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NEW QUESTION # 22
Cold wall refractory lined components shall be dried out by heating from:
- A. the cold face only.
- B. the hot face only.
- C. inside an oven.
- D. the outside the steel shell.
Answer: B
Explanation:
Cold wall refractory systems are typically backed by steel shells, which are poor at withstanding the thermal stresses that come from reverse heating. API 936 and API TR 980 clearly emphasize thatthe heat-up or dryout process for cold-wall linings must always begin from the hot face- that is, the process-exposed surface.
Heating from thehot faceallows for controlled migration of moisture toward the cold face and eventual venting to the atmosphere. Conversely, heating from the cold face or steel shell side traps moisture between the hot impermeable material and the outer surface, leading to:
Steam buildup
Explosive spalling
Cracks in the material or at the interface with the steel
For these reasons,only the hot facemethod is specified unless the design and dryout plan justify a different method under special engineering review.
Reference:
API Std 936, Section 6.5.2: "Dryout shall be performed from the hot face only unless otherwise specified." API TR 980, Section on "Dryout of Cold Wall Systems": Highlights the mechanisms of vapor movement and the risks of reverse heating.
ASTM C1190(Referenced Method): Supports the use of correct drying schedules and methods.
NEW QUESTION # 23
The lining surface should remain uncovered and free from contact with moisture during the curing period for what type of refractory?
- A. Chemically bonded
- B. Ceramic bonded
- C. Hydraulic bonded
- D. Cement bonded
Answer: A
Explanation:
Chemically bonded refractories, such as phosphate-bonded or acid-bonded types, develop strength through chemical reactions that requireexposure to ambient air. These materials must remainuncovered and dry during curing, as moisture or covering may inhibit the required chemical bonding or lead to improper set.
Covering chemically bonded linings (e.g., with plastic sheeting or wet burlap) - practices appropriate forhydraulic bonded(cement-based) refractories - would trap moisture and interfere with the chemical reaction process in chemical bonds.
Reference:
API TR 980 -Monolithic Refractories: Installation and Dryout, Section on Chemically Bonded Refractories:
"Do not cover chemically bonded castables during the curing period. Keep surfaces exposed to air."
NEW QUESTION # 24
In accordance with TR 980, when curing a high-purity, low-cement castable for a high-temperature unit, which of the following sequences ensures minimum cracking risk?
- A. Dryout using open flame burners after form removal
- B. Steam curing for 48 hours followed by firing at 1500°F
- C. Accelerated drying using forced air at 400°F for 12 hours
- D. Air curing for 24 hours, followed by controlled heating ramp of 50°F/h up to 600°F
Answer: D
Explanation:
TR 980 outlines curing and dryout best practices for monolithic refractories. For high-purity low-cement castables, gradual heat-up is necessary to avoid thermal shock and cracking:
"A minimum 24-hour air cure at ambient temperature should be followed by a controlled dryout ramp not exceeding 50°F (28°C) per hour up to 600°F (316°C)."
- TR 980, Section 6.4.2
NEW QUESTION # 25
For qualification testing, test panels for pneumatic gunning are inclined at a:
- A. 60° angle above the horizontal.
- B. 30° angle above the horizontal.
- C. 90° angle above the horizontal.
- D. 45° angle above the horizontal.
Answer: D
Explanation:
When qualifying materials and personnel for gunning applications, the standard test panel orientation is:
"The gunned panels shall be prepared on steel plate forms inclined at 45° to the horizontal."
- API Std 936, Section 6.5.1, Gunning Test Panels
This standardized angle helps evaluate rebound and build-up in conditions that simulate typical applications.
NEW QUESTION # 26
Before application of a curing compound the hydraulic bond castable surface shall not be allowed to air dry longer than:
- A. 8 hours.
- B. 24 hours.
- C. 2 hours.
- D. 1 hour.
Answer: D
Explanation:
According to API 936 and TR 980,hydraulic bonded castablesshall not be allowed toair dry for more than 1 hourbefore the application of a curing compound. Prolonged exposure to air allows surface moisture to evaporate, leading to potential surface cracking and weak zones. Early application of curing compounds preserves internal hydration processes, which are essential for strength development.
Reference:
API TR 980 -Installation and Dryout, Section on hydraulic bonded castables: "Application of curing compound must occur within 1 hour of form removal or exposure."
NEW QUESTION # 27
Refractory samples cast during the mock-up are cured for a minimum of:
- A. 18 hours.
- B. 8 hours.
- C. 24 hours.
- D. 12 hours.
Answer: C
Explanation:
Mock-up installations serve as a qualification tool to verify that the installation procedures, personnel, and equipment can consistently meet quality standards. API 936 stipulates that refractory samples cast during the mock-up must becured for a minimum of 24 hoursbefore demolding or further processing. This curing period ensures full initial set and adequate strength development of the castable.
Failure to meet this curing requirement can result in incomplete hydration, premature cracking, or misleading performance test results. The 24-hour period allows for optimal moisture retention and chemical reaction completion in hydraulic-bonded castables.
Reference:
API Std 936, Section 6.3.3 - "Samples cast during the mock-up shall be cured in accordance with manufacturer's recommendations but not less than 24 hours under standard conditions."
NEW QUESTION # 28
The selected compression test section of the specimen for the CCs test shall be free from
- A. Other obvious defects
- B. All of the above
- C. cCracks
- D. Chipped surfaces
Answer: B
NEW QUESTION # 29
Enclosure inside the top head of a reactor or regenerator vessel which supports the cyclones and in which gases exiting the cyclone outlets are collected is called
- A. None of the above
- B. Riser of FCCU
- C. Plenum of FCCU
- D. Cyclone of FCCU
Answer: C
NEW QUESTION # 30
Test panels for pneumatic gunning are inclined above the horizontal at an angle of
- A. None of the above
- B. 30?
