The Role of Written Schemes of Examination in Air Compressor Compliance
Industrial facilities in the UK rely on compressed air systems as a fundamental utility. The stored energy within these systems presents a significant, legally recognised hazard. To manage this risk, the Pressure Systems Safety Regulations 2000 (PSSR) mandate a critical document for many systems: the written scheme of examination. This document is the legal foundation for the safe operation and inspection of pressure equipment. A valid scheme must be certified by a Competent Person and in place before a new system is first operated.
If you are looking for air compressor compliance UK info, you have come to the right place. This article will outline what a written scheme of examination is, when you will need one and how it can help you avoid legal, financial and operational risk.
What is a Written Scheme of Examination?
A written scheme of examination is a formal document. It details the scope and frequency of inspections for a pressure system. Its purpose is to guarantee the integrity and continuous safety of pressure vessels and related machinery. By doing this, catastrophic failures brought on by the unchecked release of stored energy are avoided.
An inspection in accordance with the written scheme can be compared to a vehicle’s MOT. It is a legally mandated safety inspection performed by an independent expert. This is fundamentally different from routine maintenance, which is the system’s regular service. A service record is not a substitute for a formal examination report.
Is a WSE a Legal Requirement for an Air Compressor?
The requirement for a written scheme of examination is determined by the amount of stored energy in the system. Under PSSR 2000, a WSE is legally mandatory for any pressure system where the product of the vessel’s internal volume (in litres) and its safe working pressure (in bar) is 250 bar-litres or greater.
Calculating a System’s Bar-Litre Value
The calculation is Pressure (P) × Volume (V).
- V (Volume): The internal volume of the pressure vessel (air receiver) in litres, found on the manufacturer’s data plate.
- P (Pressure): The pressure in bar. This is the set pressure of the primary safety valve, not the compressor’s normal operating pressure. This value is typically stamped on the valve itself.
If a system contains multiple pressure vessels, each one must be assessed independently. Systems below the 250 bar-litre threshold are still covered by PSSR. Safe operation and proper maintenance remain legal requirements.
Quick Compliance Checklist
| Step | Action | Your Value |
| 1 | Find the vessel volume in litres (V) from the data plate. | |
| 2 | Find the safety valve set pressure in bar (P) from the valve. | |
| 3 | Multiply P × V. | |
| 4 | Is the result 250 or greater? If yes, a WSE is required. |
The Role of the ‘Competent Person’
The PSSR framework relies on the ‘Competent Person’. This is an individual with the necessary practical knowledge, theoretical understanding, and experience to carry out examinations. This person has two key functions:
- Drafting or certifying the written scheme of examination.
- Conducting the examinations specified in the scheme.
According to UK legislation, the Competent Person’s activity must be conducted with total independence and objectivity. This guarantees that all assessments stay objective and unaffected by operational or financial constraints that can compromise their correctness. The user or system owner is in charge of choosing a qualified inspector for that. Objective evidence of qualification is provided by the holder’s verifiable qualifications and accreditation to a relevant standard, for example, UKAS accreditation to BS EN ISO/IEC 17020:2012.
What a Written Scheme of Examination Must Contain
A compliant written scheme of examination is a detailed inspection plan. It must be reviewed after any significant modifications or repairs. The scheme must specify:
- All parts of the system are to be examined, including pressure vessels, pipework, and protective devices.
- The nature of the examination required for each part.
- The maximum interval between examinations.
- Critical parts that require re-examination by a Competent Person after any modification.
- Any preparatory work is needed to conduct the examination safely.
- The name of the Competent Person certifying the scheme and the date of certification.
A thorough scheme offers a precise road map for guaranteeing routine inspections of the compressed air piping system and all of its essential parts.
Typical Compliance Issues and Their Fixes
Businesses often encounter similar hurdles when managing PSSR compliance.
- Challenge: Misidentifying system boundaries. This involves failing to include all relevant pressure vessels or critical pipework.
- Solution: An expert site audit using system diagrams from tools like Atlas Copco’s AIRScan clearly defines these boundaries.
- Challenge: Missed inspection schedules. This renders the system non-compliant.
- Solution: Automated alerts for approaching service and inspection due dates are provided by monitoring systems such as Atlas Copco’s SMARTLINK.
- Challenge: Using unqualified personnel. An in-house maintenance engineer may not legally meet the definition of a ‘Competent Person’ for statutory examinations.
- Solution: Examinations are administered by qualified, unbiased engineers when you work with a recognised supplier.
The Consequences of Non-Compliance
Failing to have a valid written scheme of examination in place is a criminal offence. The Health and Safety Executive (HSE) takes a firm stance, with a conviction rate of approximately 93% for prosecuted cases and an average fine that has risen to £145,000.
The risks extend beyond legal penalties:
- Invalidated Insurance: An incident involving a non-compliant system could void engineering and liability insurance.
- Operational Downtime: An HSE prohibition notice can shut down operations instantly.
- Human Cost: Compliance exists to prevent serious or fatal injuries from equipment failure.
Achieving Compliance and Operational Efficiency
Control Gear is an Atlas Copco Premier Distributor providing technical support for PSSR compliance across South Wales and the West. Compliance processes are integrated with preventative maintenance to improve efficiency and extend equipment lifespan.
A Benefits of a Compressed Air Audit is that it can identify system risks and form the basis of a compliant WSE. A Compressed Air Leak Detection survey can reduce energy costs. For specialised applications, services like Breathing Air Quality Testing help meet all relevant standards.
The Importance of Regular Air Compressor Servicing is the foundation of this strategy, ensuring a system runs reliably and safely.
Make sure your compressed air system is safe, efficient and fully compliant. Book your compliance audit today or talk to our expert team about preparing and certifying your Written Scheme of Examination.