Introduction - hdbk1132990223

DOE-HDBK-1132-99

Premature component failure and poor performance are often the result of materials being

selected without an adequate evaluation of all the failure modes applicable to a component

and the materials of construction. In general, mechanical design codes have been excellent

in preventing failure due to mechanical design. Component failures due to rupture, overload,

or cyclic loading have steadily decreased and in some applications have been totally

designed out of the component. The majority of the failures and poor component

performance that occur are due to age-related degradation. The effects of thermal aging,

radiation, corrosion, erosion, cyclic fatigue, and instability of the material should be taken into

account. Cable products should be manufactured in accordance with Insulated Cable

Engineering Association requirements.

The responsibility of accounting for age-related degradation is with the design engineer,

who often does not have sufficient information to determine the level and types of age-

related degradation that apply.

Typical age-related degradation phenomena include for metallic materials the following:

general corrosion,

pitting attack,

intergranular corrosion,

stress corrosion,

galvanic corrosion,

crevice corrosion,

erosion corrosion,

microbiological-influenced corrosion, and

internal oxidation.

Of these age-related degradation mechanisms, only the general corrosion mechanism

can be addressed by the " ake thicker"approach. Each of the remaining mechanisms

is materials-dependent and may be affected by the following:

specific metal chemistry,

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