Confined Space Training Certificate Risk Assessment and Safe Systems 2 — Questions and Answers
Question 1: A confined space entry permit should specify a time limit because:
- Workers get bored after 30 minutes
- Conditions may change over time, PPE has limited duration, and it ensures periodic reassessment of safety (Correct answer)
- UK law mandates a maximum entry time of one hour
- It reduces the employer's liability in case of an accident
Correct answer: Conditions may change over time, PPE has limited duration, and it ensures periodic reassessment of safety
Time limits ensure that conditions are periodically reassessed, that PPE such as breathing apparatus is not used beyond its rated duration, that workers are not exposed for excessive periods, and that the permit is formally reviewed. Changed conditions may require a new permit with updated precautions.
Question 2: Isolation of services and pipework connected to a confined space is a critical part of the safe system of work. Effective isolation typically requires:
- Closing valves and placing a sign on them
- Physical disconnection, blanking, or the use of lock-out/tag-out procedures to prevent accidental introduction of substances or energy (Correct answer)
- Verbal instruction to the control room not to open any valves
- Turning off the main power switch for the building
Correct answer: Physical disconnection, blanking, or the use of lock-out/tag-out procedures to prevent accidental introduction of substances or energy
Effective isolation must be positive and physical — relying solely on closing valves is insufficient as they can be accidentally opened or may leak. Methods include physical disconnection of pipes, insertion of blank flanges (spades), electrical lock-out/tag-out, and securing mechanical equipment. Each isolation must be verified and tested.
Question 3: A competent person for confined space work is defined by the HSE as someone who has:
- At least 10 years of experience in any construction role
- Sufficient training, knowledge, experience, and skill to carry out the task safely (Correct answer)
- A university degree in occupational health and safety
- Completed an online confined space awareness module
Correct answer: Sufficient training, knowledge, experience, and skill to carry out the task safely
The HSE defines competence through a combination of training, knowledge, experience, and skill appropriate to the task. For confined space work, this includes understanding the hazards, knowing the safe system of work, being able to use equipment correctly, and recognising when conditions become unsafe.
Question 4: When reviewing a safe system of work for confined space entry, which of the following would indicate an inadequate system?
- Continuous gas monitoring is specified throughout the work
- Emergency rescue arrangements have been established and tested
- The risk assessment was last reviewed three years ago and the work process has since changed (Correct answer)
- Workers have received task-specific training and briefing
Correct answer: The risk assessment was last reviewed three years ago and the work process has since changed
A risk assessment that has not been reviewed despite changes in the work process is inadequate. Risk assessments must be living documents, reviewed whenever there is reason to believe they are no longer valid — such as changes in work methods, materials, equipment, or after an incident.
Question 5: Mechanical ventilation of a confined space before and during entry is used to:
- Keep workers cool and comfortable
- Dilute and remove hazardous atmospheres and provide a supply of fresh breathable air (Correct answer)
- Dry out wet surfaces inside the space
- Reduce noise levels from equipment inside the space
Correct answer: Dilute and remove hazardous atmospheres and provide a supply of fresh breathable air
Mechanical ventilation serves a critical safety function: it dilutes and removes toxic or flammable gases, replenishes oxygen, and maintains a safe breathable atmosphere. The ventilation intake must draw from a clean air source, and the system must be sized appropriately for the space volume and the hazards present.
Question 6: In a risk assessment, 'residual risk' in the context of confined space work refers to:
- The risk that remains after all control measures have been applied (Correct answer)
- The risk of chemical residues being present in the space
- The risk that existed before any assessment was carried out
- The risk of equipment failure only
Correct answer: The risk that remains after all control measures have been applied
Residual risk is the level of risk that remains after all reasonably practicable control measures have been implemented. In confined space work, even with a thorough safe system of work, some residual risk typically remains — this is why emergency rescue arrangements are always required as a final safety net.
Confined Space Training Certificate Risk Assessment and Safe Systems 2
A confined space entry permit should specify a time limit because: