AME Flashcards

AME Unit 1 Alloys, Metals, Stainless Steel, Materials of Components

With reference to ship’s side valves:

state, with reasons, THREE suitable materials.

B. Bronze, stainless steel, and ductile iron: Due to their combination of strength, corrosion resistance, and durability.

Question: Why is grey cast iron generally unsuitable for ship's side valves?

D. Grey cast iron is brittle and susceptible to fracture under marine conditions.

Question: What are the three main constituents of austenitic stainless steel and their approximate percentage compositions?

A. Iron (60-70%), Chromium (16-18%), Nickel (8-10%)

Question: What is stainless steel and what are its two main constituents and their approximate percentages?

A. Stainless steel is an iron alloy containing at least 10% chromium and 8% nickel.

Question: What is one common use of martensitic stainless steel?

B. Surgical instruments

Question: What is the main difference between stainless steel grades 304 and 316, and how is it achieved?

C. 316 has added molybdenum, enhancing corrosion resistance.

Question: With reference to cupro-nickel, what is the approximate percentage composition and a common application on board a marine vessel?

B. 90% copper, 10% nickel; used for heat exchanger tubes  

Question: Which material is most suitable for a centrifugal pump impeller in marine applications and why?

C. Stainless steel: Due to its high strength and corrosion resistance.

Question: Which material is most suitable for a cylinder head of a small auxiliary engine on a marine vessel?

A. Cast iron: Due to its high strength and heat resistance.  

Question: Which material is most suitable for a seawater-cooled heat exchanger on a marine vessel and why?

B. Copper-nickel alloy: Due to its excellent corrosion resistance and heat transfer properties.

Question: What is an alloy and why are they used?

B. An alloy is a mixture of two or more metals or a metal and other elements. Alloys are used to create materials with specific properties not found in pure metals.

Question: What is one common use of ferritic stainless steel?

B. Kitchen sinks  

Question: Which of the following pairs correctly match a stainless steel grade (304 or 316) with two typical applications found on a modern marine vessel?

B. 304: Interior fittings, railings; 316: Hull components, bilge pumps

Question: Which material is most suitable for a large motor marine vessel propeller and why?

B. Bronze: Due to its corrosion resistance and good bearing properties.

Question: With reference to solder, what is the approximate percentage composition and a common application on board a marine vessel?

C. 63% tin, 37% lead; used for electrical connections  

Question: How do the mechanical properties of steel change with increasing carbon content?

B. Strength increases while ductility decreases with increasing carbon content.

Question: Which of the following are common alloying elements used in steel production?

A. Carbon, silicon, manganese, chromium, nickel, and molybdenum.

Question: What is one common use of austenitic stainless steel?

B. Kitchen cutlery

Question: With reference to admiralty brass, what is the approximate percentage composition and a common application on board a marine vessel?

B. 70% copper, 29% zinc, 1% tin; used for heat exchanger tubes

Question: With reference to aluminium bronze, what is the approximate percentage composition and a common application on board a marine vessel?

A. 90% copper, 10% aluminum; used for propeller blades

Question: With reference to duralumin, what is the approximate percentage composition and a common application on board a marine vessel?

C. 93% aluminum, 4% copper, 3% magnesium; used for superstructure components

Question: Which material is most suitable for a 300mm diameter seawater cooling pipe on a marine vessel and why?

B. Copper-nickel alloy: Due to its excellent corrosion resistance and heat transfer properties.
1 / 22

AME Unit 2 Heat treatments, Annealing Normalising

Question: With reference to case hardening steel components, describe a simple onboard process.

B. Flame hardening.

Question: With reference to aluminum, explain what is meant by work hardening.

C. The increase in strength of aluminum due to plastic deformation.

Question: With reference to the case hardening of bearing journals, describe the nitriding process.

C. A chemical process where nitrogen is diffused into the surface of the workpiece to form a hard compound layer.  

Question: With reference to aluminum, describe how it could be annealed on board a vessel.

B. By heating the aluminum to a specific temperature, holding it there, and then cooling it slowly.

Question: With reference to the heat treatment of steel, which steels are best suited for annealing?

B. Low-carbon steels

Question: Describe the heat treatment process a valve spring would undergo, stating the reasons for the processes.

A. Annealing to improve ductility, followed by hardening to increase strength.

Question: Explain how the properties of steel are modified by its carbon content.

C. Increasing carbon content increases strength but decreases ductility.

Question: With reference to the hardening of steel as a heat treatment process, what changes occur in the mechanical properties and internal structure?

B. Increased hardness, decreased ductility, and formation of martensite.

Question: Describe the heat treatment process a crankshaft would undergo, stating the reasons for the processes.

C. Hardening to increase wear resistance, followed by tempering to improve toughness.

Question: With reference to the case hardening of steel components, describe the changes that occur with this process.

B. Increased hardness at the surface, while maintaining a tough core.

Question: With reference to case hardening steel components, describe solid pack carburizing.

C. A process where the workpiece is heated in a carbon-rich environment to introduce carbon into the surface layer.

Question: Explain hardening.

B. Hardening is a heat treatment process to increase hardness and reduce ductility.

Question: With reference to aluminum, describe the internal changes when it becomes work hardened.

B. Grain size decreases and elongated grains form, leading to increased strength.

Question: With reference to the case hardening of bearing journals, describe the induction hardening process.

B. A heat treatment process where only the surface of the workpiece is rapidly heated using high-frequency currents, followed by quenching.

Question: Explain normalizing.

C. Normalizing is a heat treatment process that refines the grain structure and improves toughness.

Question: With reference to tempering as a heat treatment of steel, explain the changes in mechanical properties and the internal structure.

C. Increased toughness, decreased brittleness, and refinement of microstructure.

Question: With reference to aluminum, state the effect work hardening has on its properties.

B. Increases strength, decreases ductility.

Question: With reference to the case hardening of bearing journals, explain why this process may be carried out.

C. To increase the wear resistance of the journal surface.

Question: Describe the heat treatment process a used copper washer would undergo, stating the reasons for the processes.

A. Annealing to relieve stresses and improve ductility.

Question: Explain annealing.

B. Annealing is a heat treatment process that softens the metal and increases ductility.

Question: With reference to the case hardening of steel components, explain why it may be required.

