Salt Spray Testing

Salt spray testing uses a closed chamber to subject samples to a saline (or salt) spray. This test is generally performed to evaluate the integrity of a coating in a corrosive environment, or to test the corrosion resistance of a product or material.

Salt spray testing may also be referred to as neutral salt spray (NSS), because the pH level of the saline is between basic and acidic. Depending on the standard or test plan chosen, samples are exposed to the spray solution for a predetermined period of time, and checked regularly throughout testing to evaluate their performance.

Typical results from this method include rusting, blistering, peeling, etc. The most commonly used standard for salt spray and neutral salt spray is ASTM B117.

Cyclic Corrosion Testing

When closely mimicking your extreme environment is key, Element’s variety of cyclic corrosion testing methods are a preferred choice.

Also referred to as modified salt spray, cyclic corrosion testing closely resembles traditional salt spray testing, which notable exceptions being the type of corrosive substance and the exposure durations and concentrations.

Typical cyclic corrosion testing variations include sulfur dioxide salt spray, electrolyte salt spray, and seawater acetic acid testing (SWAAT), which are covered under the ASTM G85 standard. This class of tests also includes Copper-Accelerated Acetic Acid Salt Spray (CASS), generally performed per ASTM B368, which is used to test nickel-based coatings.

Intergranular Corrosion Testing

Intergranular corrosion (IGC) refers to the deterioration of materials along grain boundaries. This is caused by a process known as sensitization, which occurs when a material is exposed to higher than normal temperatures, or exposed to extreme or prolonged heat.

Unlike other types of corrosion, IGC is not always visible; therefore, testing becomes an important checkpoint for materials that may have been compromised.

Popular test methods include the Huey Test, Streicher Test, Oxalic Acid Etch, and Strauss Test, which are performed under ASTM A262 (another similar standard is ASTM G28, which is specific to chromium alloys containing nickel). Testing helps ensure that materials, and their applications, are safe from corrosion and decay.

Pitting & Crevice Corrosion Testing

If a material exhibits holes or gaps on its surface, pitting or crevice corrosion may be the culprit. Pitting corrosion is characterized by small holes on a material. Crevice corrosion, on the other hand, occurs around the gap where two materials meet.

Both types of corrosion can be difficult to detect and predict, so understanding the risk factors of corrosion and susceptibility of a material can help anticipate issues before they arise.

Test methods such as ASTM G48 induce pitting and crevice corrosion in materials to measure how difficult it is to cause pitting corrosion or crevice corrosion, and how a material performs in a controlled environment relative to other potential materials.

Sour Service Corrosion Testing

Because of the extreme environments in which natural resources are harvested, the Oil & Gas sector faces some unique challenges. Sour service test environments are an invaluable tool for truly evaluating how equipment and materials will hold up in environments rich in hydrogen sulfide and other caustic gases.

In addition to hydrogen induced cracking (HIC), sulfide stress cracking (SSC) and slow strain rate (SSR) testing, it’s also important to assess how the mechanical properties of materials and components change in highly corrosive environments.