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Importance of Welding for Steam Boiler Manufacturing

Friday, 16 September 2022 / Published in Boiler, Steam Boiler

Industrial steam boilers are irreplaceable in almost every industry throughout the world. The energy holding capacity and safety in using steam is a major cause of steam boilers being an ideal choice for process operations. Therefore, industries consider every factor while selecting a steam boiler manufacturer. The quality of the steam boiler is a crucial aspect in deciding on a boiler company. The precision and utilization of high-tech machinery play a vital role in ensuring the superior quality of steam boilers. A steam boiler is manufactured of three primary components i.e. a cylinder, a base, and a cover. Rakhoh Boilers, as a leading steam boiler manufacturer, ensures that the steam boilers are fabricated with utmost safety and precision with excellent welding.

Welding in Steam Boilers:

Welding is a process involving fabrication that joins materials, usually metals or thermoplastics, through fusion, varying from lower temperature metal-joining techniques like brazing and soldering that do not melt the base metal. Combined with melting the base metal a filler material is usually added to the joint, forming a pool of molten material to cool and form a joint. It is generally stronger than the base material. Pressure may also be used jointly with heat or by itself for producing a weld.

Contrary to brazing and soldering that do not involve the melting of base metal, welding includes a high heating process that melts the base material by usually adding filler material. As a result, the high heat causes a weld pool of molten material. Pressure is also used for producing a weld along with the heat or by itself. It also utilizes a shielding gas for protecting the melted and filler metals from contamination or oxidation. A weld joint in a steam boiler is designed for withstanding the subjected forces during its lifespan. Therefore, the design of the joint is decided by the type and load magnitude on the weld.

The welding process is generally categorized as:

Gas welding: Gas welding includes oxy-acetylene gas welding and hydrogen gas welding.

Arc welding: Arc welding includes metal arc welding (SMAW ), submerged arc welding (SAW ), gas metal arc welding (MIG, MAG), electrode slag metal arc welding, tungsten inert gas welding (TIG), flux-cored arc welding(FCAW ), etc.

Resistance welding: Resistance welding includes percussion welding, seam welding, and spot welding.

Thermit welding: Thermit welding involves producing heat by exothermic chemical reactions.

Solid-state welding: Solid-state welding involves friction welding, forge welding, pressure welding, etc.

Special welding process: Special welding processes include electron beam welding, diffusion welding, plasma arc welding, underwater welding, ultrasonic welding process, etc.

Requirements of Tube Welding in Steam Boilers:

The characteristics of boiler tube welding include,

  • Large quantity of tubes
  • Radial and axial clearances
  • Tubes made of carbon steel or other metal with a high strength-to-weight ratio
  • Thick boilerplates of up to 900 mm

    • The strength and consistency of the weld are pivotal considerations in determining the ideal way to weld the pressure vessel tubes as the tubes carry high-pressure steam or liquids in a flowing pattern that can cause a loss in efficiency due to turbulence or distortion.

    One of the most crucial aspects of welding boiler tubes is to determine the ideal option between orbital welding and manual welding. Factors like industrial application tube quantity and safety should be the paramount priority. Therefore, manual welding is the least likely option because of the lack of accessibility.

    Additionally, the welder must decide the best technique to apply. As gas-shielded welding processes are more consistent than other techniques, MIG and TIG are the ideal alternatives. However, MIG leads to the spattering of filler that negatively impacts the weld quality and bead appearance. On the other hand, TIG uses tungsten electrodes, producing the highest purity welds. Narrow Groove TIG or Thick Wall welding processes are best suited for the thick wall boiler applications found commonly in power plants.

    Tungsten Inert Gas Welding with tungsten electrodes results in the highest-quality and consistent welds. Implementing an orbital welding process reduces the lack of accessibility, making it easier for consistency throughout the welding. However, attributes like good heat control, process stability, and fixed position tube welding capability with automated controls should be considered by steam boiler manufacturers for welding machines.