C. To enhance the wear resistance of the component's surface.  
1 / 21

AME Unit 3 Fatigue and Failure

With reference to fatigue failure of components, which of the following correctly describes the three stages of fatigue failure.

A) Crack Initiation, Crack Growth, Rapid Fracture Stage 1: Microcracks form at stress concentrators (e.g., surface defects or grain boundaries). Stage 2: The crack slowly propagates through the material under cyclic loading. Stage 3: The crack grows rapidly, leading to sudden failure of the component.

Which of the following describes two destructive tests that a sample of metal intended for the manufacture of a propeller shaft would undergo before being accepted by a classification society?

A) Tensile Test and Impact Test

Question: With reference to the hull of a vessel: state the effect of fatigue on the hull material

B. Gradual weakening and cracking of the material.

With reference to fatigue failure of components, which of the following methods can be used on board a marine vessel to limit the possibility of fatigue failure to a propeller shaft?

A) Regular Lubrication, Dynamic Balancing, Shaft Alignment Ensure the propeller shaft is well-lubricated, dynamically balanced to minimize vibrations, and properly aligned with the engine and bearings.

Which of the following lists four methods for non-destructive crack detection?

A) Ultrasonic Testing, Magnetic Particle Testing, Dye Penetrant Testing, X-ray Inspection

How is a Brinell hardness test carried out?

A) A hardened steel or carbide ball is pressed into the material's surface under a specific load, and the diameter of the indentation is measured to calculate hardness.

With reference to fatigue failure of components, how does the surface appearance of a fatigue fracture typically present?

D) Beach marks and striations: The fracture surface shows concentric rings (beach marks) and fine lines (striations) radiating from the crack initiation site.

What is a typical safety coefficient designed into a propeller shaft of a superyacht?

B) 2.0

With reference to fatigue failure of components, how is material fatigue testing typically carried out in a laboratory?

C) Cyclic Loading Testing: The material is subjected to repeated cycles of loading and unloading, and the number of cycles to failure is recorded.

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.

How can false brinelling be reduced in practice?

A) By using vibration dampeners or isolators to minimize vibrations during storage or transportation.

With reference to a ball race bearing, what does the term "brinelling" refer to?

A) Permanent deformation of the raceway surface due to excessive load, resulting in indentations from the rolling elements.

What is the term "safety coefficient" (factor of safety), and why is it required?

A) A numerical value used to account for uncertainties in material properties and loading conditions, ensuring that structures can support loads beyond the maximum expected loads.

With reference to the installation of copper pipes in engine cooling systems, which of the following are three possible causes for their premature failure?

A) Corrosion, Overheating, Vibration Fatigue

With reference to the installation of copper pipes in engine cooling systems, which of the following are four recommendations for their installation?

A) Ensure Proper Support and Alignment, Use Correct Fittings, Avoid Sharp Bends, Apply Appropriate Insulation

With reference to a ball race bearing, what does the term "false brinelling" refer to?

A) Surface wear on the raceway caused by vibration and relative motion between stationary rolling elements and raceways when the bearing is not rotating.

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.
1 / 17

AME Unit 4 Youngs modulus, Hardness, Stress, UTS

What is the ultimate tensile strength?

C) The maximum stress a material can endure before fracturing or breaking.

What is the definition of shear stress?

 

C) The internal resistance of a material to forces that twist or slide layers past each other, calculated as the force parallel to the surface divided by the area.

With reference to stresses within engineering materials, what is the definition of compressive stress?

 

C) The internal resistance of a material to forces that push or compress it together, calculated as the force applied per unit area.

What is toughness of a material?

 

B) The ability of a material to absorb energy and deform plastically without breaking.

What is malleability?

 

B) The ability of a material to be hammered or pressed into thin sheets without breaking.

Which component in a 4-stroke diesel engine has a maximum recommended service life due to constant cyclic stress?

C) Connecting Rods

What is the definition of tensile stress?

 

B) The internal resistance of a material to forces that pull it apart, calculated as the force applied per unit area.

With reference to stresses within engineering materials, what is the definition of tensile stress?

A) The internal resistance of a material to forces that pull it apart, calculated as the force applied per unit area.

What is the definition of proof stress?

 

B) The stress at which a material exhibits a specific amount of plastic deformation, often used to estimate yield strength.

Which of the following factors may influence the safety coefficient in operation? (Select two)

A) Material fatigue and environmental conditions, C) Operational load conditions and manufacturing tolerances

What is the yield point?

 

A) The point on a stress-strain curve where the material starts to experience permanent deformation.

What is the 0.1% proof stress test?

 

A) A test to determine the stress at which a material exhibits 0.1% plastic deformation, used to measure its yield strength.

Which of the following are components within a diesel engine that are subject to tensile stress? (Select two)

 

B) Connecting Rods, C) Cylinder Head Bolts

What is the ultimate tensile strength?

 

D) The maximum stress a material can withstand before fracturing or breaking.

What is the limit of proportionality?

 

D) The point on a stress-strain curve where the stress and strain are directly proportional, and beyond which the material begins to exhibit non-linear behavior.

What is the definition of hardness in materials science?

 

B) The resistance of a material to deformation, indentation, or scratching.

What is the definition of the safety coefficient (factor of safety)?

 

D) The ratio of the design load to the maximum load a structure can support, providing a margin of safety against failure.

What is the definition of work hardening?

 

B) The increase in a material's hardness and strength as a result of plastic deformation, such as stretching or bending.

What is yield stress?

 

B) The stress at which a material begins to plastically deform, marking the transition from elastic behavior.

What is the definition of Young's modulus?

 

C) The measure of a material's stiffness or resistance to elastic deformation, calculated as the ratio of tensile stress to tensile strain within the elastic limit.

What is ductility?

 

C) The ability of a material to be drawn into thin wires or stretched without breaking.

What is the definition of plasticity in materials?

 

C) The ability of a material to permanently deform without breaking when a force is applied.

What is the definition of shear stress?

 

C) The internal resistance of a material to forces that twist or slide parallel to the surface, calculated as the force applied parallel to the area divided by that area.

What is the definition of Young's modulus?

 

C) The ratio of tensile stress to tensile strain in a material, describing its ability to resist deformation under tensile loading.

