The safe and efficient operation of boilers and domestic water heaters is essential for the smooth operation of most institutional and commercial facilities. Improvements in designs and control systems have made today’s units safer and more efficient than ever.
But good design practices alone do not ensure safety and efficiency of boilers. In addition to good system designs, an ongoing inspection and testing program carried out by a well-trained staff of technician’s results in safe and efficient boiler operations. Maintenance and engineering managers who ignore any one of these elements run the risk of compromising not only safety and efficiency but also the operation of the boiler.
The word ‘boiler’, in everyday use, covers a wide range of equipment, from simple domestic hot water boilers to boilers housed within a power generation plant to convert fossil fuel to electricity. Boilers means any closed vessel in which for any purpose steam is generated under pressure greater than atmospheric pressure and also means any economizer used to heat water being fed into any such vessel, any super heater used for heating steam and any fitting directly attached to such vessel that is wholly or partly under pressure when steam is shut off, and any vessel in which oil is heated at a pressure greater than atmospheric pressure.
Different types of boiler used in industries according to their requirement like Power Boiler, Heating Boiler, Electrical Boiler, High Pressure Boiler, High-Temperature Boiler etc.
Energy management of boilers is sensible to minimize operating costs & emissions, to facilitate safe operation and long plant life. An efficient, reliable boiler is an essential requirement for many businesses, and the downtime caused by a failed boiler can have a major effect on production, plant and people.
- Control System Malfunction.
- Fire Side Explosion.
- Loss of Power Supply.
- Loss of Water.
- Unauthorized Access.
- Unauthorized Modifications & Repairs.
- Overheating Due to Excessive Scale.
This will require a systematic assessment of any risks that may be present and the control measures in place to address them. Risk assessments must be reviewed periodically and when there is a significant change e.g. a system variation, change in operating parameters or manning levels etc. the outcome of any reviews should also be recorded. The exact considerations will depend on the site (site-specific) but may include the following:
- The boiler specification, condition and its associated plant.
- The manner in which the boiler is operated and maintained.
- Any safe systems of work, including management and supervision.
- How competent the workers are, and how they have been trained?
- How reliable the electronic control system is?
- How regularly boiler is examined and tested?
Accident means an explosion of a boiler or any damage or occurrence to or in a boiler that weakens the boiler and renders it liable to explode or collapse. Accidents involving exploding boilers have killed people, damaged plant and affected production. These accidents resulted from problems such as inadequately designed boilers, wrongly sited or wrongly installed boilers as well as boilers that were not correctly operated or maintained. Types of injuries from boiler explosion:
- Burns from hot water.
- Steam, burners and flues.
- Electric shock.
- Fuel escape.
- Asphyxiation and toxic effects from combustion products.
Boiler House Safety
The boiler is only one piece of equipment within the boiler house and there will be several other issues that require compliance with other legislation, for example ventilation, fire and gas. A number of different technical personnel may therefore need to be involved in aspects of boiler house safety, e.g. operation and maintenance staff. It is essential that the owner/manager of the site ensure there is adequate communication between these people, even though they may not be directly employed by owner/manager:
- All equipment, instrumentation and controls must be installed and maintained by suitably qualified and experienced personnel in accordance with the manufacturer’s instructions.
- Fire detection, fire alarm and automatic shut-off of the fuel should be provided. For gas firing, gas detection and alarm should also be considered.
Safety procedure included inspection, maintenance, testing and responsibilities. These efforts will establish a safety environment in boiler house.
An inspection of boiler and its auxiliary equipment has two purposes:
- It verifies the conditions of the boiler so that appropriate remedial action can be done if required.
- It familiarizes the competent Person with equipment so that proper control on the operation of the boiler can be achieved.
If a boiler is not operated within its design limits, it increases the risks of fatigue, stress and corrosion, which could eventually lead to leaks, ruptures and, in extreme cases, explosions. Similarly with feed water, incorrect water treatment can lead to scaling, which will again damage the boiler and could lead to premature or catastrophic failure. For this reason proper maintenance of equipment is necessary:
- Boiler system should be properly maintained and in good repair, so as to prevent danger, and should take account of manufacturers’ instructions in accordance with Regulation.
- All maintenance requirements and activities should be fully documented, including the frequency that maintenance should take place.
- If scale is found in boilers, the water treatment system should be checked for correct operation and appropriate corrective action taken.
Routine testing of boiler controls, limiting devices and feed water quality is essential to ensure the boiler continues to be safe, reliable and efficient. For example, where the water quality is poor and there is a high dependence on water treatment, more frequent testing of the water and blow down of the boiler may be required.
The duties of the boiler operator include:
- Implementing the boiler manufacturer’s recommendations with regard to starting up from cold, and for all the other aspects of the boilers operation, use, maintenance and cleaning etc.
- Carrying out all functional tests of limiters & controls where required, before the boiler is left unattended and at all specified frequencies and in the specified manner.
- Checking burner and associated equipment.
- Responding to alarms and taking appropriate action.
- Carrying out the recommended water quality tests, routine water treatment, recording
- The results and making adjustments where necessary in accordance with established standards.
Responsibility of Operator
- Boiler operators should ensure that they hand over the boiler to maintenance personnel in a safe condition.
- On completion of maintenance, the checking of all controls and alarms should be verified by the boiler operator in the presence of the maintenance personnel before the boiler is placed on line.
- If the maintenance is carried out at the same time as the boiler examination, the controls and alarms will also be verified by the CP.
Employers must ensure that all personnel possess sufficient knowledge of the boiler systems on which they work to perform their duties properly. It includes:
- Boiler operation including start-up and shut-down.
- Boiler & burner controls and failure modes, taking account of fuel/s used.
- Feed water/boiler water analysis.
- Condensate drainage and water-hammer.
- Actions to be taken in an emergency and the consequences of inappropriate action.
- Responsibilities of all parties involved and legal aspects.
- Site specific training plus documented written and oral examination on completion of course.
While installing and on-going energy generation the operator should be aware of the all technical aspects and change into the system and ready to tack safe action against any flaw. The following are the safety precautions should be taken and maintained:-
- Never try to repair any faulty electric circuit. The repair should be carried out by a registered electrical worker only.
- Personnel monitoring boiler alarms from on-site and off-site locations.
- The safety valve is the most important valve on the boiler. Safety valves prevent dangerous over pressurization of the boiler. Safety valves are installed in case there is failure of pressure controls or other devices designed to control the firing rate. All safety valves should be kept free of debris by testing the safety valve regularly.
- The concentration of solids in the boiler should be measured and the boiler blown-down at such intervals as necessary to maintain established limits. Blow-down valves are placed at the lowest point of the boiler for the purpose of blowing sediment or scale from the boiler. They should be maintained in good working order and are to be opened and closed carefully when used.
- Maintain the fire as uniformly as possible to avoid an excessive rate of combustion, undesirable variations in temperature and possible explosions. The destructive force in a boiler explosion is caused by the instant release of energy stored in the water as heat.
- Keep all connections and valves clear. Test by blowing down the water glass and water column regularly. Gauge cocks or tri-cocks should also be blown regularly.
- Protective Clothing: A face shield along with safety glasses provides eye protection when working with feed water chemicals.
- Chemical Safety: Containers that contain hazardous materials must be labeled, tagged, or marked.
- Lockout/Tag out: Lockouts and tag outs are applied to equipment to prevent injury from energized circuits and equipment operation during maintenance and repair.