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OCHS 2340 > 9. Boiler Pressure Vessel Safety > Flashcards

9. Boiler Pressure Vessel Safety Flashcards

1
Q

What is a pressure vessel?

A

A relatively high-pressure component, with a greater cross-section than the associated pipe/tubing capable of storing, distributing, or handling a gas/vapour/liquid under pressure.

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2
Q

In a pressure vessel, what is considered low/intermediate/high pressure?

A

Low pressure = gas <150psi or liquid <1500psi

Intermediate pressure = gas between 150 and 3000psi or liquid between 1500 and 5000psi

High pressure = gas >3000psi or liquid >5000psi

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3
Q

What are the four main types of boiler found in the workplace?

A
  • Fire-tube boilers
  • Water-tube boilers
  • Tubeless boilers
  • Electric boilers
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4
Q

What are fired and un-fired pressure vessels?

A

Fired pressure vessels are essentially boilers, and include combustion.

Un-fired pressure vessels, are pressure vessels that are not connected to any flames. These can be positive or negative pressure vessels.

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5
Q

What are the three basic elements/components of a basic boiler?

A

The vessel or shell itself

A series of tubes that pass through the vessel

A heat source (burner or electrical element)

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6
Q

What is a fire-tube boiler?

A

The vessel contains water.
A fuel burner produces hot gasses that are passed through tubes in the vessel.

Typically smaller, operating at pressures up to 150psi.

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7
Q

What is a watertube boiler?

A

Water filled tubes run through the vessel.
The burner fills the vessel with hot gases.

Watertube boilers can be very big, and operate at pressures greater than 3,500psi

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8
Q

What are electric boilers?

A

Electric boilers use electrical elements to heat water.

They can be extremely small and highly-efficient.
Electric boilers are common in HVAC systems.

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9
Q

What are the two types of unfired pressure vessel?

A

Thick-walled.
Thin-walled.
Neither is typically portable.

*Portable pressure vessels (compressed gas cylinders) are the arguable third type, because they are portable.

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10
Q

What is a thin-walled pressure vessel?

A

An unfired pressure vessel, which may be positive or negative pressure.

The vessel diameter is 10 times (or greater) than the wall thickness.

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11
Q

What is a thick-walled pressure vessel?

A

An unfired pressure vessel, which may be positive or negative pressure.

The vessel diameter less than 10 times than the wall thickness.

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12
Q

Compare/contrast pressure vessels and boilers.

A

Pressure vessels hold liquids, gases or both under pressure.

Boilers hold a liquid, that is heated. Boilers often have to withstand high pressure, in which case the boiler would be considered a pressure vessel.

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13
Q

List 4 examples and purposes of pressure vessels in the workplace.

A
  • Storage of compressed air for pneumatic tool operation.
  • Storage of pressurized liquids for dispensing into a production process.
  • Storage of compressed gasses for use in medicine.
  • Vacuum trucks used for cleaning drains and pipes.
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14
Q

List 4 examples and purposes of boilers in the workplace.

A
  • Industrial kitchens
  • Building heating systems
  • Pulp/paper manufacturing
  • Autoclaves for medical sterilization
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15
Q

What is a tubeless boiler?

A

A vessel containing water is heated from an external flame.

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16
Q

What direct OHS hazards are associated with failure of a pressure vessel?

A
  • Sudden release of pressure
  • Sudden release of materials under pressure
  • Flying pieces of the vessel and associated components
17
Q

What indirect OHS hazards are associated with failure of a pressure vessel?

A
  • Release if materials that are harmful to the environment
  • Worker exposure to combustion exhaust gasses
  • Confined space hazards associated with workers entering pressure vessels
18
Q

What are the four basic known causes of pressure vessel accidents?

A
  • Failures from corrosion
  • Material failures from stress
  • Incorrect burner firing and shutdown
  • Failure of safety devices
19
Q

Who regulated pressure vessel safety?

A

In BC: Technical Safety BC.

Usually a quasi-government agency that is not the OHS regulator.

20
Q

What is ASME?