What is brittleness?

 

C) The tendency of a material to fracture or break with little plastic deformation when subjected to stress.

What is ductile cast iron?

 

C) Cast iron that has been alloyed with silicon and other elements to improve its ductility and tensile strength, allowing it to deform without breaking.
1 / 26

AME Unit 5 GRP (fibreglass)

Which of the following are three causes of osmotic blisters in glass reinforced plastic (GRP) hulls?

 

A. Inadequate gelcoat thickness, high moisture content in the hull, and poor bonding between laminate layers.

When treating a single osmotic blister on a glass reinforced plastic (GRP) hull, which of the following procedures is most appropriate?

C. Cut away the blistered area entirely, clean and dry the exposed surface, fill the void with a marine-grade filler, and then sand, prime, and repaint the area.

Which of the following are two effective methods for detecting delamination in glass reinforced plastic (GRP) hulls during service?

 

A. Tapping the hull with a metal hammer to listen for changes in sound and using a moisture meter to measure the moisture content.

Which of the following are two possible actions to take if root whitening is discovered in a glass reinforced plastic (GRP) hull?

 

A. Reapply a new gelcoat layer and perform a thorough inspection to ensure UV protection.

Which of the following are three causes of delamination in glass reinforced plastic (GRP) hulls?

 

A. Excessive moisture ingress, poor resin curing, and impact damage.

Which of the following are three design problems that can lead to stress cracking in glass reinforced plastic (GRP) hulls?

 

A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.

How does resin infusion molding help virtually eliminate the onset of osmosis in a GRP hull?

 

B) By creating a continuous, void-free barrier with improved fiber-to-resin ratio that reduces water absorption.

Which of the following best describes the full process for the treatment of a glass reinforced plastic (GRP) hull suffering from the effects of osmosis?

 

B. Remove any visible blisters by cutting them out, thoroughly clean and dry the exposed area, fill the void with a marine-grade filler, sand the surface smooth, apply a primer, and then repaint the hull to ensure protection.

What are some disadvantages of GRP (Glass Reinforced Plastic) hulls in service?

 

C) Potential for UV degradation and difficulty in repairs; higher initial cost compared to traditional materials.

What is the traditional method for the layup of a Glass Reinforced Plastic (GRP) hull?

B) Laying down multiple layers of glass fiber mat and resin in a mold, followed by a curing process, with each layer being hand-rolled to remove air bubbles.

Which of the following are three possible causes of delamination in glass reinforced plastic (GRP) hulls?

 

A. Excessive moisture ingress, poor adhesion between laminate layers, and impact damage.

What is the term "root whitening" in glass reinforced plastic (GRP) hull construction, and where is it most likely to occur?

 

A. Root whitening refers to a discoloration or fading of the gelcoat layer, most commonly occurring around the waterline and hull sections exposed to high UV radiation.

Which part of the underwater section of a glass reinforced plastic (GRP) hull is most commonly affected by osmotic blisters?

 

A. The keel and the areas around the bilge.

What is the process of resin infusion molding for the production of a Glass Reinforced Plastic (GRP) hull?

B) Placing dry glass fiber fabric in a mold, sealing the mold, and then injecting resin under vacuum pressure to infuse the fabric and cure the composite.

What are the advantages of resin infusion molding compared to traditional methods of construction?

 

B) Improved fiber-to-resin ratio, reduced air voids, better control over material properties, and enhanced structural integrity.

Which properties of glass fiber and resin make them suitable for the construction of a hull?

 

D) Glass fiber has high tensile strength and flexibility; resin provides good adhesion and low water absorption.

Which of the following methods is most effective for detecting osmosis in a glass reinforced plastic (GRP) hull during service?

 

C. Measuring the moisture content of the hull using a moisture meter and looking for raised, soft, or discolored areas that may indicate osmotic blistering.

Which of the following are two possible reasons for root whitening in glass reinforced plastic (GRP) hull construction?

 

A. Prolonged exposure to ultraviolet (UV) light and degradation of the gelcoat layer due to environmental conditions.

Which of the following best explains the process of osmosis in glass reinforced plastic (GRP) hulls and the formation of osmotic blisters in service?

B. Osmosis occurs when water molecules pass through the GRP laminate, entering voids and reacting with soluble materials within the laminate. This results in the build-up of pressure, causing the GRP layers to separate and form blisters.

Why is simply drying out a glass reinforced plastic (GRP) hull not a sufficient cure for the effects of osmosis?

 

A. Drying out the hull removes all moisture, but it leaves behind the weakened laminate and does not repair any structural damage caused by osmosis.

Which of the following are three causes of stress cracking in glass reinforced plastic (GRP) hulls?

 

A. Sharp corners or edges in the hull design, excessive weight concentration in specific areas, and insufficient reinforcement in high-stress zones.

Which of the following are two effective methods for repairing delamination in a sandwich construction glass reinforced plastic (GRP) hull?

 

C. Cut out the delaminated section, fill the cavity with a core material, and then cover with a new layer of laminate.
1 / 22

AME Unit 6 Carbon fibre

Which of the following are considered undesirable properties of carbon fiber for hull construction in marine applications?

 

A. High cost, high susceptibility to UV degradation, and potential for brittle failure.

What is vacuum bagging in the manufacture of carbon fiber components?

 

A. A process where a vacuum is applied to remove air and excess resin from the carbon fiber layup, ensuring a compact and void-free composite.

What is autoclave curing in the manufacture of carbon fiber components?

 

A. A process where carbon fiber components are heated under high pressure in an autoclave to cure the resin, which enhances the composite's strength and durability.

Which of the following are four properties of carbon fiber that make it desirable for marine fabrication?

 

A. High tensile strength, low weight, high stiffness, and excellent resistance to corrosion.

Which properties of carbon fiber make it suitable for hull construction in marine applications?

 

A. High strength-to-weight ratio, excellent corrosion resistance, low thermal conductivity, and high impact resistance.

What is resin transfer molding (RTM) in the manufacture of carbon fiber components?

 

A. A process where resin is injected into a closed mold containing carbon fiber layers, allowing the resin to saturate the fibers and then cure under pressure to form the final component.

How does the internal structure of carbon fiber contribute to its unique strength properties?

