Exam 1: Corrosion and Materials

Changing to a more corrosion resistant and/or higher hardness material _________ improve cavitation resistance.

With thermal fatigue, time to failure is a function of the magnitude of the stress and the number of cycles and decreases with _________ stress and ________ cycles.

Typical HF Alkylation units operate with 1% to 3% water in the acid, equivalent to an HF-in-water concentration of 97% to 99% and the temperatures are generally below _________.

Reheat cracking is most frequently observed in _______ grained sections of a heat-affected zone.

With 885º F embrittlement, increasing amounts of ________ increase susceptibility to damage when operating in the high temperature range of concern.

Which of the following is not a method used to prevent brittle fracture?

Hydrogen blisters may form at many different depths from the surface of the steel, in the middle of the plate or near a weld. In some cases, neighboring or adjacent blisters that are at slightly different depths (planes) may develop cracks that link them together. Interconnecting cracks between the blisters often have a __________ appearance.

A hard, brittle surface layer will develop on some alloys due to exposure to high temperature process streams containing high levels of nitrogen compounds such as ammonia or cyanides, particularly under reducing conditions, is called _______.

Ammonium chloride salts are hydroscopic and readily absorb water. A ________ amount of water can lead to very aggressive ammonium chloride corrosion.

Mitigation of CUI is best achieved by _________.

Ammonium chloride salts may be whitish, greenish or _________.

Carburization can be confirmed by substantial increases in _______ and loss of __________.

With high temperature hydrogen attack, ________ using a combination of velocity ratio and backscatter have been the most successful in finding cracking.

Steel hardness, __________ and stress are critical factors in causing hydrogen stress cracking.

__________ is usually found in aqueous environments or services where water is sometimes or always present, especially where stagnant or low-flow conditions allow the growth of microorganisms.

__________ is a form of stress corrosion cracking normally occurring during shutdowns, startups or during operation when air and moisture are present. Cracking is due to sulfur acids forming from sulfide scale, air and moisture acting on sensitized stainless steel.

A vacuum tower operating at 740º F is being entered to inspect. Several sets of Type 410 SS trays are bent at various angles. The trays are removed in order to straighten them. When an attempt is made to straighten them cracks form at the bends. What type of damage mechanism would cause the cracks to form?

If weld repairs are required, the effects of temper embrittlement can be temporarily reversed (de-embrittled) by heating at ______ for 2 hours per inch of thickness and rapidly cooling to room temperature.

__________ caustic concentrations and ________ temperatures increase the likelihood and severity of cracking with caustic embrittlement.

What method is most used to assure boiler feed water corrosion is not occurring?