    Common Hazards with Welding:

    Welding leads to hazardous consequences for both welders and those working in the vicinity. Therefore, it is essential to ensure precautions to prevent accidents and injuries.

    Electric Shock:

    As a welder touches two metal objects with a voltage difference leads to the electric shock that can cause severe injuries or death. It is further classified as,

    Primary shock:
    It ranges from 230 to 260 volts that occur by having direct contact with the inside of welding equipment and other grounded metals. Primary shock is extremely hazardous

    Secondary shock:
    It is the most common type of shock occurring while touching the electrode circuit that ranges from 20 to 100 volts

    Prevention for Electric Shock:

  • Avoid touching the metallic parts of the electrode holder with damp skin or clothing.
  • Rubber mats or other insulation for welders.
  • Wear dry gloves.
  • Only qualified technicians should handle welding equipment.
  • Proper inspection of welding equipment and electrode holder.

    • Fire Hazards:

    Welding sparks spray up to 35 feet and may cause fire hazards, severely impacting the workers with grease on their clothing.

    Prevention for fire hazards:

  • Ensure the availability of fire extinguishers.
  • Ensure spacious working space.
  • Store combustible substances and flammable chemicals away from the working space.
  • Use fire-resistant shields.
  • Dusty locations can generate additional risks when welding.

    • Fumes and Gases:

    Welding introduces the personnel to gaseous fumes like ozone, nitrogen, and carbon monoxide that may cause asthma, pneumonia, or cancer.

    Prevention for Fumes and Gases:

  • Minding the head from the fume plume.
  • Ventilation and local exhaust for harmful gases.
  • Use approved respiratory devices.
  • Monitor contaminant levels to determine air quality

    • Physical Hazards:

    Various physical hazards are involved in welding activities like burns, cuts, crushed fingers, and eye damage.

    Prevention for physical hazards:

  • Welding helmets with side shields for protection against UV radiation, particles, debris, and chemical burns.
  • Respirators for protection against gases and fumes.
  • Fire-resistant clothing for preventing burns caused by heat, fire, and radiation.
  • Ear protection for preventing workplace noise hazards and vibration.
  • Boots and gloves to protect welders from hazards like an electric shock and falling objects.

    • Conclusion:

    Rakhoh Boilers is a leading steam boiler manufacturer since its inception in 1983. We are a trusted name in over 26 countries for delivering efficient steam boilers, waste heat recovery systems, thermic fluid heaters, boiler accessories, and boiler services of world-class quality.

    For more details, visit www.rakhoh.com

    Importance of Heat Exchanger and Tips to Increase its Efficiency

    Thursday, 15 September 2022 / Published in Boiler, Steam Boiler

    Steam boilers are imperative for the operation of the process and manufacturing industries. Steam is vital for heating and processing purposes in industries, and therefore, a steam boiler consists of various components that ensure the steam generation takes place seamlessly. One such component in the boiler system is a heat exchanger. Heat exchangers are long tubes of metal with openings at both ends. It enables the heat transfer from the gas in the burners that produce toxic byproducts when it burns. Heat exchangers are not coils but are usually made from steel sheet metal and enable the gas-to-air exchange.

    Importance of Heat Exchangers in Steam Boilers:

    In a boiler system, the hot-water radiators harness heat from hot gas jets, but initially, the water needs to absorb the heat energy from the gas. The heat exchanger safely allows the passing of heat energy from gas to the water. If water is heated directly from the gas, the flames would be extinguished by the water. The basic principle of the heat exchanger is that it allows the transferring of the heat without transferring the fluid (liquid or gas) carrying the heat. The surfaces through which heat passes are called heat transfer surfaces. Heat transfer takes place in the steam boiler, where hot gasses from the combustion of fuel transfer levels of intense heat through the steam boiler tubes to produce steam.

    The build-up of any hindering material such as scale, corrosion products, or micro-organisms on heat transfer surfaces slows down the heat exchange.