 

A. Carbon fibers have a crystalline structure with carbon atoms arranged in hexagonal lattices, which provides high tensile strength and stiffness.

How is the base raw material turned into usable carbon fiber?

 

A. The raw material is first spun into fibers, then stabilized through a chemical process, carbonized at high temperatures, and finally treated with a surface finish before being combined with a resin matrix.

Which of the following are necessary safety considerations when working with carbon fiber? (Select all that apply)

 

A. Wearing personal protective equipment (PPE) such as gloves and masks., B. Ensuring proper ventilation to avoid inhaling dust and fumes., C. Avoiding direct contact with resin chemicals and using appropriate protective measures.

Which of the following are considered undesirable properties of carbon fiber for mast construction in marine applications?

 

A. High cost, potential for brittle failure, and high susceptibility to UV degradation.

What are the advantages of using resin transfer molding (RTM) in the manufacture of carbon fiber components?

 

A. Provides high precision and consistency, allows for complex shapes and large parts, reduces labor costs, and enables efficient use of materials.

What are the advantages of using vacuum bagging in the manufacture of carbon fiber components?

 

A. Reduces air bubbles and voids, ensures even resin distribution, improves fiber-to-resin ratio, and helps in achieving a smoother surface finish.

What are the advantages of using autoclave curing in the manufacture of carbon fiber components?

 

A. Achieves high-quality curing with uniform temperature and pressure, reduces voids and air bubbles, enhances mechanical properties, and ensures consistent material performance.

Which properties of carbon fiber make it suitable for mast construction in marine applications?

 

A. High strength-to-weight ratio, high stiffness, excellent fatigue resistance, and low thermal expansion.

How are carbon fibers turned into a usable product?

 

A. Carbon fibers are first woven into fabric, then impregnated with resin, and finally cured in an autoclave to form a composite material.
1 / 15

AME Unit 7 Marine, Galvanic and Stess Corrosion

Which of the following lists four methods for non-destructive crack detection?

A) Ultrasonic Testing, Magnetic Particle Testing, Dye Penetrant Testing, X-ray Inspection

With reference to fatigue failure of components, how does the surface appearance of a fatigue fracture typically present?

D) Beach marks and striations: The fracture surface shows concentric rings (beach marks) and fine lines (striations) radiating from the crack initiation site.

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.

With reference to fatigue failure of components, which of the following correctly describes the three stages of fatigue failure.

A) Crack Initiation, Crack Growth, Rapid Fracture Stage 1: Microcracks form at stress concentrators (e.g., surface defects or grain boundaries). Stage 2: The crack slowly propagates through the material under cyclic loading. Stage 3: The crack grows rapidly, leading to sudden failure of the component.

With reference to the installation of copper pipes in engine cooling systems, which of the following are four recommendations for their installation?

A) Ensure Proper Support and Alignment, Use Correct Fittings, Avoid Sharp Bends, Apply Appropriate Insulation

How is a Brinell hardness test carried out?

A) A hardened steel or carbide ball is pressed into the material's surface under a specific load, and the diameter of the indentation is measured to calculate hardness.

Question: With reference to the hull of a vessel: state the effect of fatigue on the hull material

B. Gradual weakening and cracking of the material.

What is the term "safety coefficient" (factor of safety), and why is it required?

A) A numerical value used to account for uncertainties in material properties and loading conditions, ensuring that structures can support loads beyond the maximum expected loads.

With reference to the installation of copper pipes in engine cooling systems, which of the following are three possible causes for their premature failure?

A) Corrosion, Overheating, Vibration Fatigue

How can false brinelling be reduced in practice?

A) By using vibration dampeners or isolators to minimize vibrations during storage or transportation.

With reference to a ball race bearing, what does the term "brinelling" refer to?

A) Permanent deformation of the raceway surface due to excessive load, resulting in indentations from the rolling elements.

Which of the following describes two destructive tests that a sample of metal intended for the manufacture of a propeller shaft would undergo before being accepted by a classification society?

A) Tensile Test and Impact Test

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.

With reference to fatigue failure of components, which of the following methods can be used on board a marine vessel to limit the possibility of fatigue failure to a propeller shaft?

A) Regular Lubrication, Dynamic Balancing, Shaft Alignment Ensure the propeller shaft is well-lubricated, dynamically balanced to minimize vibrations, and properly aligned with the engine and bearings.

With reference to fatigue failure of components, how is material fatigue testing typically carried out in a laboratory?

C) Cyclic Loading Testing: The material is subjected to repeated cycles of loading and unloading, and the number of cycles to failure is recorded.

With reference to a ball race bearing, what does the term "false brinelling" refer to?

A) Surface wear on the raceway caused by vibration and relative motion between stationary rolling elements and raceways when the bearing is not rotating.

What is a typical safety coefficient designed into a propeller shaft of a superyacht?

B) 2.0
1 / 17

AME Unit 8 Welding, Mig Tig, oxy, explosion

What is lack of fusion in a weld produced using the covered electrode welding process?

 

A. A defect where there is inadequate bonding between the weld metal and the base metal, or between adjacent weld passes, resulting in a gap or separation that weakens the weld.

What are three disadvantages of using aluminum in vessel construction?

 

A. Limited resistance to saltwater corrosion, higher material cost, and lower structural strength compared to steel.

What are inclusions in a weld produced using the covered electrode welding process?

 

A. Defects where non-metallic materials, such as slag or oxide, are trapped within the weld metal, leading to weakened weld strength and potential for failure.

What is an undercut defect in a weld produced using the covered electrode welding process?

 

A. A defect where the weld metal has formed a concave groove along the edge of the weld, creating a depression that weakens the joint and can lead to crack formation.

Which welding/brazing/soldering process is best suited for attaching a stainless steel handrail to a steel hull, and why?

 

A. TIG Welding: Provides precise control and produces clean, high-quality welds with minimal spatter, making it ideal for welding stainless steel to steel due to its ability to handle different materials and produce strong, clean joints.

What is a crater defect in a weld produced using the covered electrode welding process?

 

A. A defect where a small, deep depression forms at the end of the weld bead due to improper stopping of the welding arc, leading to a weakened area that can be prone to cracking.

What is the TIG welding process?

