More safety in the application

• Traceably tested quality

• Longer product service life

• Lower maintenance and replacement costs

Investments in our testing technology are investments in the future - and a clear commitment to quality and reliability.

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