AME 1 End of Unit

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

This is the correct answer as it accurately lists the three materials commonly used for ship's side valves and provides a concise explanation of their suitability.

Why the other options are incorrect:

• A. Cast iron: While cast iron can be used in some marine applications, it's generally not suitable for ship's side valves due to its brittleness and susceptibility to corrosion in the harsh marine environment.
• C. Aluminum and copper: While both aluminum and copper have their applications in marine engineering, they are not typically used for ship's side valves. Aluminum may lack the necessary strength and corrosion resistance, while copper is often alloyed with other metals (like tin to form bronze) to improve its properties for marine use.
• D. Plastic and rubber: These materials are not suitable for ship's side valves due to their lack of strength and durability to withstand the pressures and harsh conditions of the marine environment. They are also susceptible to degradation from exposure to saltwater and UV radiation.

Answer:

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

Explanation:

Solder is primarily an alloy of tin and lead, with the most common composition being 63% tin and 37% lead. This composition is known as eutectic solder and has a low melting point, making it ideal for joining metals. A common application on board a marine vessel would be for electrical connections.

Why the other answers are incorrect:

• A. 60% copper, 40% zinc; used for pipe joints: This composition describes brass, which is used for pipe joints, but it's not solder. Solder is a metal alloy used for joining metals together, typically with a lower melting point than the metals being joined.

   

  1. Solder - Wikipedia

  

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• B. 90% lead, 10% tin; used for electrical connections: While this is a type of solder, it contains a high percentage of lead, which is harmful and has been phased out in many applications due to environmental concerns. Modern solders primarily use tin and lead, or lead-free alternatives.
• D. 80% copper, 20% aluminum; used for propeller blades: This composition describes an aluminum bronze alloy, which is not solder. Solder is a low-melting point alloy specifically designed for joining metals.

Answer:

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

Explanation:

Cupro-nickel alloys typically contain around 90% copper and 10% nickel. They are widely used for heat exchanger tubes in marine applications due to their excellent resistance to saltwater corrosion.

Why the other options are incorrect:

• A. 70% copper, 30% nickel; used for engine blocks: While copper alloys are used in some engine components, this specific composition is not typically used for engine blocks. The properties required for engine blocks, such as heat resistance and strength, are better suited to other alloys.
• C. 60% copper, 40% zinc; used for propeller shafts: This composition describes brass, not cupro-nickel. Brass is often used for marine applications, but propeller shafts typically require higher strength and corrosion resistance than brass can provide.
• D. 80% copper, 20% tin; used for electrical wiring: This composition describes bronze, not cupro-nickel. While bronze has good conductivity, it's not the primary choice for electrical wiring due to its cost compared to copper. Additionally, copper is a more efficient conductor.

Answer:

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

Explanation:

Aluminium bronze typically consists of around 90% copper and 10% aluminum. It's widely used for marine applications, especially propeller blades, due to its excellent combination of strength, corrosion resistance, and resistance to cavitation.

Why the other options are incorrect:

• B. 70% copper, 30% zinc; used for electrical wiring: This composition describes brass, not aluminium bronze. While brass is used for some electrical applications, it's not the primary choice for marine environments due to its lower corrosion resistance compared to aluminium bronze.
• C. 60% copper, 40% tin; used for engine bearings: This composition describes bronze, not aluminium bronze. Bronze is used for bearings due to its good anti-friction properties, but aluminium bronze offers superior strength and corrosion resistance for marine applications.
• D. 80% copper, 20% lead; used for plumbing pipes: This composition describes lead brass, which is not commonly used in modern applications due to health concerns related to lead exposure. Aluminium bronze offers better corrosion resistance and mechanical properties for marine environments.

Answer:

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

1. Carbon Steel vs Stainless Steel - Markforged

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Explanation:

Stainless steel is the most suitable material for a centrifugal pump impeller in marine applications. It offers a combination of high strength to withstand the hydraulic forces exerted on the impeller, and excellent corrosion resistance to combat the aggressive marine environment.

While other materials like bronze and cast iron offer some advantages, they may not provide the necessary combination of strength and corrosion resistance for long-term reliable operation in marine conditions. Aluminum alloys, although lightweight, might not have sufficient strength for demanding pump applications.

Why the other answers are incorrect:

• A. Cast iron: While cast iron is strong and cost-effective, it is susceptible to corrosion in the marine environment, which can lead to pump failure.
• B. Bronze: Bronze offers good corrosion resistance, but it might not have the necessary strength for high-pressure pump applications. Additionally, bronze is generally heavier than stainless steel, which can impact pump efficiency.
• D. Aluminum alloy: Aluminum alloys are lightweight and corrosion-resistant, but they may lack the required strength and durability for centrifugal pump impellers, especially in high-pressure applications.