 

A. TIG welding (Tungsten Inert Gas welding) involves using a tungsten electrode to create an electric arc between the electrode and the workpiece, with the weld area protected by an inert gas, usually argon or helium. The process may or may not include a filler rod, which is added separately to the weld pool.

What is the process of oxy-acetylene welding?

B. Oxy-acetylene welding uses a mixture of oxygen and acetylene gases to produce a high-temperature flame that melts the metal surfaces, allowing them to fuse together.

How does the gas metal arc welding (MIG) process work for welding mild steel?

 

A. MIG welding involves creating an electric arc between a consumable wire electrode and the workpiece, with a shielding gas to protect the weld from atmospheric contamination.

What is lack of penetration in a weld produced using the covered electrode welding process?

 

A. A defect where the weld metal does not fully penetrate the base metal, resulting in a shallow weld and poor fusion, which weakens the joint.

What are the particular problems associated with an aluminum superstructure when it is bonded to a steel hull?

 

A. The formation of galvanic corrosion due to the electrical difference between aluminum and steel, which can lead to accelerated degradation of the aluminum and potential structural issues.

What is porosity in a weld produced using the covered electrode welding process?

 

A. A defect where gas bubbles are trapped within the weld metal, resulting in a porous structure that weakens the weld and may cause a rough surface appearance.

What are three advantages of using steel in vessel construction?

 

B. Excellent weldability, high structural strength, and cost-effectiveness for large-scale construction.

What is an overlap defect in a weld produced using the covered electrode welding process?

 

A. A defect where the weld metal extends over the edge of the base metal without proper fusion, creating a pronounced ridge or lip that weakens the joint and can affect its strength.

Question:

Which welding/brazing/soldering process is best suited for attaching a brass flange to a stainless steel pipe, and why?

A. Brazing: Uses a filler metal with a lower melting point than the base metals, which can effectively join brass and stainless steel without melting the base materials and provides a strong, durable joint.

Why is it important to get the gas mixture correct in oxy-acetylene welding?

 

A. Correct gas mixture ensures that the flame temperature is high enough to melt the metal efficiently and produce a strong weld.

What are cracks in a weld produced using the covered electrode welding process?

 

A. Defects characterized by visible fissures or separations in the weld metal, caused by rapid cooling, high stresses, or improper welding parameters, which can significantly weaken the weld.

What are four conditions necessary for the preparation of steel surfaces prior to painting to ensure a good surface finish?

 

A. The surface must be clean and free of rust, oil, and grease; properly sanded to remove any old paint; dried completely before application; and primed with an appropriate primer.

What is spatter in a weld produced using the covered electrode welding process?

 

A. Small droplets of molten metal that are expelled from the weld pool and land on the surrounding area, often due to excessive heat or improper welding parameters.

Why is it not normal practice to join aluminum superstructures to a steel hull using conventional welding techniques?

 

A. Conventional welding techniques cannot effectively join aluminum and steel due to differences in melting points, which can lead to weak joints and potential structural failures.

Why is an explosion-welded joint considered superior to an insulated bolt joint for joining a steel hull to an aluminum superstructure?

 

A. Explosion welding provides a continuous, seamless joint with high strength and minimal thermal distortion, whereas an insulated bolt joint may suffer from mechanical weaknesses and potential galvanic corrosion.

What are three advantages and one limitation of gas metal arc welding (MIG) of mild steel?

 

C. Advantages: High-quality welds with less spatter, ability to weld in all positions, suitable for automation; Limitation: High equipment and consumable costs.

What are the advantages of TIG welding compared to other welding methods?

 

A. TIG welding provides high-quality welds with precise control over the heat and filler material, making it ideal for welding thin materials and producing aesthetically pleasing welds.

Question:

Which welding/brazing/soldering process is best suited for attaching a 1.0 mm steel section to a 10 mm thick deckhead plate, and why?

A. MIG Welding: Provides a good balance of speed and control, making it suitable for welding thin sections to thicker plates while offering consistent results and effective penetration.

What is slag inclusion in a weld produced using the covered electrode welding process?

 

A. A defect where non-metallic slag is trapped within the weld metal, creating inclusions that weaken the weld and can affect its strength and appearance.

What is a typical transition joint used to attach an aluminum superstructure to a steel hull?

 

A. A mechanical joint that uses a non-corrosive insulating material between the aluminum and steel, such as a plastic or rubber gasket, to prevent galvanic corrosion and ensure a secure connection.

Why is AC current preferred for TIG welding of aluminum?

 

A. AC current helps to clean the aluminum surface by alternating between positive and negative polarities, which removes oxides and improves the weld quality.

What are the design safety features and inspections to be carried out on the oxy-acetylene welding torch and cylinders before commencing welding?

 

A. Inspect for gas leaks, ensure pressure gauges are functional, check the integrity of hoses, and verify that regulators are properly calibrated.

Which welding/brazing/soldering process is best suited for joining two lengths of aluminium bronze seawater pipe with the same diameter, and why?

 

C. Brazing: Uses a filler metal with a lower melting point than the base metal, allowing for a strong bond between the aluminium bronze pipes without melting the base material.

Which welding/brazing/soldering process is best suited for re-attaching a section of a broken flange on a cast iron pump casing, and why?

 

A. Brazing: Utilizes a filler metal with a lower melting point than the base metal, which can effectively join cast iron without the need for high temperatures that could cause further damage to the pump casing.

What is the process of explosion welding, and how is it used to join a steel hull to an aluminum superstructure?

 

A. Explosion welding involves detonating a high-explosive charge to force two metal surfaces together, creating a strong bond without melting the metals. This process is suitable for joining dissimilar metals like steel and aluminum due to its ability to handle different material properties.

What maintenance should be carried out to ensure the continued structural integrity of a vessel with an aluminum superstructure attached to a steel hull?

 

A. Regular inspection and cleaning of joints to prevent galvanic corrosion, application of protective coatings to both aluminum and steel surfaces, and periodic replacement of anodes if used for cathodic protection.

What surface preparation is required for gas metal arc welding (MIG) of mild steel, and why?

 

A. The surface should be clean and free of rust, paint, oil, and other contaminants to ensure proper electrical contact and strong welds.
1 / 33

AME Unit 9 Probes, Thermistors, Sensors

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.

