Multiple Choice Questions on

Forms of Corrosion

Questions 11 - 15

Page 3 of 4


11.

Steel plates with aluminum rivets were exposed to seawater for ten weeks.  What would corrode?

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The aluminum rivets

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The steel plate

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Both


12.

Two dissimilar metals of equal area that are in contact are to be coated but enough coating is in hand for only half of the total area.  With this limitation, which one of the following must be coated?

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Half of the anode and half of the cathode

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Only the cathode

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Only the anode

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Both


13.

An uncoated pipeline lies in a trench in an undisturbed soil and it is covered by a backfill.  Would this pipe be subjected to localized corrosion?

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No, the backfill being impervious would not alloy air to pass

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Dry moisture/wet moisture cells would be immediately formed

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No, differentiation aeration cells would be formed

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Yes, because differentiation aeration cells would be formed


14.

Consider the stabilized grade of steel (steel 347 containing 2% Mo).  This steel is heated to 2300EF and quenched in water.  The steel was later stress-relieved for half-an-hour at 1200EF.  Would this steel be subjected to intergranular corrosion?

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Yes

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No


15.

Which of the following methods is most appropriate to prevent stress corrosion cracking?

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Adding inhibitor to the system

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Lowering the carbon content to 0.03%

  [  ]

Stress-relieving of steels

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Using high temperature solution treatment commonly termed annealing