    Indications of Issues in Heat Exchangers:

    Several indicators point towards issues in heat exchangers and require prompt actions. Some of them are as follows,

    Black Soot:

    Black soot around the furnace is a clear sign that the gas is not burning properly. Unhealthy and incomplete combustion leads to dirty soot around the furnace. It usually leads to a damaged heat exchanger or an issue with the burner or furnace flame.

    Unpleasant Smell:

    Although gasses such as carbon monoxide are odorless, any strange or unpleasant odor near the furnace or air ducts requires professional attention. Cracked heat exchangers can leak combustion gasses into the boiler system that can cause a clear and present odor. In such situations, it is crucial to immediately turn off the heating system and seek professional help to diagnose the situation.

    Water Surrounding the Furnace:

    If water is found on the floor near the furnace, it may indicate a problem with the heat exchanger. Whether it is condensation or a cracked heat exchanger, seek professional help right away to determine the cause.

    Outdated System:

    If there are complaints of other aging problems with the furnace, such as wear and tear, loud noises, it is ideal to have a professional diagnose the entire steam boiler system.

    How to Increase the Efficiency of the Heat Exchanger in Steam Boiler?

    The ideal method to reduce the operating expenses in a process plant is by using and maintaining energy-efficient equipment

  • The major heat loss in the boiler heat exchanger is caused by the boiler water. Therefore, it is necessary to ensure that heat exchangers generate as minimal exhaust or flue gas as possible. Maintaining the minimal temperature within the heat exchanger accelerates the steam boiler efficiency.
  • Using an economizer allows the facilities to use the otherwise wasted hot exhaust gas for heating the feed-water. It helps in saving fuel and preventing the hazardous effects of feeding the steam boiler with cold water.
  • Tune the burner regularly as boiler efficiency is also impacted by insufficient air. Proper combustion needs sufficient oxygen in the boiler. In the case of insufficient air, the carbon within the fuel is incompletely oxidized, leading to carbon monoxide production. It causes a reduction in fuel efficiency and less heat because fuel is not burned completely. Less air also generates smoke, soot, and carbon monoxide that cause hazardous conditions.
  • Installation of a VFD (variable frequency drive) offers significant power savings due to the use of circulation pumps and fans that leads to controlled flow.
  • Insulate valves to prevent valve exposure and avoid heat loss that can make boiler rooms unbearably hot. Insulating the boiler valves helps in increasing boiler room comfort and reducing burn risks.
  • Maintaining a clean waterside that is free of leaks. It requires regular and proper water treatment and inspection of mud legs or drums as it ensures efficient heat transfer from metal to water. If the steam boiler is not blown-down regularly, the scale accumulates on the heat transfer surface, hindering the heat transfer.
  • Reducing excess air for efficient combustion as insufficient air could lead to incomplete combustion. Excess amounts of air can cause different inefficiencies, such as reduced combustion.
  • Removal of the soot and build-up on the fireside of the boiler tube. It is found particularly in older boiler heat exchanger equipment. Soot and grime in the boiler tube reduce the heat transfer rate and cause the equipment to operate harder, thus increasing fuel use.
  • Recover heat through the blowdown. The blowdown valve eliminates boiler water consisting of both insoluble and soluble solids. It helps to reduce the level of dissolved solids that leads to boiler scale. However, it also removes hot water, which in turn wastes energy. A blowdown heat exchanger or a flash tank aids in recovering lost energy and improving the efficiency of the boiler system.

    • Reduce carry-over to avoid impurities and ensure proper levels of BTU content at end-use.

    Impact of poor heat transfer in the steam boiler:

  • A 5% reduction in heat transfer leads to the plant achieving only 95% of its potential output.
  • An increase in energy consumption as pumping costs increase because water must be circulated more rapidly in an attempt to restore cooling efficiency.
  • Overheating causes tube failures and other system components. It requires immediate shutdown of the equipment as it may cause injury to personnel working in the area of a failure.

    • Conclusion:

    Rakhoh Boilers are one of the leading manufacturers of industrial steam boilers in Pune since 1983. Over 38+ years, Rakhoh has successfully installed more than 3000 boilers in 26 countries worldwide. We also provide excellent boiler services like energy audit, boiler automation, steam trap assessment, annual boiler maintenance, fuel conversion, etc.