With reference to fatigue failure of components, how is material fatigue testing typically carried out in a laboratory?

C) Cyclic Loading Testing: The material is subjected to repeated cycles of loading and unloading, and the number of cycles to failure is recorded.

Question: With reference to the hull of a vessel, describe how fatigue stress occurs whilst in a seaway.

B. The hull experiences repeated cycles of loading and unloading due to wave action.

With reference to fatigue failure of components, how does the surface appearance of a fatigue fracture typically present?

D) Beach marks and striations: The fracture surface shows concentric rings (beach marks) and fine lines (striations) radiating from the crack initiation site.

Which of the following describes two destructive tests that a sample of metal intended for the manufacture of a propeller shaft would undergo before being accepted by a classification society?

A) Tensile Test and Impact Test

With reference to fatigue failure of components, which of the following methods can be used on board a marine vessel to limit the possibility of fatigue failure to a propeller shaft?

A) Regular Lubrication, Dynamic Balancing, Shaft Alignment Ensure the propeller shaft is well-lubricated, dynamically balanced to minimize vibrations, and properly aligned with the engine and bearings.

What is the term "safety coefficient" (factor of safety), and why is it required?

A) A numerical value used to account for uncertainties in material properties and loading conditions, ensuring that structures can support loads beyond the maximum expected loads.

With reference to a ball race bearing, what does the term "false brinelling" refer to?

A) Surface wear on the raceway caused by vibration and relative motion between stationary rolling elements and raceways when the bearing is not rotating.

With reference to a ball race bearing, what does the term "brinelling" refer to?

A) Permanent deformation of the raceway surface due to excessive load, resulting in indentations from the rolling elements.

Question: With reference to the hull of a vessel: state the effect of fatigue on the hull material

B. Gradual weakening and cracking of the material.

How is a Brinell hardness test carried out?

A) A hardened steel or carbide ball is pressed into the material's surface under a specific load, and the diameter of the indentation is measured to calculate hardness.

Which of the following lists four methods for non-destructive crack detection?

A) Ultrasonic Testing, Magnetic Particle Testing, Dye Penetrant Testing, X-ray Inspection

With reference to fatigue failure of components, which of the following correctly describes the three stages of fatigue failure.

A) Crack Initiation, Crack Growth, Rapid Fracture Stage 1: Microcracks form at stress concentrators (e.g., surface defects or grain boundaries). Stage 2: The crack slowly propagates through the material under cyclic loading. Stage 3: The crack grows rapidly, leading to sudden failure of the component.

With reference to the installation of copper pipes in engine cooling systems, which of the following are three possible causes for their premature failure?

A) Corrosion, Overheating, Vibration Fatigue

With reference to the installation of copper pipes in engine cooling systems, which of the following are four recommendations for their installation?

A) Ensure Proper Support and Alignment, Use Correct Fittings, Avoid Sharp Bends, Apply Appropriate Insulation

What is a typical safety coefficient designed into a propeller shaft of a superyacht?

B) 2.0

How can false brinelling be reduced in practice?

A) By using vibration dampeners or isolators to minimize vibrations during storage or transportation.
1 / 17

AME Unit 10 Control systems, Block Diagrams

Explain the term "failsafe" in a control system and provide TWO examples of its application.

 

C) A failsafe is a feature that causes a system to enter a safe state in the event of a failure. Examples include spring-loaded valves and emergency shutdown systems.

Why might a split range control system be preferred over separate control systems for heating and cooling in marine engine applications?

 

B) It provides smoother transitions between heating and cooling.

Which of the following might be used as an actuator in a closed-loop engine cooling control system?

B. Coolant Pump or Valve

Which of the following best describes the role of the controller in a split range control system?

 

B) The controller outputs a signal that is divided between heating and cooling operations.

In a cascade control system for regulating the freshwater coolant temperature of a diesel engine, which of the following best describes the role of the secondary controller?

 

C) It adjusts the flow of coolant to maintain the desired temperature

What component in a hydraulic circuit is used to control the direction of fluid flow?

C) Directional control valve

2. In the control block diagram, which block provides feedback on the actual water level?

 

C. Sensor

In a closed-loop engine cooling system, which component is responsible for comparing the actual temperature to the desired set point?

C. Controller

What is the purpose of the "Coolant Flow Control" block in a closed-loop engine cooling system?

B. To adjust the coolant flow based on the controller's output

What is a common issue that can arise in a split range control system when the control valves are not properly calibrated?

B) Both control valves may remain partially open, leading to inefficient cooling.

Which of the following is a common cause of hydraulic fluid contamination?

B) Poorly maintained seals and filters

What is the typical effect of a malfunctioning temperature sensor in a closed-loop engine cooling control system?

B. Inaccurate temperature measurements, leading to potential overheating or overcooling

How is the speed of an actuator controlled in a hydraulic circuit?

C) By regulating the flow rate with a flow control valve

In a split range control system, what typically happens when the controller's output is in the lower range?

 

C) The heating valve is opened, and the cooling valve remains closed.

What is the role of the "Process Element" block in the water level control system?

D. To represent the tank or reservoir holding the water

What could happen if the split range control system's sensors fail to provide accurate temperature readings?

B) The system may overheat the engine due to a lack of proper cooling.

Why is it important for the closed-loop engine cooling system to be automatic?

B. To maintain optimal engine temperature without constant human intervention

Which of the following actions should be taken first when the jacket water temperature continues to rise despite all systems appearing to be in good condition?

 

C. Inspect the heat exchanger for blockages

In a manually operated water level control system, which block directly affects the flow of water into or out of the tank?

D. Manual Controller

1. What does a block in a control block diagram typically represent?

 

B) An individual component or function in the control system

Why is the cascade control method preferred over single-loop control for regulating the freshwater coolant temperature of a diesel engine?

 

B) It minimizes temperature fluctuations more effectively

In a split range control system, what occurs when the controller's output signal reaches the upper range?

 

A) The heating valve closes, and the cooling valve begins to open.

What happens if the "Controller" in a closed-loop engine cooling system receives a signal indicating that the temperature is too high?

B. It will increase the coolant flow

Why might a "Comparator" block be included in a control block diagram, even if it's not explicitly shown in a purely manual system?

B. To compare the actual water level with the set point

What is the primary advantage of using a cascade control method in regulating the freshwater coolant temperature of a diesel engine?

 

B) It provides a faster response to disturbances

In a hydraulic system, what does a pressure relief valve do?

C) It protects the system from excessive pressure.

In a basic hydraulic circuit, what is the primary purpose of a hydraulic pump?

A) To convert mechanical energy into hydraulic energy

In the cascade control method, what is the consequence of a poorly tuned secondary controller?

 

B) The coolant temperature may oscillate

How does a controller block typically function in a control block diagram?

B) It compares the actual output with the desired set point and makes adjustments

How does the feedback loop function in a closed-loop engine cooling control system?

B. It provides temperature measurement to the controller for adjustment

1. What does the "Manual Controller" block represent in a water level control system?

 

C. The valve or dial used to adjust the water flow

What is a potential action to take if an airlock is suspected in the cooling system?

 

B. Bleed the cooling system

7. What role do sensors play in a control block diagram?

 

B) They measure the system’s output and provide input to the controller

2. In a control block diagram, what is the purpose of the arrows or lines?

 

B) To show the connection between components

What is the principle of a cascade control method used for regulating the freshwater coolant temperature of a diesel engine?

 

B. The method employs two control loops where the primary loop regulates the coolant temperature, and the secondary loop controls a related variable, such as coolant flow, to improve stability and response.

Explain the term "failset" in a control system and provide TWO examples of its application.

C) A failset is a predetermined state that a system moves to when it fails to operate correctly. Examples include valves that default to open or close positions and motor-driven actuators that move to a safe position.

How does a split range control system respond when the jacket water temperature rises above the setpoint?

 

C) It opens the cooling valve while closing the heating valve.

What is meant by a 4:3 control valve?

 

A) A control valve with four ports and three positions, used to regulate fluid flow in hydraulic systems.

What could be a possible cause of the high jacket water temperature alarm, despite the header tank being full and both HT and SW pumps running in good condition?

 

A. Blocked heat exchanger

In a hydraulic circuit, what role does the reservoir play?

C) It stores hydraulic fluid.

What is the purpose of having a deadband or overlap in the control signal range in a split range control system?

 

C) To provide a buffer zone where neither valve operates, allowing temperature stabilization.

If the heat exchanger is found to be clear, what could be another potential cause of the rising jacket water temperature?

A. Airlock in the cooling system

What is the primary function of an automatic closed-loop engine cooling control system?

B. To maintain the engine temperature within a desired range by automatically adjusting the coolant flow

How can incorrect tuning of the PID controller in a split range control system affect the jacket water temperature control?

B) The system may experience excessive oscillation, leading to temperature instability.

In a closed-loop engine cooling control system, what role does the "Temperature Sensor" play?

B. It provides a measurement of the engine temperature to the controller

How could an improper range setting in a split range control system affect the engine cooling process?

B) The system may struggle to transition smoothly between heating and cooling modes.

What is the function of a hydraulic cylinder in a simple hydraulic circuit?

B) To convert hydraulic energy into mechanical energy

What is the purpose of the "Set Point" block in the control block diagram?

C. To provide the desired water level that the operator aims to maintain

What type of valve actuator is commonly used in a split range control system for the jacket water temperature of a main engine?

 

B) Pneumatic actuators

Which of the following is a typical setpoint for the secondary controller in a cascade control system regulating the freshwater coolant temperature?

Answer: D) Outlet coolant temperature

What is a potential issue with the mechanical components of the control valves in a split range system?

B) The valves may become stuck or slow to respond, causing poor temperature control.

Which of the following best describes a block diagram of a split range control system used to control the jacket water temperature of a main engine?

 

A) A single controller adjusts both heating and cooling valves, with the signal split into two ranges: one range controlling the heating valve and the other range controlling the cooling valve.

Which of the following conditions would likely lead the split range control system to close the heating valve completely?

 

C) When the jacket water temperature is above the setpoint.

How does the feedback path function in a manually operated water level control system?

C. It provides the actual water level measurement back to the manual controller

What is the function of a feedback loop in a control block diagram?

C) To compare the output with the set point and adjust the system accordingly

What is the primary advantage of using a split range control system to manage the jacket water temperature in a main engine?

 

B) It simplifies the control system by using a single controller to manage both heating and cooling.

What does the "Controller" block in an automatic closed-loop engine cooling system do?

C. Compares the actual engine temperature to the desired set point and adjusts the coolant flow accordingly

In a control block diagram, what does a gain block represent?

B) The amount of signal amplification or attenuation

What does the term "set point" refer to in a control block diagram?

B) The desired value that the system aims to achieve

What do summing points in a control block diagram do?

A) Combine or subtract signals to form a new signal
1 / 60

AME Unit 11 PID, Engine Governors, Control Terms

What happens when the flow out is increased in a system where the water tank level is controlled by a float and lever proportional system?

 

B) The float drops, causing the control valve to close, reducing the inflow.

Describe the reasons for integrating the error signal and the effect it has on the governor fuel rack.

 

A) Integrating the error signal helps in eliminating steady-state error by providing continuous correction over time, leading to a gradual adjustment of the governor fuel rack to maintain the desired engine speed.

Explain repeatability in control terms.

 

A) Repeatability refers to the ability of a control system to return to the exact same output every time a specific input is applied, assuming no changes in system conditions. Reason: This accurately describes repeatability as the system's ability to consistently produce the same output for the same input under unchanged conditions.

With reference to engine governors, explain stability.

 

A) Stability refers to the governor's ability to maintain a constant engine speed without oscillations or fluctuations when subjected to varying loads. Reason: Stability in governors is about how consistently the engine speed is maintained despite changes in load or other disturbances.

Explain the purpose of Derivative Action.

 

B) Derivative Action helps to anticipate future errors by reacting to the rate of change of the error, thereby improving the system’s stability and response time.

State the reasons for fitting a pneumatic process valve with a volume booster.

 

A) A volume booster is fitted to increase the flow rate of air to the actuator, enabling faster valve movement and reducing the time required to achieve the desired valve position.

With reference to hydraulic governors fitted to alternators designed to run in parallel, explain why these governors have adjustable integral action.

