100+ Free Tank Vessel-Assistant (DL) Practice Questions
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Key Facts: Tank Vessel-Assistant (DL) Exam
50
Multiple-choice questions in module Q456 (TK01)
USCG NMC Q456 sample exam
70%
Minimum passing score
USCG NMC
Dec 17, 2024
Date the endorsement was renamed Tank Vessel-Assistant
Final rule USCG-2021-0834
8%
Maximum oxygen by volume for an inerted cargo tank
Inert gas system requirements
125%
IG capacity versus combined cargo pump discharge rate
Inert gas system requirements
90 days
Tankship deck service for one exam-eligibility path
46 CFR 13.401(e)(2)
Aug 26, 2025
Last update of the official Q456 sample exam
USCG NMC
The USCG Tank Vessel-Assistant (Dangerous Liquids) exam is taken by mariners qualifying to assist with cargo transfers on tankships and tank barges. It is the single Part 13 tankerman endorsement with an NMC written test: module Q456 (code TK01), 50 multiple-choice questions, 70% to pass, in about 1.5 to 2 hours. Content follows Table 1 to 46 CFR 13.121(e): tanker types and arrangement; cargo piping, valves, pumps, loading and discharge sequence, tank cleaning, purging, gas-freeing, and inerting; physical and chemical properties such as flash point, vapor pressure, cargo grades, explosive limits, and electrostatic charge; hazards of flammability, toxicity, and reactivity with controls including inert gas, ventilation, gas testing, and SDS; safety equipment and PPE, enclosed-space entry, hot work, and firefighting; and pollution prevention, spill response, and emergency shutdown. The endorsement was renamed from Tankerman-Assistant by final rule effective December 17, 2024, and the NMC sample exam was last updated August 26, 2025.
Sample Tank Vessel-Assistant (DL) Practice Questions
Try these sample questions to test your Tank Vessel-Assistant (DL) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1When stripping a cargo tank, what is the most likely result of excessive air entering the suction line?
2How can you determine which grades of cargo a tank vessel is permitted to carry?
3Which category of operation causes the most frequent incidents of oil pollution during tanker operations?
4To reduce the accumulation of static electricity when loading petroleum products into a tank, you should ________.
5How should pinching of a cargo hose between the vessel and the dock be prevented during a transfer?
6Under U.S. regulations, no person may transfer oil to or from a vessel unless which condition is met?
7Who enforces the U.S. pollution regulations that apply to ships?
8Which statement best describes the flash point of a liquid?
9U.S. regulations require a pre-transfer conference before starting an oil transfer. Who must be in attendance?
10What is the maximum allowable oxygen content within a ship's cargo tanks, inert gas piping, and vapor recovery system that is considered inerted?
About the Tank Vessel-Assistant (DL) Exam
The Tank Vessel-Assistant (Dangerous Liquids) endorsement, renamed from Tankerman-Assistant by final rule USCG-2021-0834 effective December 17, 2024, authorizes a mariner to assist with cargo transfer functions on tankships and tank barges carrying dangerous liquids. It is the only Part 13 tankerman endorsement that requires an NMC written examination; the various person-in-charge endorsements are course-based. The exam is module Q456 (exam code TK01): 50 multiple-choice questions with a 70% passing score. Eligibility under 46 CFR 13.401(e)(2) includes 90 days of deck service on a qualifying tank vessel followed by the professional exam.
Questions
50 scored questions
Time Limit
Approximately 1.5 to 2 hours
Passing Score
70%
Exam Fee
MMC evaluation, exam, and issuance fees apply; confirm current amounts with the NMC (U.S. Coast Guard National Maritime Center (NMC))
Tank Vessel-Assistant (DL) Exam Content Outline
Tanker Construction and Arrangement
Tank vessel and tank barge types, general arrangement, cofferdams, double hull, pumproom location, segregated ballast tanks.
Cargo Operations and Equipment
Piping, valves, cargo pumps and stripping, hoses and couplings, loading and discharge sequence, trim, ullage and innage gauging, sampling, topping off.
Physical and Chemical Properties
Flash point, Reid vapor pressure and volatility, cargo grades A-E, lower and upper explosive limits, electrostatic charge and relaxation time.
Inert Gas Systems
Inerting principle and oxygen limits (5% supply, 8% tank), 125% capacity, scrubber, deck water seal, alarms and safeguards, pressure control.
Hazards, Safety and Enclosed Space
Flammability, toxicity (H2S, benzene), reactivity, sources of ignition, gas testing, enclosed-space entry, hot work, PPE, firefighting with foam.
Pollution Prevention and Regulations
Person in charge, pre-transfer conference, Declaration of Inspection, scupper plugs and containment, spill response and reporting, Oil Record Book.
How to Pass the Tank Vessel-Assistant (DL) Exam
What You Need to Know
- Passing score: 70%
- Exam length: 50 questions
- Time limit: Approximately 1.5 to 2 hours
- Exam fee: MMC evaluation, exam, and issuance fees apply; confirm current amounts with the NMC
Keys to Passing
- Complete 500+ practice questions
- Score 80%+ consistently before scheduling
- Focus on highest-weighted sections
- Use our AI tutor for tough concepts
Tank Vessel-Assistant (DL) Study Tips from Top Performers
Frequently Asked Questions
What is the Tank Vessel-Assistant (Dangerous Liquids) endorsement?
It is the USCG endorsement, renamed from Tankerman-Assistant by final rule effective December 17, 2024, that authorizes a mariner to assist with dangerous-liquid cargo transfers on tankships and tank barges.
Is there a written Coast Guard exam for this endorsement?
Yes. It is the only Part 13 tankerman endorsement requiring an NMC written exam: module Q456, exam code TK01, with 50 multiple-choice questions. All person-in-charge tankerman endorsements are course-based instead.
How many questions are on the exam and what score do I need?
The Q456 module has 50 multiple-choice questions, and you must score 70% or higher to pass, completed in roughly 1.5 to 2 hours.
What are the eligibility requirements?
Under 46 CFR 13.401(e)(2), one path is 90 days of deck service on a tankship or self-propelled tank vessel certificated to carry dangerous liquids, followed by the professional examination; an approved tankerman course is an alternative path.
What topics does the exam cover?
Per Table 1 to 46 CFR 13.121(e): tanker construction, cargo operations, physical and chemical properties, inert gas systems, hazards and safety including enclosed-space entry, and pollution prevention and transfer regulations.
What oxygen levels are tested for inert gas?
Inert gas delivered to the main must not exceed 5% oxygen by volume, and a cargo tank is considered inerted when its oxygen content is at or below 8% by volume.
Where is the official sample exam?
The NMC publishes the Q456 Tankship Dangerous Liquids sample exam (last updated August 26, 2025) on the dco.uscg.mil examinations pages; studying it shows the real question style.