What is a Written Scheme of Examination (WSE) for PSSR?

Everything You Need to Know About Pressure Systems Safety Regulations

If your business operates pressure systems such as air receivers, compressors, pressure vessels, or steam systems, you've probably heard the term Written Scheme of Examination (WSE).

But what exactly is it, who needs one, and why is it a legal requirement?

Many businesses only discover they need a Written Scheme of Examination when purchasing new equipment or during a Health and Safety Executive (HSE) inspection. By then, failing to have one in place could put your business at risk of non-compliance.

In this guide, we'll explain everything you need to know about Written Schemes of

Examination, how they fit into the Pressure Systems Safety Regulations (PSSR), and why they're essential for keeping your workplace safe.

What is a Written Scheme of Examination?

A Written Scheme of Examination (WSE) is a formal document required under the Pressure Systems Safety Regulations 2000 (PSSR).

It sets out exactly how your pressure system should be examined to ensure it remains safe throughout its working life.

Rather than simply stating that equipment should be inspected, the scheme identifies:

• Which parts of the pressure system require examination

• The type of examination required

• The frequency of examinations

• Any special inspection requirements

• The procedures needed to maintain safety

  
  

Think of it as a maintenance roadmap that ensures your pressure equipment continues to operate safely and legally.

What is PSSR?

The Pressure Systems Safety Regulations (PSSR) were introduced to protect people from the dangers associated with pressurised equipment.

Pressure systems can store enormous amounts of energy.

If they fail unexpectedly, the consequences can include:

• Serious injury

• Equipment damage

• Production downtime

• Business interruption

• Legal action

  
  

The regulations exist to ensure these systems are properly maintained and regularly examined by competent persons.

Which Equipment Requires a Written Scheme of Examination?

Many businesses are surprised by how much equipment falls under PSSR.

Examples include:

Air Receivers

Often connected to compressed air systems used in factories, workshops, engineering facilities, garages, and manufacturing plants.

Air Compressors

Many compressed air installations require a Written Scheme of Examination.

Pressure Vessels

Used throughout manufacturing, food production, pharmaceuticals, engineering, and industrial processing.

Steam Boilers and Steam Systems

Steam operates under extremely high pressure and requires careful management.

Refrigeration Systems

Certain refrigeration systems operating above specified pressure limits may also require examination.

Pipework and Associated Safety Devices

Pressure relief valves, pressure gauges and associated pipework can also form part of the Written Scheme.

Who Writes a Written Scheme of Examination?

The Written Scheme must be prepared—or certified as suitable—by a Competent Person.

A competent person has the technical knowledge, qualifications, and experience necessary to assess pressure systems and determine appropriate inspection requirements.

They will assess:

• Operating pressure

• Equipment design

• Materials

• Age

• Operating conditions

• Potential risks

• Manufacturer recommendations

  
  

Every pressure system is different, so each Written Scheme should be specific to the equipment being used.

What Does a Written Scheme Include?

Although every system is different, a typical Written Scheme will include:

Equipment Identification

A detailed list of equipment covered by the scheme.

Examination Intervals

The required inspection frequency for each component.

Parts to be Examined

Critical pressure-retaining parts including:

• Pressure vessels

• Air receivers

• Pipework

• Safety valves

• Pressure relief devices

  
  

Examination Method

Details of how examinations should be carried out.

This may involve:

• Visual inspection

• Internal examination

• External examination

• Non-destructive testing where required

  
  

Special Requirements

Any additional safety precautions or testing procedures necessary for the specific system.

How Often Does a WSE Need Reviewing?

The Written Scheme itself does not usually have a fixed expiry date.

However, it should be reviewed whenever there are significant changes, including:

• Installation of new equipment

• Major repairs

• System modifications

• Changes to operating pressure

• Changes in operating conditions

  
  

Your inspection provider can advise when updates are required.

What Happens During a PSSR Examination?

During a scheduled examination, a competent engineer will inspect the components identified within the Written Scheme.

Typical checks include:

• Corrosion

• Fatigue

• Cracking

• Weld condition

• Pressure relief devices

• Gauges

• Structural condition

• General safety

  
  

Once complete, you'll receive a report detailing:

• The condition of the equipment

• Any defects found

• Recommendations

• Whether the equipment is safe to remain in service

  
  

What Happens if You Don't Have a Written Scheme?

Operating qualifying pressure systems without a suitable Written Scheme may result in:

• Non-compliance with PSSR

• Increased safety risks

• Equipment failure

• Enforcement action

• Production downtime

• Insurance complications

  
  

More importantly, pressure system failures can have catastrophic consequences if equipment is not properly maintained.

The Benefits of Having a Written Scheme of Examination

A professionally prepared WSE offers far more than legal compliance.

It helps businesses:

✔ Protect employees and visitors

✔ Reduce the likelihood of pressure system failures

✔ Improve equipment reliability

✔ Plan maintenance more effectively

✔ Extend equipment lifespan

✔ Demonstrate compliance during HSE inspections

✔ Support insurance requirements

A proactive inspection programme is almost always more cost-effective than dealing with an unexpected failure.

Why Choose a Professional Inspection Company?

A competent inspection company can provide:

• Written Schemes of Examination

• PSSR inspections

• Air receiver inspections

• Pressure vessel examinations

• Compliance reporting

• Practical advice on maintaining pressure systems

  
  

Working with experienced engineers gives you confidence that your equipment remains safe, compliant, and operating efficiently.

Frequently Asked Questions

Is a Written Scheme of Examination a legal requirement?

Yes. Where required under the Pressure Systems Safety Regulations, qualifying pressure systems must have a suitable Written Scheme of Examination prepared by a competent person.

Does every air compressor need a WSE?

Not always. Whether a Written Scheme is required depends on factors such as the type of system, operating pressure, stored energy, and how it is used.

How long does a PSSR inspection take?

Inspection times vary depending on the complexity and size of the pressure system. Small air receiver inspections may take less than an hour, while larger industrial systems may require significantly longer.

Can I write my own Written Scheme?

Only if you meet the legal definition of a competent person with the appropriate knowledge, qualifications, and experience. Most businesses choose an independent inspection specialist to ensure compliance.

Need a Written Scheme of Examination or PSSR Inspection?

Whether you operate a single air receiver or a complex industrial pressure system, having the correct Written Scheme of Examination is essential for compliance and safety.

Our experienced inspection engineers provide professional PSSR inspections, Written Schemes of Examination, and expert compliance advice for businesses across a wide range of industries.

📩Get in Touch

Contact us today to discuss your pressure systems, arrange an inspection, or request a Written Scheme of Examination tailored to your equipment.

📧 info@mechinspect.co.uk 📲 0330 043 3448