Pipe Systems and Failures

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Questions and Answers

What type of corrosion mainly affects pipes carrying seawater?

Pitting corrosion

Galvanic corrosion (correct)

Uniform corrosion

Crevice corrosion

Which fitting is specifically used to change the direction of a pipe?

Tees

Flange

Elbow (correct)

Reducer

What is the primary purpose of valves in a piping system?

Change the diameter of the pipe

Support the weight of the pipe

Join two pipes together

Control the flow of fluids (correct)

What could cause pipe failure due to temperature effects?

Water hammer Signup and view all the answers

Which connection method uses gaskets to create a seal when bolting pipes together?

Flange connection Signup and view all the answers

What is the recommended spacing for pipe saddles to help maintain pipe alignment during thermal expansion?

6 meters Signup and view all the answers

What material should rollers for steel pipework be made from?

Ferrous material Signup and view all the answers

Which of the following is a major consideration in ensuring the flexibility of a pipework system?

Accommodating thermal expansions Signup and view all the answers

What is the primary purpose of expansion fittings in pipe systems?

To accommodate changes in length due to temperature fluctuations Signup and view all the answers

How do stainless steel bellows expansion joints benefit pipe systems?

They absorb movement or vibration in several planes Signup and view all the answers

What is a potential weak point in a piping system?

Flanges used to connect pipes to pumps Signup and view all the answers

What is the role of watertight bulkheads in a piping system?

They allow pipes to pass through without impairing integrity Signup and view all the answers

Which of the following factors must be considered when choosing a bellows expansion joint?

Maximum and minimum working temperatures Signup and view all the answers

What can happen if there is insufficient support for pipes?

Pipes can fracture due to movement Signup and view all the answers

Which type of mechanical joint provides axial resistance and is suitable for medium to high-pressure pipes?

Grip type mechanical joints Signup and view all the answers

What is an important characteristic of expansion bellows compared to other fittings?

They can accommodate movement without impacting total line length Signup and view all the answers

Which type of mechanical joint can only be used under low or medium pressure?

Slip type Mechanical joints Signup and view all the answers

What is a characteristic feature of Swage type Mechanical joints?

They are pre-assembled and non-dismantleable. Signup and view all the answers

Which type of mechanical joint is suitable for high-pressure pipes?

Flared type Mechanical joints Signup and view all the answers

In pipe fittings, which type of tee connector is referred to as the Y type Tee?

Y type Tee Signup and view all the answers

Which equation correctly calculates the internal diameter of the bilge main in a tanker?

d = 35 + 3√Lo(B+D) Signup and view all the answers

Which of these pipe fittings can be classified as a reducer?

Eccentric Reducer Signup and view all the answers

What type of clamp is designed to withstand high pressure?

High Pressure Clamp Signup and view all the answers

In piping systems, what is the primary purpose of the bilge system?

To remove small quantities of fluid that have leaked or condensed Signup and view all the answers

What is the primary purpose of the ballast system in a ship?

To increase draught, particularly stern draught, when sailing without cargo Signup and view all the answers

Which material is primarily used for fire mains system piping?

Mild steel Signup and view all the answers

How does the sprinkler system detect and extinguish a fire?

By automatically releasing at temperatures of about 70°C Signup and view all the answers

What is the typical working pressure for the fire main system?

10 bar Signup and view all the answers

What distinguishes inert gas piping in terms of diameter and pressure?

It is typically low-pressure with larger diameter piping Signup and view all the answers

What is the purpose of flushing the sprinkler system with freshwater after use?

To minimize corrosion Signup and view all the answers

What is the design pressure for the main CO2 lines in the CO2 system?

160 bar Signup and view all the answers

What is the expansion ratio of the foam used in the foam system piping?

900 to 1 Signup and view all the answers

What is the primary function of double skins in pipes?

To guard against fuel spraying caused by pipe fracture. Signup and view all the answers

What method is commonly employed to prevent oil spraying from a flange?

Taping the flange. Signup and view all the answers

How do cocks control the flow in a pipe system?

By rotating the plug. Signup and view all the answers

What characteristic of cocks is preferable in machinery spaces for fuel or lubricating oil tanks?

Parallel plugs. Signup and view all the answers

What is a key role of valves in a water-supply system?

To stop, throttle, or control the flow of water. Signup and view all the answers

Which component is NOT mentioned as a type of cock or valve?

Plastic Ball Valve. Signup and view all the answers

What should always be avoided regarding the routing of fuel or lubricating oil pipes?

