Self-displacement effect

As shown previously, anticorrosion properties are the result of a complex steady-state situation in which several phenomena are in action (i) displacement of the electrochemical interface, (ii) ennobling and self-healing effects, (iii) barrier effect offering nonspecific protection. 

As contrasted with stress from sustained loads such as internal pressure or weight, displacement stresses may be permitted to cause hm-ited overstrain in various portions of a piping system. When the system is operated initially at its greatest displacement condition, any yielding reduces stress. When the system is returned to its origin condition, there occurs a redistribution of stresses which is referred to as self-springing. It is similar to cold springing in its effects. 

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