- C. 45?
- D. 60?
Answer: C
NEW QUESTION # 31
Maximum allowable crack length, visible on the surface of a dense firebrick, is:
- A. 1/4 in. (6 mm)
- B. 1/2 in.(12 mm)
- C. 3/8 in. (10 mm)
- D. 3/4 in. (19 mm)
Answer: B
Explanation:
API Std 936 defines crack length acceptance as follows:
"Surface cracks in dense firebrick shall not exceed 1/2 in. (13 mm) in length and shall not extend through the thickness of the brick."
- API Std 936, Section 8.3.3
Therefore, Option C is the correct maximum allowable length for a visible crack on firebrick.
NEW QUESTION # 32
Refractory failure mechanisms are.
- A. Overheating and chemical attack
- B. All of the above
- C. Thermal shock and mechanical abuse
- D. Erosion and corrosion
Answer: B
NEW QUESTION # 33
During gunning, inclusion of rebound is minimized by which of the following techniques?
- A. Start at the lowest level and build up gradually to full thickness in an area not more than 10 ft² (1 m²)
- B. Start at the lowest level elevation and build up gradually to full thickness in complete rings
- C. Begin gunning at the lowest level and work around to full thickness in a spiral pattern
- D. Cover all areas up to 1/2-in (13 mm) thick stud tip thickness before building to full thickness
Answer: A
Explanation:
To minimize rebound during gunning, API TR 980 clearly instructs to:
"Begin at the lowest level of the installation and build up gradually to full thickness in a small area of approximately 10 ft² (1 m²), avoiding sweeping motions."
- API TR 980, Section 4.3.4
This method prevents rebound contamination and cold joints that could occur if a larger area is covered too quickly or in an uncontrolled pattern.
Therefore, Option C is correct, and Options A, B, and D are incorrect according to best practices outlined in API TR 980.
NEW QUESTION # 34
Blanket, Module, Bulk paper, rope, and vacuum formed shaped are:
- A. Unshaped refractory
- B. All of the above
- C. Refractory fibers
- D. Shaped refractory
Answer: C
NEW QUESTION # 35
Which of the following is the inspector responsible for?
- A. Hammer testing newly installed linings
- B. Qualification testing
- C. Providing compliance data sheets
- D. Testing water to be used
Answer: A
Explanation:
Theinspector's responsibilities, as defined in API 936, include visual and mechanical inspection of installed linings.Hammer testingis one such non-destructive method used to detect delamination, voids, and rebound areas by listening for variations in sound. It is a practical method during and after installation.
Other tasks like providing compliance documentation or water testing are typically done by the contractor or laboratory personnel.
Reference:
API Std 936, Section 7.1 - "Inspectors shall perform hammer testing as part of surface inspection to detect voids and delamination."
NEW QUESTION # 36
An alternative to wire mesh baskets is a panel with enclosed sides when the:
- A. samples are cut with an abrasive medium
- B. dimensions are greater than 18 in. (450 mm) * 18 in. (450 mm) * 4 in. (100 mm)
- C. samples are cut from the edge of the panels
- D. dimensions are less than 18 in. (450 mm) * 18 in. (450 mm) * 4 in. (100 mm)
Answer: B
Explanation:
API 936 allows for the use oftest panels with enclosed sidesinstead of mesh basketswhen the dimensions exceed 18 in. x 18 in. x 4 in.This substitution provides adequate confinement and stability for larger samples during casting and curing, helping maintain uniformity and representative test integrity.
Wire mesh baskets are typically preferred for smaller, lighter samples, but for larger mock-ups or when vibration is involved, fully enclosed forms prevent edge erosion and deformation during casting and handling.
Reference:
API Std 936, Section 7.3.1.1 - "For samples greater than 18 in. × 18 in. × 4 in. (450 mm × 450 mm × 100 mm), solid-sided molds may be used instead of wire mesh baskets."
NEW QUESTION # 37
The effective diameter of metal fiber is
- A. None of the above
- B. 0.3 - 0.6 mm
- C. 0.4 - 0.8mm
- D. 0.2 - 0.3mm
Answer: B
NEW QUESTION # 38
A layer coat of refractory lining that is applied to an existing lining in an attempt to extend the lining's life is known as:
- A. overlay
- B. buttercoat
- C. paint
- D. overspray
Answer: A
Explanation:
The term "overlay" is defined in refractory terminology as:
"Overlay: A layer of refractory material applied over an existing lining, generally to extend service life or repair localized damage."
- API TR 980, Section 2, Definitions
The other terms do not carry this specific meaning in the context of refractory maintenance.
NEW QUESTION # 39
Refractory lined pipe used for the transport of hot particulate medium and gases between process vessels is called
- A. None of the above
- B. Standpipe of FCCU
- C. Transfer line of FCCU
- D. Fractionator of FCCU
Answer: C
NEW QUESTION # 40
To compose a sample for the CCS test from an equivalent number of refractory shapes the specimen should be
- A. None of the above
- B. At least four
- C. At least three
- D. At least five
Answer: D
NEW QUESTION # 41
A natural or synthetic mineral theoretically consisting solely of alumina (Al2O3), specific gravity 4.00 - 4.02, melting point 3720?F. (2050? C) Hardness 8.8 is called
- A. None of the above
- B. Mica
- C. Kaolin
- D. Corundum
Answer: D
NEW QUESTION # 42
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