Allowing pipes to lie above a hot surface. Signup and view all the answers

What is a critical feature valves must have for proper operation?

Accurate control of fluid flow and pressure. Signup and view all the answers

Study Notes

Pipe Failure Causes

Water hammer, low temperature, expansion, and pipe alignment are all causes of pipe failure.

Pipe Corrosion and Erosion

Most ship pipes are made of ferrous material, which is susceptible to all forms of corrosion.
Galvanic corrosion is a major challenge for sea water carrying pipes.
Galvanic corrosion can occur when differing metals are electrically connected and in direct contact with sea water.
Rust is a common corrosion problem for steel pipes exposed to sea water.

Pipe Connections

Pipe connections are done through welding, female, flange, male, and other methods.

Pipe Fittings

Elbows are used to change pipe direction and are available in various angles and materials.
Tees are used to create branch lines off the main pipe.
Reducers allow for smooth transitions between different pipe diameters.
Flanges connect pipes to other equipment using bolts and gaskets.
Valves control fluid flow and come in various types like gate valves, ball valves, and check valves.

Pipework Flexibility

Pipework must be flexible to accommodate expansion and contraction caused by temperature changes.
Metallic pipes expand and contract with temperature changes.
Spacers are used during installation to compensate for expansion.

Pipe Chair, Roller, and Saddle

Roller supports are ideal for supporting pipes and allowing for movement in two directions.
Rollers should be ferrous for steel pipes and non-ferrous for copper pipes.
A pipe saddle bolted to a support bracket every 6 meters helps keep pipe alignment during expansion and contraction.
It’s not recommended to support a bottom pipe from a top pipe using a pipe clip.

Expansion Fittings

Expansion fittings are used to accommodate changes in pipe length due to temperature changes, preventing stress and distortion.
Expansion fittings accommodate expansion without changing the overall length of the pipe.
Commonly called expansion bellows, they are designed with a bellows construction.
Expansion fittings can also be made from the pipework itself.

Sliding Joint

A sliding joint is a type of expansion joint with an anchored sleeve, stuffing box, and gland, allowing an extension of the joining pipe to slide freely within limits.

Steam-Line Expansion Arrangement

Allows for length changes using a right angle bend arrangement or a loop.

Stainless Steel Bellows Expansion Joints

Commonly used due to their ability to absorb movement and vibration in multiple planes, eliminating maintenance, reducing friction, and minimizing heat loss.
When choosing these joints, the maximum and minimum working temperatures must be considered, and they must be installed so they are neither overcompressed nor overextended.

Expansion Bellows

Requires no packing.

Watertight Bulkheads

Special fittings are used to maintain the integrity of watertight bulkheads when pipes pass through them to prevent any impairment.
The large flange of the fitting covers the necessary clearance in the bulkhead.

Connection to Pumps

Pumps are connected to pipes using flanges, which can be a weak point in the piping system.
Welded flanges are prone to corrosion in the weld metal or the heat-affected zone.
Regular examination of pipes in wet areas where corrosion is likely is crucial.

Pipe Support Spacing

Clips and supports are used to hold pipes in position, prevent movement, and minimize vibration.
Insufficient support can cause pipe fractures.
Clip loosening can lead to failures due to mechanical wear.
Mechanical Joints:
- Grip type: provides axial resistance for medium or high pressure pipes.
- Machined groove type: provides axial resistance for medium or high pressure pipes.
- Slip type: No axial resistance, can only be used with low or medium pressure pipes, the seal is achieved by packing.
- Swage type: Pre-assembled and cannot be dismantled, can be accommodated for medium to high pressure pipes.
- Press type: Pre-assembled and cannot be dismantled, can be used with low to medium pressure pipes, an internal seal achieves tightness.
- Byte type/compression: for high-pressure pipes.
- Flared type: for high-pressure pipes, commonly used for copper pipes in refrigeration systems.

