Resit

Question 1

What are the hazards associated with Chemical carriers?

Answer 1

• Fire hazard.
• Health, defined by corrosive effects on the skin in the liquid state & toxic.
• Reactivity hazard.
• Marine pollution.

Question 2

What are the survey requirements for a chemical tanker?

Answer 2

1. Initial survey before the ship is put in service or before the International Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk is issued for the first time.
2. A renewal survey specified by the administration, but not exceeding 5 years.
3. An intermediate survey within 3 months before or after the second anniversary date or within 3 month before or after the third anniversary date of the Certificate.
4. An annual survey within 3 months before or after each anniversary date of the Certificate.
5. Additional survey, either general or partial according to the circumstances, shall be made when required whenever any important repairs or renewals are made.

Question 3

What is a type 1 chemical tanker?

Answer 3

A tanker which is intended to transport products with very severe environmental and safety hazards which require maximum preventive measures to preclude an escape of such cargo.

Question 4

What is a type 2 chemical tanker?

Answer 4

A tanker intended to transport products with appreciably severe environmental and safety hazards which require significant preventive measures to preclude an escape of such cargo.

Question 5

What is a type 3 chemical tanker?

Answer 5

A tanker intended to transport products with sufficiently severe environmental and safety hazards which require a moderate degree of containment to increase survival capability in a damaged condition.

Question 6

What is the standard damage requirements for a type 1 chemical tanker?

Answer 6

The tanker shall be assumed to sustain damage anywhere in its length.

Question 7

What is the standard damage requirements for a type 2 chemical tanker?

Answer 7

• (Over 150 meters) The Tanker shall be assumed to sustain damage anywhere in its length except involving either of the bulkheads bounding a machinery space located aft.
• (Under 150 meters) The tanker shall be assumed to sustain damage anywhere in its length.

Question 8

What is the standard damage requirements for a type 3 chemical tanker?

Answer 8

• (Over 225 meters) The tanker shall be assumed to sustain damage anywhere in its length.
• (Between 125-225 meters) The tanker shall be assumed to sustain damage anywhere in its length except involving either of the bulkheads bounding a machinery space located aft.
• (Under 125m) The tanker shall be assumed to sustain damage anywhere in its length except involving damage to the machinery space when located aft. However, the ability to survive flooding of the machinery space shall be considered by administration.

Question 9

What are the damage assumptions with a type 1 tanker?

Answer 9

• Form the side shell plating, the transverse damage should not exceed B/5 or 11.5 meters (measured inboard from the side at right angles to the centreline at the level of the summer load line).
• The vertical extent of damage being B/15 or 6 meters, whichever is less (measured form the moulded line of the bottom shell plating at the centreline) and nowhere near less than 760 mm from the shell plating. (this does not apply to slop tanks)

Question 10

What are the damage assumptions with a type 2 tanker?

Answer 10

• The vertical extent of damage being B/15 or 6 meters, whichever is less (measured form the moulded line of the bottom shell plating at the centreline) and nowhere near less than 760 mm from the shell plating. (this does not apply to slop tanks)

Question 11

What are the damage assumptions with a type 3 tanker?

Answer 11

No requirements.

Question 12

What is the maximum quantity per cargo tank on a type 1 ship?

Answer 12

1250m3

Question 13

What is the maximum quantity per cargo tank on a type 2 ship?

Answer 13

3000m3

Question 14

What documentation would be required to be sent prior to dry docking?

Answer 14

-Docking plan.
-General Arrangement Plan.
-Shell Expansion Plan.
-Fire Fighting Equipment Fire Protection Plan.
-Capacity Plan.
-Tank Plug Plan.
-Repair list/Dry Dock Specification.
-Stability plan.
-General Particulars.
-Gas Free Certificate.
-Cargo Plan and Manifest if docking with cargo onboard.
-Rigging Plan.
-Bilge/Ballast and cargo piping arrangement plan.
-Certificates in readiness for any surveys to be conducted.

Question 15

What is Annealing?