A

American Society of Mechanical Engineers

21
Q

Name two key mandatory design standards for pressure vessels.

A

ASME boiler and pressure vessel code 2019

CSA B51

22
Q

List a control to prevent each of the four basic known causes of pressure vessel accidents?

A

Corrosion:
correct material, anticorrosion chemicals

Stress Failure:
correct design, manufacture, installation, operation and repair

Incorrect Burner Firing or Shutdown:
operator training, correct design

Failure of Safety Devices:
correct design and operation, inspection and maintenance

23
Q

What is the three-pronged approach to reduce the risk of hazards associated with pressure vessels?

A

Safety by design & design standards

Mandatory standards (installation, inspection, maintenance and repair)

Mandatory education and training for operators

24
Q

What key safety information is covered in the ASME boiler and pressure vessel code 2019, and CSA B51?

A

Requirements for explanatory nameplate

Safety device requirements

structural strength requirements

qualifications of those who manufacture, install or repair

Required registration of pressure vessels with regulators

Inspection requirements

25
Q

What regulation primarily covers pressure vessels in BC?

A

The Power Engineers, Boiler, Pressure Vessel and Refrigeration Safety Regulation.
(PBPR Regulation)

26
Q

Who enforces the PBPR regulation?

A

The Power Engineers, Boiler, Pressure Vessel and Refrigeration Safety Regulation is enforced by Technical Safety BC.

27
Q

What is a chief engineer, context pressure vessels?

A

A power engineer, designate by the owner, to be responsible for operation and maintenance of a plant.
Responsible for ensuring regulated work is performed by qualified persons.

28
Q

What is a shift engineer, context pressure vessels?

A

A power engineer, under a chief engineer, who is in charge of a plant when the chief engineer is not present.

29
Q

What are the safety duties of power engineers operating boilers?

A

To inspect every boiler, pressure vessel, and associated parts as soon as practicable after starting shift.

30
Q

How are plants classified (context pressure vessels)?

A

Plants are classified by the type and capacity of the boilers.

31
Q

List four legal operations of boiler owners.

A

Owners must hold and post a valid operating permit.

Owners must designate a chief engineer, and shift engineers for then the chief is away from the plant.

Owners are responsible for the safety of all employees.

Owners must apply for a new permit if there are changes that may re-classify a plant.

32
Q

What are the three main categories of safety devices in pressure vessels?

A

Gauges, alarms, etc.
(alert operators to problems)

Automatic intervention devices
(Monitors that automatically intervene in an emergency)

Pressure relief devices
(mechanical pressure relief devices)

33
Q

What are the three basic types of pressure relief devices (context pressure vessels)

A

Reclosing
(open when pressure high, closes once pressure reduced)

Non-reclosing
(opens when pressure high, but must be replaced or manually closed )

Vacuum
(opens when interior is under-pressure and re-closes once pressure increases.

34
Q

List three types of reclosing pressure relief valves.

A

Safety Valves
Gas & vapour valve that opens at a set pressure, and closes at a lower pressure. Part of normal operation and safety release.

Relief Valves
Liquids valve that open and close at a set pressure. Regularly open/close during operations. Not true safety device.

Safety Relief Valves
Liquid, gas, and vapour valves that pen and close rapidly for safety relief.

35
Q

List three types of non-reclosing pressure relief devices.

A

Rupture discs

Pin devices
(Pins hold a plug in place and break or buckle under excess pressure)

Fusible plugs
(melt under heat to allow venting)

36
Q

What are pressure vacuum relief devices (context pressure vessels)

A

When the pressure inside the vessel is excessively low relative to the external pressure, the device opens to equalize pressures within acceptable levels.

37
Q

Briefly summarize the role of the ASME Boiler Code and CSA B51 in pressure vessel safety programs.

A

The ASME Code and CSA B51 most importantly provide mandatory requirements for:

  • pressure vessel design
  • manufacture, installation, inspection, maintenance, and repair of pressure vessels and their associated component

OCHS 2340 (12 decks)

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