When process equipment fails due to mechanical breakdown and/or corrosive attack, organizations risk human safety, environmental damage, product quality and the high costs of repair. Determining what went wrong, how, and why are crucial to eliminating any possibility of repeating a failure.
For over 25 years, ATI Wah Chang has provided its clients with the capability to accurately determine equipment failure causes and to make applicable recommendations for future failure prevention.
ATI Wah Chang combines its experience with the unique capabilities of its laboratories to identify corrosion attack methods and confirm the conclusions of our investigations.
Following a systematic engineering approach, we provide full service Failure Analysis, including:
- Thorough laboratory analysis
- Detailed explanation of the failure cause
- Practical advice and guidance for failure prevention
- And expert-witness testimony if necessary
We offer Failure Analysis resources you can depend on, and the knowledge and experience you can trust.
Failure Analysis Experience
While we have long been known as the authoritative resource for reactive and refractory metals, we also offer the knowledge, experience and facilities to investigate failures in a wide range of other materials.
We utilize state-of-the-art technology and equipment and take full advantage of on-site analytical, metallurgical, and corrosion laboratories, along with the in-depth knowledge of our highly qualified team.
Common Types of Equipment Failures Analyzed
Our experienced technical engineers, chemical engineers and laboratory staff have experience helping clients understand different modes of corrosion within processes and the effectiveness of different corrosion control measures.
Our Failure Analysis services have been used by a wide variety of industry professionals, from equipment fabricators and OEMs to process owners and end-users, in applications as varied as chemical processing and aerospace.
An incremental loss of material from a solid surface due to mechanical interface between that surface and a fluid, most commonly a multi-component fluid, or solid particles carried with the fluid or liquid and a gas. It is further defined as, a combined action involving both corrosion and erosion in the presence of a dynamic corrosive fluid, leading to accelerated attrition. Erosion can be broken down into several types, cavitation, liquid impingement erosion, solid impingement erosion, and beach erosion. [back]
Galvanic corrosion can be accelerated by an electrical connection with a more noble metal or nonmetallic conductor in a corrosive electrolyte. When electrical conductors are in contact they are galvanicly coupled, when this occurs an electrical potential is created and the less noble conductor under goes anodic attack. The anode sacrificially corrodes there by supplying a protective electron to the more noble electrode. [back]
A chemical or electrochemical deterioration of materials, caused by contact with the local environment. Deterioration can be evidenced by the loss of material or accumulation of corrosion product, usually material oxides. General corrosion occurs at local concentration cell anodes. The electrical potential on the metal surface is constantly changing causing the anodes to travel from one local peak to the next in a random pattern, causing uniform corrosion. [back]
Corrosion occurring preferentially at grain boundaries, usually with slight or negligible attack on the adjacent grains. This is also referred to as intercrystalline Corrosion. [back]
For common alloys, pitting attack is autocatalytic and pit initiation is an anodic reaction. Conditions that favor pitting: surface impurities; oxidizing impurities in solution, the most common cause of failure due to pitting is the presence of chloride-containing media; stagnant conditions.
Further, pitting is also known as Catastorphic Corrosion, due to its unpredictable nature. The depth and migration rate of pits are unknown and can cause unexpected failure. Pitting corrosion is un-uniform, 90% of the metal surface could be protected, but be attacked in localized passive regions and cause failure. [back]
Stress Corrosion Cracking
This type of cracking requires the simultaneous action of corrosion and sustained tensile stress, both internal (residual) and external (applied). Residual stress seems to be just as costly to the material in corrosive environments than does applied loading.
Because of the effect, stress corrosion cracking can be used to indicate the presence of residual stresses, as a qualitative stress test. Care needs to be taken to ensure the residual stress in the materials of choice have been relieved. Stress-Corrosion cracking may occur in combination with hydrogen embrittlement. [back]