Pipe Fittings Breakdown (Specific Types)

Elbows:
- 90 Welded Elbow
- 45 Long Type Welded Elbow
- 90 Welded Elbow - Straight End
- 45 Welded Elbow
- Threaded Elbow
Tees:
- Equal Welded Tee
- Y type Tee
- U type Tee
- Equal Union
- Cross Clamp
- Cross Welded Clamp
Reducers:
- Reduce Clamped Reducer
- Eccentric Reducer
- Sanitary Reducer
- Concentric Reducer
Clamps:
- Clamp
- High Pressure Clamp
- Three-piece clamp
- Heavy Duty clamp
Pipe Hangers:
- Pipe hanger
- Pipe clip
- Hexagon Pipe Support
Unions:
- Stainless steel blind nut/cap
- Sanitary Union, Ferrule
- Stainless Steel Union
- SMS union
- Sanitary Union
- Stainless Steel Male
- Stainless Steel Round Nut
- Stainless Steel Male

Bilge Piping System

Bilge systems remove small quantities of leaked or condensed fluids from dry spaces.
The diameter of the bilge main is calculated using the formula: d = 25+1.68√L(B+D), where:
- d = internal diameter of bilge main (mm)
- L = length between perpendiculars (m)
- B = extreme breadth (m)
- D = moulded depth (m)
In tankers with separate cargo pumping and piping systems, the enclosed space is the engine room and the bilge main diameter is calculated as follows: d = 35+3√Lo (B+D), where:
- Lo = length of the engine room (m)

Ballast System Piping

Ballast is used to increase the ship's draft, especially the stern draft, when sailing without cargo.
On tankers, the entire ballast system is located in the cargo area and operated from a pump room.
Ballast piping is typically made of ordinary mild steel.
The size of the ship determines the capacity of the ballast system.

Fire Mains System Piping

Fire mains are designed to deliver saltwater for manual firefighting using hydrants and hoses.
The fire main is designed for a working pressure of around 10 bar.
Fire main pipes are susceptible to corrosion both externally and internally.
Flanged connections are used to join the pipes.

Sprinkler System Piping

Small bore pipes are permanently charged with freshwater at around 10 bar pressure.
Sprinkler systems are designed to release automatically at temperatures around 70°C, detecting and extinguishing fires.
The system uses saltwater after the freshwater supply is depleted.
After use, it’s flushed with freshwater to minimize corrosion.

Inert Gas (IG) System Piping

Fitted on tankers over 20,000 dwt and tankers with crude oil washing (COW) systems.
IG piping is usually large diameter, low-pressure, mild steel with smaller diameter branch lines.
The internal surface of IG piping typically does not corrode.
The external surface is painted, but corrosion occurs if the paint coating deteriorates.

CO2 System Piping

Relatively small bore, hot galvanized mild steel piping designed to withstand high surge loads during CO2 release.
Main CO2 lines are designed to withstand the same pressure as CO2 bottles, while distribution lines off the main valve are designed for lower pressure.
The main line is typically pressure tested to 200 bar, with a design pressure of at least 160 bar.

Foam System Piping

Mild steel low-pressure piping using foam with an expansion ratio of 900 to 1.
Line pressure ranges from 4 to 5 bar.
Foam compound in storage tanks is pumped to a foam generator.
The system delivers foam at a rate of one meter of compartment depth per minute.
Double skins are necessary because pipe fracture can cause fuel to spray in a fine aerosol, which ignites when in contact with hot surfaces.
The second skin prevents direct fuel spraying.
The pipe design ensures fuel containment between the outer skin and the main pipe, draining into a collecting tank with a high-level alarm.

Low-Pressure Lubricating and Fuel Oil Pipes

Low-pressure lubricating and fuel oil pipes near hot surfaces must be secured to prevent oil spraying from a flange.
Flanges are typically taped for this purpose.
Routing pipes away from hot surfaces is another preventive measure.
Pipes should never be allowed to run above hot surfaces to prevent leaking oil from falling onto them.

Cocks and Valves

Cocks and valves control or interrupt flow.
Cocks rotate a plug to control or interrupt flow.
Valves lower, raise, or rotate a disc, or control movement of a ball to control or interrupt flow.
Cocks and valves have bodies with flanged or screwed ends for connecting to joining pipes.

Cocks Breakdown

Can be straight-through, right-angled, or open-bottomed depending on their placement in a pipe system.
The plug can be tapered or parallel, with tightness achieved by lapping in or resilient packing material.
Short sounding pipes for fuel or lubricating oil tanks in machinery spaces must have cocks with parallel plugs instead of tapered ones.

Valves

Used to stop, throttle, and control water flow in pipelines.
Used to control flow, pressure, and direction of fluid flow.
Valves must be accurate in controlling fluid flow, pressure, and the sequence of operation.

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Description

Explore the various causes of pipe failure, including water hammer and low temperature effects. Learn about different types of pipe corrosion, especially in marine environments, and the importance of proper pipe connections and fittings. This quiz covers essential knowledge for anyone involved in pipe system maintenance and design.