Answer 15

This consists of heating the steel at a slow rate to a temperature of say 850 °C to 950 °C, and then cooling it in the furnace at a very slow rate. The objective is to relieve any internal stresses, to soften the steel, or to bring the steel to a condition
suitable for a subsequent heat treatment.

Question 16

What is Normalising?

Answer 16

This is carried out by heating the steel slowly to a temperature similar to that for annealing and allowing it to cool in air. The resulting faster cooling rate produces a harder stronger steel than annealing, and also refines the grain size.

Question 17

What is quenching/hardening?

Answer 17

Steel is heated to temperatures similar to that for annealing and normalizing, and then quenched in water or oil. The fast cooling rate produces a very hard structure with a higher tensile strength.

Question 18

what is Tempering?

Answer 18

Quenched steels may be further heated to a temperature somewhat between
atmospheric and 680°C, and some alloy steels are then cooled fairly rapidly by
quenching in oil or water. The object of this treatment is to relieve the severe
internal stresses produced by the original hardening process and to make the material less brittle but retain the higher tensile stress.

Question 19

What is Stress reliving?

Answer 19

To relieve internal stresses the temperature of the steel may be raised so that no structural change of the material occurs and then it may be slowly cooled.

Question 20

What is High tensile steel?

Answer 20

Steel which has a greater ultimate tensile strength than mild steel.

Question 21

What are the advantages of high tensile steel?

Answer 21

• Structures can be made lighter.
• Ease of handling.
• The possibility to build larger prefabricated units.
• Saving in weld as it is thin material.

Question 22

What are the disadvantages of high tensile steel?

Answer 22

• The smaller allowable amount of wastage by corrosion.
• More likelihood for vibration to occur due to the lack of material mass.
• More care is required when welding.
• Increased bending and deflection as a result of hogging and sagging.

Question 23

What are the advantages of Aluminium alloys?

Answer 23

• Weight saving as significantly lighter than steel.
• Stability is improved caused by a lower centre of gravity when a ship is fitted with an aluminium super structure.
• Resistance to corrosion due to the inert layer of oxide which naturally forms on the surface.
• Non magnetic property.
• Notch toughness at low temperatures.

Question 24

What are the disadvantages of Aluminium alloys?

Answer 24

• Higher cost, it can be as much as 8-10 times the cost of mild steel.
• Low melting point, making it less fire resistant than steel.
• Galvanic corrosion as a result to direct contact with steel.
• Excessive vibration due to lack of material mass.

Question 25

What are the advantages stainless steel?

Answer 25

- High strength. - Bright colour as it maintains it appearance. - Corrosion resistant qualities due to containing chromium.

Question 26

What are the disadvantages stainless steel?

Answer 26

- Weld decay. - Pitting corrosion.

Question 27

What is the penetrant method for stress testing?

Answer 27

The surface to be inspected must be cleaned and dried. The surface of the material is heated to about 90ºC and then the penetrant liquid is sprayed or 'swabbed' on to the surface which will seep into any cracks. After sufficient time has elapsed the excess penetrant is cleaned off the surface with warm water, the surface tension of the water being too high to allow it to enter the fine cracks, and the test surface is thoroughly dried. The test surface is then coated with a 'developer' such as a very fine powdered chalk. The component is then set aside and allowed to cool. As the coated surface cools, it contracts and the penetrant tends to be squeezed out of any cracks, so the chalk layer will become stained, thus revealing the presence of any cracks (iii). Most penetrants of this type contain a scarlet dye, which renders the flaw immediately noticeable.

Question 28

What is the magnetic dust method for stress testing?

Answer 28

The aim of the process is to saturate the component with magnetic lines of force. The lines of force pass very easily through a good conductor such as metal, however, in air they repel each other to the extent that they spread apart as shown (i). Thus, on meeting a gap or other discontinuity in the conducting material at or just below the surface, the lines of force spread outwards ((i) and (ii)). If fine magnetic iron dust is sprinkled on to the surface of the component, it will stick to the surface of the component where the lines of force break out, thus revealing the site of the fault. Alternatively, the magnetised component can be placed in paraffin containing a suspension of tiny iron particles. The particles will be attracted to the surface of the component at any points where, due to the presence of a fault, lines of force cut through. Sensitivity can be improved by coating the surface to be treated with a carrier liquid containing magnetic particles which have been treated with a fluorescent compound. The surface is then examined under UV light in a dark room.

