When people think about confined space work, they often picture the work taking place inside the chamber, tank, pit or vessel.
In reality, some of the most important work happens before anyone even enters.
From identifying hazards and testing the atmosphere to preparing rescue arrangements and ensuring the correct permits are in place, confined space entry requires careful planning to protect everyone involved.
So, what actually happens before entry?
Step 1: Understanding the task
Every confined space entry begins with understanding exactly what work needs to be carried out.
Questions such as the following should be considered:
- What is the objective of the work?
- What hazards are already known?
- Has the space been entered before?
- Will specialist equipment be required?
- How long is the work expected to take?
Building a clear understanding of the task helps determine the safest method of completing the work.
Step 2: Identifying the hazards
No two confined spaces are the same.
Whether it’s a fuel tank, wet well, drainage chamber, interceptor, process vessel or storage tank, each environment presents its own unique risks.
A thorough risk assessment considers hazards such as:
- Oxygen deficiency or oxygen enrichment
- Toxic gases and vapours
- Flammable atmospheres
- Flooding or rising water
- Mechanical or electrical hazards
- Restricted access and egress
- Poor visibility
- Heat stress
- Engulfment by liquids or materials
Identifying these hazards early allows appropriate control measures to be put in place.
Step 3: Developing a safe system of work
Once the risks have been assessed, a safe system of work is developed.
This outlines exactly how the task will be completed safely and typically includes:
✔ Risk assessments
✔ Method statements
✔ Permit-to-work requirements
✔ Isolation procedures
✔ Communication methods
✔ Emergency arrangements
Everyone involved should understand the agreed procedure before work begins.
Step 4: Atmospheric gas testing
One of the most critical stages before entry is atmospheric testing.
Hazardous gases are often invisible and odourless, meaning dangerous conditions may not be obvious.
Using calibrated gas detection equipment, trained personnel check for:
- Safe oxygen levels
- Flammable gases and vapours
- Toxic gases such as hydrogen sulphide (H₂S) and carbon monoxide (CO)
If conditions are unsafe, entry should not proceed until the risks have been controlled.
Depending on the work being undertaken, continuous gas monitoring may also be required throughout the task, as atmospheric conditions can change unexpectedly.
Step 5: Equipment inspection and preparation
Before entering a confined space, all equipment should be inspected to ensure it is suitable, correctly calibrated and in good working order.
This may include:
- Gas detection equipment
- Harnesses
- Retrieval systems
- Tripods and winches
- Breathing apparatus (where required)
- Ventilation equipment
- Radios and communication devices
- Personal protective equipment (PPE)
Using properly maintained equipment is essential for protecting both those entering the space and the standby personnel supporting the work.
Step 6: Confirming competent personnel
Confined space work should only be carried out by individuals who have the appropriate training, experience and competence.
Depending on the nature of the task, this may involve:
- Confined Space Operatives
- Standby Personnel
- Supervisors
- Gas Testing Specialists
- Authorised Persons
Each person has a defined role in ensuring the work is carried out safely and in accordance with the agreed plan.
Step 7: Rescue planning
One of the most important questions to answer before entry is:
What happens if something goes wrong?
A rescue plan should always be developed before work begins—not during an emergency.
This includes considering:
- The rescue method
- Rescue equipment
- Emergency communications
- Site access
- Roles and responsibilities
- Escalation procedures
Having a suitable rescue plan in place can make all the difference should an incident occur.
Step 8: Final checks before entry
Only once all preparations have been completed should entry be authorised.
Before anyone enters, the team should confirm that:
✔ Risks have been assessed.
✔ Atmospheric testing has been completed.
✔ Equipment has been inspected.
✔ The permit to work is in place.
✔ Communication methods are understood.
✔ Rescue arrangements are ready.
✔ Everyone understands their role.
Only then can work begin with confidence that the appropriate safety measures are in place.
Safe confined space work starts long before entry
Confined space entry is about far more than the work carried out inside. It’s the planning, preparation and competence beforehand that help ensure every task is completed safely and efficiently.
At Marlin Environmental Services, our experienced teams support clients across the marine, industrial and commercial sectors with confined space entry, gas testing and Authorised Person services. By combining careful planning with competent personnel and robust safety procedures, we help our clients carry out high-risk work safely and in line with industry best practice.
Need support with confined space work?
Whether you require confined space entry, standalone gas testing or Authorised Person support, Marlin Environmental Services can provide experienced personnel to help plan and deliver high-risk work safely and efficiently.