 

B) To ensure that the governor can handle variations in load and maintain stable operation by adjusting the steady-state accuracy.

What is a potential drawback of using an On-Off control system?

 

B) It is unable to achieve precise control, leading to oscillations around the set point.

What is the primary characteristic of a Discontinuous (On-Off) control system?

B) The output is either fully on or fully off, with no intermediate states.

Describe the effect of increasing the controller gain with respect to the steady-state tank level when the outflow is increased in a float and lever proportional system.

 

B) The steady-state tank level will oscillate more and be less stable.

Describe using control block diagram terms how a governor maintains the speed of a diesel engine driving a generator.

 

B) The governor compares the actual engine speed to the desired speed setpoint and uses a proportional-integral-derivative (PID) control block to adjust the fuel input and maintain the engine speed.

With reference to engine governors, explain hunting.

 

A) Hunting is the term used to describe a governor's inability to maintain a constant engine speed due to excessive fluctuation in engine speed around a set point. Reason: Hunting occurs when the governor repeatedly overshoots and undershoots the target speed, causing erratic engine performance.

How is the level in a water tank controlled by a float and lever proportional system?

 

A) The float rises with the water level, causing the lever to close a valve, stopping the inflow of water when the desired level is reached.

How can the gain of a control system be increased or decreased?

 

A) Increase the gain by reducing the proportional band; decrease the gain by increasing the proportional band.

Explain derivative action in control terms.

 

A) Derivative action involves adjusting the control output based on the rate of change of the error, aiming to predict future errors and reduce overshoot.

State with reasons, the type of actuator fitted to the process valves for a fuel supply system in which the valve must not move on loss of power to the control system.

 

A) Electric Actuator with Fail-Safe Mechanism: Reason: This actuator includes a fail-safe mechanism that ensures the valve remains in its last position or moves to a predetermined safe position if there is a loss of power.

Explain dead zone in control terms.

 

A) Dead zone refers to a range within which changes in input do not produce any change in the output of a control system. Reason: This correctly describes dead zone as a region where the system is unresponsive to inputs within that range.

Define the term Proportional Action.

 

A) Proportional action adjusts the control output based on the magnitude of the error, where the output is directly proportional to the difference between the setpoint and the actual value.

With reference to engine governors, explain sensitivity.

 

B) Sensitivity refers to the governor’s response to small changes in the fuel supply, affecting the engine speed control. Reason: A sensitive governor will react quickly to minor adjustments in fuel input, thereby maintaining precise engine speed control.

How does hysteresis improve the performance of an On-Off control system?

B) It prevents rapid cycling by creating a dead zone between switching on and off.

With reference to hydraulic governors fitted to alternators designed to run in parallel, explain how two generators operating in parallel are able to achieve a stable load share with a 50/50 ratio.

 

C) By synchronizing the generators' speed and voltage settings, and using governors with equal proportional and integral action to balance the load distribution.

Explain the purpose of Integral Action.

 

B) Integral action integrates the error over time to eliminate steady-state error, ensuring that the system eventually reaches the setpoint.

Explain proportional bandwidth in control terms.

 

C) Proportional bandwidth is the width of the proportional band within which the control action is active and varies linearly with the error.

With reference to engine governors, explain isochronous governing.

 

A) Isochronous governing ensures that the engine speed remains constant regardless of the load applied, maintaining the same speed even with varying demands. Reason: Isochronous governing is designed to keep the engine speed constant, independent of changes in load.

With reference to engine governors, explain speed droop.

 

A) Speed droop is the reduction in engine speed that occurs when the engine is subjected to an increase in load, relative to the no-load speed. Reason: Speed droop measures how much the engine speed decreases from its no-load speed when a load is applied.

Describe a possible effect of excessive Integral Action.

 

B) Excessive Integral Action can cause the system to oscillate or exhibit sustained oscillations around the setpoint due to an overcompensation of errors.

State the reasons for fitting a pneumatic process valve with a feedback positioner.

 

A) A feedback positioner is fitted to monitor the valve position and provide real-time correction signals to ensure the valve remains at the desired position, improving accuracy and stability in the process control.

2. Which of the following is a typical application of an On-Off control system?

 

B) Temperature control in a household thermostat.

What is the relationship between proportional band and gain in a control system?

 

B) Proportional band is inversely proportional to gain.

Explain hysteresis in control terms.

 

A) Hysteresis is the phenomenon where the output of a control system depends on its past input, causing a lag or delay in response. Reason: This describes hysteresis correctly, where the system’s output is influenced by the history of inputs, leading to different responses for increasing versus decreasing inputs.

Explain proportional bandwidth in control terms.

 

A) Proportional bandwidth refers to the range of input values over which the proportional control action is effective in adjusting the output of a system. Reason: This describes how the range within which proportional control can operate effectively is defined, focusing on the input values that impact the output.

State with reasons, the type of actuator fitted to the process valves for a lubrication oil cooling system in which the valve diverts the oil through a cooler.

 

B) Pneumatic Actuator: Reason: Pneumatic actuators provide reliable and fast operation and are well-suited for applications requiring frequent adjustments to the valve position, such as diverting oil flow through a cooler.

Describe the effect of excessive Derivative Action.

 

B) Excessive Derivative Action can cause the system to become overly sensitive to noise, leading to oscillations and instability.

Explain settling time in control terms.

 

B) Settling time is the time required for the system's output to remain within a specified range around the set point after a disturbance, and it measures the time until the output stops oscillating significantly. Reason: This correctly describes settling time as the time it takes for the output to stay within a certain percentage of the set point and cease significant oscillations.

In an On-Off control system, what happens when the controlled variable exceeds the set point?

B) The system switches off the output to bring the variable back to the set point.

Explain integral action in control terms.

 

A) Integral action refers to the ability of a control system to eliminate steady-state error by continuously adjusting the control output based on the accumulated error over time.

Describe integral action in a control system.

 

B) Integral action increases the control output to eliminate steady-state error over time by integrating the error signal.
1 / 37
0 0 votes
Article Rating
Subscribe
Notify of
guest
1 Comment
Most Voted
Newest Oldest
John
John
2 months ago

Great,just what I needed

0
Reply
1
0
Would love your thoughts, please comment.x
()
x