7 DESIGN AND INSTALLATION All new and substantially modified steam raising boilers must be designed to satisfy all relevant requirements of the Pressure Equipment (Safety) Regulations (PER). When repairs or modifications, including changes to control systems or commissioning of a new system are undertaken, the risk assessments must be reviewed with a view to eliminating the risks or reducing them to a level as low as reasonably practicable (ALARP). 7.1 Design considerations Many trades and professions are involved in the design, construction, operation and maintenance of a boiler system, so it is essential that all equipment, instrumentation and controls are designed and installed by suitably qualified and experienced personnel in accordance with the manufacturers’ instructions. The design shall be based on the results of a risk assessment and relevant information from the appropriate design standards which provide further detail on the construction of shell boilers and their equipment. Boiler system designs shall address the following safety issues as a minimum: x Boiler house ventilation - ensure adequate air supply for combustion. Designs shall comply with IGEM UP/10, IGEM UP/16 and BS 6644 as appropriate; x The source of the boiler feed water, its effective treatment, and means for efficient monitoring of the water treatment plant, all in accordance with BG04, BS 2486:1997, BS EN 12953- 10 or the manufacturer’s instructions; x Electrical installation - designs to comply with BS 7671 IET Wiring Regulations. Note: Consideration should be given to the operating environment, ensuring that cable type, size, routing and connections will prevent erroneous operation & maintain the required integrity of the control system; x Boilers shall fail-safe, i.e. ensure boilers enter a safe mode under automatic control without requiring manual intervention. They shall also have a control integrity appropriate to their mode of operation; x Critical alarms relating to plant safety shall default to lock-out and require manual reset as defined by BS EN 12953-6; x Interruption of the electrical supply to water level and firing control equipment shall cut off the boiler automatically. Restart shall only be possible if the normal requirements for start-up are met and the boiler system has been designed to do so. Other considerations in boiler design include: x Appropriate types of controls and safety-related systems; x Site manning levels & competency; x Testing and maintenance requirements; x Normal, extreme and transient conditions including safe start-up and shut-down and management of boiler blowdown (see BG03); x Emergency procedures; x Access for operation and maintenance; x Relevant aspects of the Construction Design and Management Regulations (CDM). For guidance, three typical arrangements of steam boiler controls are outlined in the appendices. They are intended to be used in conjunction with the findings of the risk assessment, and represent suggested typical arrangements of certain steam boiler installations – they should not be used as design solutions or procurement specifications for new plant.
BG01 Guidance on the safe Operation of Steam Boilers Edition 2 – © 2019
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