Stainless steel provides the optimal combination of strength and corrosion resistance, making it the preferred choice for centrifugal pump impellers in marine environments.

Answer:

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

1. What Is Admiralty Brass Properties Uses And Composition - Munot Metalloys

www.munotmetalloys.com

Explanation:

Admiralty brass is typically composed of approximately 70% copper, 29% zinc, and 1% tin. The addition of tin significantly improves the alloy's corrosion resistance, making it ideal for marine applications, especially heat exchanger tubes.

Why the other options are incorrect:

• A. 90% copper, 10% aluminum; used for propeller blades: This composition describes aluminium bronze, not admiralty brass. While both are used in marine applications, their specific properties and applications differ.
• C. 60% copper, 40% zinc; used for engine bearings: This composition describes brass, but not admiralty brass. While brass is used in various marine components, its properties are not ideal for heat exchanger tubes, which require better corrosion resistance.
• D. 80% copper, 20% lead; used for plumbing pipes: This composition describes lead brass, which is not commonly used due to health concerns related to lead exposure. Additionally, lead brass is not suitable for marine environments due to its susceptibility to corrosion.

Admiralty brass, with the addition of tin, offers superior corrosion resistance compared to standard brass, making it a suitable choice for heat exchanger tubes in marine applications.

Why D is the correct answer:

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

This is the correct answer because it directly addresses the primary reason why grey cast iron is unsuitable for ship's side valves: its brittleness. The marine environment is harsh, with potential for impacts, pressure fluctuations, and corrosion, which can easily lead to fractures in grey cast iron.

Why the other options are incorrect:

• A. Grey cast iron is highly resistant to corrosion in marine environments. This is incorrect. While cast iron can exhibit some corrosion resistance in certain conditions, the marine atmosphere, with its high salt content and humidity, is particularly aggressive, leading to rapid deterioration of grey cast iron.
• B. Grey cast iron possesses exceptional strength and ductility for withstanding marine conditions. This is incorrect. Grey cast iron is actually known for its low tensile strength and poor ductility, making it unsuitable for applications that require resistance to stress and strain, such as ship's side valves.
• C. Grey cast iron is lightweight, making it ideal for shipboard applications. While weight is a consideration in ship design, it's not the primary factor in choosing valve materials. Other materials like bronze or stainless steel offer better performance in marine environments while also being relatively lightweight.

Answer:

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

Explanation:

Austenitic stainless steel is primarily composed of iron, with chromium being the key alloying element providing corrosion resistance. Nickel is added to stabilize the austenitic structure and improve properties like ductility and toughness. While the exact percentages can vary depending on the specific grade, the general composition falls within the ranges provided in option A.

Why the other options are incorrect:

• B. Copper (50%), Zinc (30%), Tin (20%): This composition describes brass, not stainless steel.
• C. Aluminum (70%), Magnesium (20%), Silicon (10%): This composition is closer to an aluminum alloy, not stainless steel.
• D. Titanium (60%), Vanadium (25%), Molybdenum (15%): This composition describes a titanium alloy, not stainless steel.

Stainless steel is primarily an iron-based alloy with chromium as the essential element for corrosion resistance. Nickel is often added for improved properties.

Answer:

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

Explanation:

• A is correct. These elements are commonly added to steel to modify its properties, such as strength, hardness, corrosion resistance, and ductility.
• B is incorrect. While some of these elements might be used in specific steel alloys or as impurities, they are not primary alloying elements.
• C and D are incorrect. These elements are gases or alkali metals, respectively, and are not typically used as alloying elements in steel production.

Answer:

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

Explanation:

Cast iron is the most common material for cylinder heads in small auxiliary engines due to its excellent heat dissipation properties and high strength to withstand combustion pressures. It also offers good wear resistance.  

1. Abrasion resistant Cast iron

www.emcasting.com

While aluminum alloys and copper alloys have some advantages, cast iron is generally preferred for its overall performance and cost-effectiveness in this application.

Why the other answers are incorrect:

• B. Aluminum alloy: While aluminum alloys are lightweight and have good heat dissipation, they lack the necessary strength and heat resistance for a cylinder head, which is subjected to high pressures and temperatures during combustion.
• C. Copper alloy: While copper has excellent thermal conductivity, it is generally too soft for a cylinder head and lacks the necessary strength to withstand combustion forces.
• D. Stainless steel: Stainless steel is strong and corrosion-resistant, but it lacks the heat dissipation properties required for a cylinder head. It would overheat under the high temperatures generated during combustion.

Cast iron, with its combination of strength, heat resistance, and cost-effectiveness, remains the preferred choice for cylinder heads in small auxiliary engines.