Failure mechanisms

What is a failure mechanism

A failure mechanism as described in this database is a detailed description of a technical failure mode. Most failure mechanisms are physical degradation of components due to operational conditions combined with component features like design, materials and surface treatments. Other failure mechanisms can result in technical faults without being destructive, like unacceptable increase of friction for a sliding sleeve valve. Both types of failure mechanisms are influenced by several factors that must be known to predict the presence and severity of the mechanism. 

Failure mechanisms described in this database are short and structured summaries to help practical people understanding the basics of the mechanisms. Always involve failure mechanism experts before making decisions related to the presence and severity of failure mechanisms.

Metal structure components

Failure mechanisms categories related to metal structure components are:

• Corrosion
• Cracking
• Deformation
• Embrittlement
• Fatigue
• Fracture
• Friction
• Wear

Polymer seal components

Failure mechanisms related to polymer seal components are:

• Abrasive wear
• Bad resilience
• Compression set
• Dieseling
• Explosive decompression
• Extrusion
• Friction
• Hardening
• Installation damage
• Nibbing
• Shrinking
• Spiralling
• Swelling

Electric components

Specific failure mechanisms related to electrical components are:

• Dielectric breakdown
• Electromigration
• Induced current
• Voltage drop

Electrical components may also have failure mechanisms related to metal structures and polymer seals.

Further discussion

Operational conditions consist of environmental conditions and physical loads. These conditions must be known to predict a failure mechanism. Use the link to the database for operational conditions below for more information about the subject. Component features will also have influence on the failure mechanism resistance. That could be geometry details (notches, material defects, surface roughness, tolerances, etc), type of materials and surface treatment. Use the link to the databases for design, materials and surface treatments below for more information about these subjects. Failure mechanisms can occur both in the component itself (like wear of car tyres) and at the component interface (like wear of the road). A failure mechanism in the interface may change the operational condition (more water on the road) resulting in a component failure (aquaplaning). The risk model below shows the relations between failure mechanisms and influencing factors.

• Operational conditions
• Design
• Materials
• Surface treatments
• Risk model 

This failure mechanism database is an adequate tool for finding potential failure mechanisms in non-standard components, standard components in a non-standard environment or standard components where a track record is unknown.

This database is thus a perfect tool for designers when performing the ‘core team analysis’ in the failure mode, effect and criticality analysis (FMECA) of new technology. The analysis will be reviewed by material experts during the ‘review team analysis’. The database will also be a perfect tool for operators working with well integrity issues. These people should have an idea of potential failure mechanisms related to e.g. H ₂ S values above values described in the design basis. The material experts has the responsibility for make decisions related to this issue, but by using this database, the operators improves their understanding of the mechanisms that may take place if actions are not taken. 

Finally, have in mind that damages of components often are the result of a combination of several failure mechanisms.

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