    For more details on our products and services, visit www.rakhoh.com

    Priming and Foaming in Steam Boilers | Causes, Effects, and Prevention

    Wednesday, 14 September 2022 / Published in Boiler, Steam Boiler

    The manufacturing and process industries throughout the world require steam boilers for processing operations. Steam boilers are undoubtedly irreplaceable equipment in the industries for heating, drying, and sterilization purposes. Plant managers ensure that the boiler systems are functioning smoothly and delivering optimum productivity. Regular maintenance and following standard guidelines are important to ensure the safety of the process plant and hassle-free operations. However, some boiler problems are inevitable and require prompt action to avoid significant losses or harm. Among many issues occurring in steam boilers, priming and foaming are the two most commonly found boiler problems. Let us understand both concepts in detail.

    Priming:

    As the steam boiler generates steam rapidly, some water particles are carried along with the steam. The process of formation of wet steam is known as priming. Due to the carryover of water droplets in the steam, the energy efficiency of the steam is reduced. It leads to salt crystals deposition on the superheaters and turbines. Improper construction of steam boilers, sudden fluctuation in steam demand, and excessive ratings are some of the primary causes of priming.

    Minute drops entrainment is unavoidable in steam boilers. If the boiler water carryover is excessive, it results in steam-carried solids producing turbine blade deposits. The composition of the deposits is similar to the dissolved solids in the boiler water. Since priming is a major cause of the high level of boiler water carryover, it consequently leads to the failure of superheaters. Priming takes place due to the viscosity of water and its possibility of foaming. These properties depend on the alkalinity, presence of organic substances, and total dissolved solids or TDS. The level of priming is related to the design of the steam boiler and the steaming rate.

    Priming leads to the deposit formation in the valves that causes overheating and corrosion in superheaters. It affects the heat transfer that results in low quality of processed product, higher level of steam consumption, and lowers the overall lifecycle of the steam boiler system.

    Causes of Priming:

  • Large amount of dissolved solids like alkali sulfates and chlorides present
  • Sudden boiling operation
  • Inadequate amount of steam space
  • Improper design of steam boiler
  • Sudden acceleration in steam-production rate

    • Effects of Priming:

  • Reduction in boiler efficiency
  • Increase in maintenance costs
  • Lowers the lifespan of the machinery parts

    • Prevention for priming:

  • Improved steam boiler design
  • Introducing mechanical steam purifiers in boiler systems
  • Maintaining low water levels in the boiler
  • Utilization of soft water
  • Reducing the amount of dissolved salts in the feedwater

    • Ensuring chemical presence in the boiler water does not exceed the required amount

    Foaming:

    Foaming is the unrelenting formation of bubbles or foam in the steam boiler that does not cease easily. It is caused due to the oily substances in water that reduce the surface tension in the boiler water. The contamination of the steam with solids in boiler water causes water carryover. The froth or bubbles formed at the surface of the boiler passes out with the steam. The phenomenon, known as foaming, is caused by a high concentration of solids present in the boiler water. It has been found that particular substances such as alkalis, fats, oils, grease, and specific types of organic matter are specifically instrumental in foaming.

    In addition, the suspended solids accumulated in the surface film that surrounds the steam bubble result in a persistent deposition. It leads to resistance in the bursting of a steam bubble that builds up foam. It has been observed that finer suspended particles accumulate on a higher level in the bubble.

    Causes of Foaming:

  • High level of dissolved solids in boiler water
  • Increase in water level
  • Higher impurities
  • High presence of chemicals

    • Effects of Foaming:

  • The actual height of the water column cannot be accurately estimated, which makes the maintenance of the pressure part challenging.
  • The dissolved salts in the water passed by the wet steam damages the turbine blades and superheaters, resultantly reducing their efficiency
  • The dissolved salts in the water may impact the other machinery parts that decrease the overall lifespan of the steam boiler.

