Maximising safety in the boiler house

Published:  14 September, 2020

Boiler systems are required to comply with a raft of different legislation, including the Management of Health & Safety at Work Regulations 1999; the Pressure Equipment Regulations 1999; the Pressure Systems Safety Regulations 2000, and The Dangerous Substances and Explosive Atmospheres Regulations 2002. Derry Carr – CEA Immediate Past Chairman, and David Kilpatrick – CEA Director, report.

The Guidance documents from the Health and Safety Executive (HSE) on the safe operation of boilers, PM5 and SAFed’s PSG2, were withdrawn in October 2011 and have since been replaced by a more open document, INDG 436, which provides basic advice on the operation of steam boilers. However, the guidance in INDG 436 is both very specific on the responsibility of owners, managers and supervisors, and well-suited for use by those who may not have access to technical industry guidance.

BG01 is a boiler guide endorsed by the HSE, and prepared by the CEA and Safety Assessment Federation (SAFed), which details stringent guidance that boiler houses must be operated in accordance with, and runs in parallel with INDG 436. BG01 is applicable to any facility with an industrial or commercial steam boiler operating at between 0.5 and 32 bar gauge, and at a temperature between 110 and 400°C.

The second edition of BG01 was published in 2019 along with seven other guidance documents BG02 – BG08 covering many of the issues around safely managing the boiler house. If it’s a hot water boiler system, then BG02 covers Low Temperature Hot Water (LTHW) which is non PSSR and High Temperature Hot Water (HTHW) that falls within the PSSR.


Many hospitals and other organisations have gone down the route of installing biomass boilers with varying degrees of success, or not as the case may be. Often these biomass plants cause significant issues in several different ways including, fuel delivery, fuel handling, combustion, explosions, emissions etc. It is highly likely that many of the existing installations will not be able to meet the Medium Combustion Plant Directive (MCPD) which became law in 2018.

BG05 is the Guidance for Design and Operation of Biomass Systems and it is a guidance document intended to provide advice to clients, designers and those who operate and maintain commercial or industrial (i.e. non-domestic) biomass systems using wood in the form of pellets or chips.

Those involved in the procurement, design, construction and the ongoing operation (including maintenance) of biomass systems have duties to co-operate and share relevant information required for the development of a safe system of work. They have a number of legal responsibilities (Duties of care) and to comply with these duties they should possess or have access to good, current knowledge of health and safety legislation and practice, as well as ensuring personnel they employ are competent to carry out the required tasks safely.

The concepts governing safe design and operation are the same regardless of project size, from the smallest commercial installation to the largest power station. While BG05 focuses on the design and operation of new industrial and commercial installations, the information in this guide will also be relevant for smaller installations as well as the refurbishment or conversion of existing installations.

The content is most relevant to designers, building services designers and those practising as biomass specialists, e.g. for importers of biomass boilers. Those engaged in installing, operating or maintaining biomass systems will also find the content relevant and useful.

Please note that this document uses a hospital and their boiler installations as just one example of where guidance may well be required. The CEA has through its members investigated three biomass boiler explosions at hospitals in recent years, along with at least five other boiler explosions across general industry. Therefore, the following paragraphs are all relevant when operating boiler systems:

Due diligence

Although the standards set out in these guidance documents are not ratified by law, those who do not conform to them are required to set their own standards and due diligence processes that must be shown to be either equal to, or better than, these requirements.

One of the most important things to note for the owners of boiler plant, whether that be in healthcare or general industry, is that overall responsibility for the equipment lies, and remains, with them. BG01 states that: "While third parties such as maintenance contractors can be used to assist in achieving compliance with these legal obligations, the overall and legal responsibility remains on the owner/user, and cannot be contracted out, although there is scope for certain duties to be transferred (as set out in a written agreement) between the owner and user." This means that while a specialist contractor can take on the risk of operation and maintenance, all liability remains with the owner/operator.

Low awareness

This is a key point for boiler house managers, but awareness of the differences between what is laid out in current standards, and in the ‘old’ PM5, is currently very low. There is no guarantee that, where a utilities and energy management specialist is contracted to operate and maintain the boilers, they will automatically take on the liability on behalf of the customer. The exception is that, in some cases, plant and equipment remains the property of the outsourced company, with the resulting power sold to the customer.


A key driver within the regulations and the HSE more specifically is that all staff carrying out work should be competent to do so. But how do you prove that your staff are competent; you may also be using contractors, how do you know they are competent. A nationally recognised standard for boiler operations is BOAS (Boiler Operations Accreditation Scheme) for all operators and managers.

Gas is another area of concern in industry where the Gas Safety (Installation and Use) Regulations 1998 (GSIUR) say factories, sewage works, quarries etc. are exempt, and this has caused a lot of confusion. But there is a catch all clause which states that anybody working on gas must be suitably trained and assessed to carry out the work. To address this there is the I-GAS accreditation scheme at various levels that deals with this issue and helps prove competence.

Legally binding

One of the legally binding obligations is that boiler owners must have in place a ‘suitable and sufficient’ risk assessment, which is reviewed periodically. The responsibility for this lies with the plant owner, although of course advice from manufacturers, controls experts, and utilities management specialists, will ensure a thorough assessment. A full risk assessment must be in place for the boiler house, a particularly important factor where there is a planned alteration to the operating and maintaining regime of the boilers. In an environment where there are five or more employees, the findings of the risk assessment must be recorded.