Question 29

How is radiography used to detect stresses in materials?

Answer 29

The principle of X-ray inspection depends on the ability of photographic film to be darkened by electro-magnetic radiation, so that X-rays have the same effect on photograph film as does visible light. The X-rays are allowed to pass through the component under examination so that they fall on to a piece of photographic film contained in an envelope which prevents the ingress of visible light. Since the metal will absorb X-rays readily, the intensity of radiation reaching the film will be reduced by increased thickness of metal. Similarly, any defects will allow very small zones of radiation of greater intensity to reach the film, forming darker zones on the developed film. Defects within the material can be very accurately identified by X-ray techniques

Question 30

How is ultrasonic used to detect stresses in materials?

Answer 30

The figure represents the principles of ultrasonic testing. A probe containing a quartz crystal which can both transmit and receive high frequency vibrations is passed over the surface to be tested. The probe is connected to an amplifier, which converts and amplifies the signal, before it is recorded on a cathode-ray tube. Under normal conditions the vibrations will pass from the probe, unimpeded through the metal, and be reflected from the bottom inside surface at B back to the probe, which also acts as a receiver. Both the transmitted pulse and its echo are recorded on the cathode-ray tube, and the distance, T1, between the 'blips' is proportional to the thickness, T, of the test material. If any discontinuity is encountered, such as a blowhole, D, then the pulse is interrupted, and reflected back as indicated. Since this echo returns to the receiver in a shorter time, an intermediate 'blip' appears on the cathode-ray tube. It's position relative to the other 'blips' indicates the relative distance of the fault below the surface. The nature of the echo depends upon the type of fault.

Question 31

What are the regulations involved in Structural fire protection?

Answer 31

1 - Application. 2 - Fire Safety Objectives and Functional Requirements. 3 - Definitions. 4 - Probability of Ignition. 5 - Fire Growth Potential. 6 - Smoke Generation Potential and Toxicity. 7 - Detection and alarm. 8 - Control of Smoke Spread. 9 - Containment of Fire. 10 - Fire-Fighting. 11 - Structural Integrity. 12 - Notification of Crew and Passengers. 13 - Means of escape. 14 - Operational Readiness and Maintenance. 15 - Instructions, On-Board Training and Drills. 16 - Operations. 17 - Alternative Design and Arrangements. 18 - Helicopter facilities. 19 - Carriage of Dangerous Goods 20 - Protection of vehicle, Special category and Ro Ro Spaces.

Question 32

What design and construction materials are considered to limit damage to ships?

Answer 32

- Scantlings. - Grade of steel. - Design shape of openings and maintenance of continuity of strength.

Question 33

What structural components/features are used to limit damage to ships?

Answer 33

- Frame spacing. - Stringers, beams, beam knees brackets. - Shell plating. - Raised superstructures. - Hatch coamings and hatch lid type/ material and construction. - Bow height. - Double bottom depth and structure. - Double hull arrangements. - Watertight and weathertight doors. - Fire category of bulkheads and fire doors.

Question 34

What is a class 'A' division?

Answer 34

- A division which shall be constructed of steel or other equivalent material. - Shall be insulated with non combustible materials. - The average temperature on the nonexposed side will not rise more than 139 degree/C. - The average temperature of any joint will not rise above 180 degree/C. - Three Classes: 60, 30, 15

Question 35

What is a class 'B' division?

Answer 35

- Shall be constructed as to be capable of preventing the passage of flame to the end of the first half hour of the standard fire test. - The average temperature on the nonexposed side will not rise more than 139 degree/C. - The average temperature of any joint will not rise above 225 degree/C. - Two classes: 15, 0