The assessment must cover and address issues such as the likelihood of injuries from burns from hot water, steam, burners, or flues; electric shock; fuel escape; fire; asphyxiation, and the toxic effects from combustion products. It must also consider the position of the boiler. Taking into account the nature of some hospital sites, where plant and equipment can be located beneath buildings themselves, a thorough risk assessment is vital. It should cover the proximity of the boiler plant to premises and those occupying these; the proximity to the public and vulnerable people – including staff and visitors, and the potential impact on neighbouring sites in the event of an incident.

Competent person

PSSR calls for a Competent Person, recognised by the insurer, to regularly inspect the plant. This person carries a lot of influence; their opinion is what determines how often, within a 14-month period, the boiler must be inspected. In the event that the boiler house operations fall below standards set out in BG01, the Competent Person has the authority to demand that the steam boiler plant be inspected as regularly as once a month. Taking into account the time involved to strip down the boiler before re-installing and commissioning it again, up to a week can be wasted in downtime for the plant room and the subsequent cost associated with doing it.

If your boiler fails inspection for any reason (over 25% do fail inspection first time around) and you need to hire a temporary boiler, there is now BG08 to help you do this correctly and legally.

Ideally before you are in a position where you must hire in temporary boilers, make sure you have looked at and planned for this situation in your Technical Boiler House Risk Assessment. You may find that you don’t physically have the space or access. Solid piping is preferred and flexi hoses are not the recommended installation option. Can you get fuel, treated water, condensate, electricity and blow down for the temporary installation, a lot to plan for, but better to be prepared, even if you never have to use this facility.

Evolving technology

Inspection and boiler house attendance requirements have changed to take into account evolving boiler house technology such as remote monitoring, which is not covered in previous documents. The latest guidance advises on a wide range of control options, and recommends that personnel receive adequate training to perform their jobs safely and competently. BG01 recommends that operators and managers achieve the national industry standards through either the Certified Industrial Boiler Operator (CertIBO) scheme for operators, or the Diploma in Boiler Plant Operation Management (DipBOM) for managers. Both qualifications are part of the Boiler Operation Accreditation Scheme (BOAS).

It may not be relevant to your biomass plant if you don’t have gas on site but there is now the Industrial Gas Accreditation Scheme (I-GAS) that allows those working on gas outside the Gas Safety (Installation and Use) Regulations (GSIUR) to help prove competence.

Lower manning levels

Boiler houses have traditionally been fully attended, but with emerging technologies that provide greater automation, there is now provision for the plant to be visited once every 24 hours, and even less frequently – once every three days. If boiler owners are to feel confident of being able to cut down on the frequency of visits to this degree, they will need to have in place some very sophisticated automation. For example, high integrity self-checking probes must be in place to ensure that any feed water failure triggers a failsafe device in the boiler. The risk assessment will determine the minimum frequency of routine testing required. A high level of fire protection is clearly crucial, and alarms and shut-off for the fuel must be key considerations in the design and set-up of a boiler house.

Equipment with a monitoring role or safety function, which acts in a predetermined manner to prevent a dangerous situation from occurring, is available to enhance the automation of the boiler house. For example, a ‘low water level’ alarm prevents boiler operation when the water level falls, but allows automatic restart and resumption of operation once the water level has risen to a safe level. A second low-level lock-out is fitted as a precautionary measure should water levels fall too low, and, if triggered, this requires manual intervention by a trained boiler operator before the boiler can be reinstated. Safety systems should be designed according to BS EN 12953 and BS EN 61508, but, where electrical equipment is involved, BS EN 50156 should be applied.

Feedwater issues

A major cause of boiler failure lies with the treatment of the feedwater that enters the system. If this is not strictly controlled and monitored, there is a risk of limescale build-up, to the point of failure. Safe and efficient operation depends on the boiler remaining within its safe parameters during operation. A feedwater specialist should be employed to regularly check the water treatment plant and test the quality of its resulting water before it enters the system. But your own staff need to understand what the chemistry is doing in your boilers; to ensure you stay on top of the water treatment regime they should receive suitable and sufficient training. If unattended and not checked, it will potentially lead to a massive expense. If this is done correctly it can save thousands of pounds, if it’s done badly it can cost you thousands of pounds. BG04 will help you with this and the Steam Boiler Water Treatment training (SBWT) course is now available to help in training your staff.

While all combustion plant has an environmental impact, maintenance and operation of a boiler house according to best practice guidelines will help to support an energy efficient regime. This should include metering to monitor the boiler's efficiency; correct water treatment to ensure that this efficiency is not compromised; combustion analysis and burner adjustment to reduce energy loss, and the introduction of improvement devices such as economisers, variable speed drives, and flue gas dampers. Many installations are required to have an Environmental Permit, and operating the boiler outside of the conditions that this permit scheme applies is illegal. Smaller plants still fall under regulatory environmental control; the Clean Air Act 1993 covers local issues such as smoke and dust from the plant. MCPD is now law for any combustion plant >1MWth input - 1MW now and existing plants in a few years’ time.

Correct understanding vital

Using substantial volumes of energy, generated on site, is inherent in the proper functioning of many facilities. Yet without the correct understanding, interpretation, and implementation, of the law, the owner of the boiler stands to be liable for any failure. Accidents involving boilers have the potential to kill; as a result, the law is strict. The most senior person on site, the MD, CEO, Commanding Officer, etc. is ultimately responsible for the management of the boiler plant or consequences of an incident, even if they have never seen the boilers. They can of course delegate the responsibility to operate and manage the plant to a suitably trained and competent manager who must also have a suitably trained and competent operations team doing the day to day operations.

The Combustion Engineering Association would encourage all owners, users and operators of boilers or burners to join the CEA, which in turn provides access to the knowledge available on all aspects of boiler house management and steam systems in general.

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