    • Prevention of Foaming:

    Introducing anti-foaming agents such as castor oil, tannic acid, gallic acid, etc.
    Administrating compounds like sodium aluminate for eliminating oil from the boiler water

    Since 1983, Rakhoh Boilers has emerged as a trusted boiler manufacturer in Pune, delivering efficient and reliable industrial steam boilers in over 26 countries globally. We manufacture superior quality products like steam boilers, waste heat recovery boilers, thermic fluid heaters, and boiler accessories. We are renowned for our excellent after-sales services like energy audit, boiler automation, steam trap assessment, annual boiler maintenance, etc., to ensure the hassle-free efficiency and productivity of the steam boilers.

    To learn more about our products and services, visit www.rakhoh.com

    Daily Boiler Maintenance Practices For Industrial Boilers

    Tuesday, 06 September 2022 / Published in Boiler, Steam Boiler

    Process and manufacturing industries with industrial boiler systems would understand the importance of seamless process operations for the industry’s overall success. At the same time, if industries aim to get the most out of the boiler system, it has to take care of it. That is why routine boiler maintenance is so essential. There are several important steps that plant managers need to perform every day if they plan to maximize the efficiency and longevity of the industrial boiler. Performing these simple steps can extend the boiler lifespan and schedule predictive boiler services before any major issues arise.

    Daily maintenance is necessary to keep the boiler in good shape and ensure the safety of the process plant workers. Daily maintenance can prevent the build-up of soot and scale, both of which are harmful to the efficiency of the industrial boiler. Consequently, efficiency is critical for the boiler because equipment failures can be hazardous and usually result in a loss of productivity and revenue. In extreme circumstances, lack of boiler maintenance can lead to explosions, causing potential injury to personnel and extensive damage to the facility.

    Boiler Maintenance Checklist For Daily Practices:

    Inspect the Waterside

    It is crucial to inspect the water components of the industrial boiler system. Industries regularly need to check for any mineral scale that might reduce the efficiency of the steam boiler. Any form of blockage within the pipes will impact the production levels. If it takes more energy for the boiler to push the hot water or steam, it is an indicator that the pipes are facing built up. Assess the tubes, furnace area, and gasket sealing surfaces. If the plants lack the tools to perform these inspections, ask for professional help who is well-equipped for these types of exams.

    Inspect the Fireside and Burners

    Process plant managers also need to inspect the fireside and burners. It is important to look for any signs that might reduce the efficiency of the industrial boiler. It is also necessary to check for any leakage that would call for repair. If there is a lot of soot, it indicates a larger problem. It is also vital to check the dampers, electrodes, novels, hoses, scanners, and diffusers. Plants are looking for any signs of blockage or erosion. If there are worn or damaged parts, it needs to be replaced immediately to optimize the efficiency of the boiler’s combustion processes.

    Analyzing the Controls

    It is also crucial to regularly analyze the controls. Proper water levels are critical for operational safety and optimal efficiency. Therefore, it is prudent to look for any signs of cracks or erosion. Plant personnel also need to inspect the equipment, taking a closer look at their output. In that way, it can be determined if something goes wrong. If one of the controls is not reading accurately, it indicates a deeper issue in the industrial boiler system. In such cases, the assistance of a reliable boiler manufacturer is advisable.

    Visual Inspection for Cracks

    Additionally, it is crucial to take a step back and do a visual inspection, checking for any signs of cracks. Even minor cracks can greatly reduce the efficiency of the industrial boiler, adding to the stress on the inner components. As a result, it can increase utility bills. If there are cracks, likely, metal parts are also damaged. While seeking professional boiler manufacturers to repair, make sure they utilize a high-quality patching compound. That way, these cracks do not return.

    Ensure Routine Boiler Maintenance

    Daily inspections are important when considering the return on investment for the industrial boiler. Even though it may seem that the boiler is operating properly, routine maintenance helps operators in identifying any signs of leaks, breaks, or other types of damage at the initial stage. If a loose screw is reducing performance output, the boiler system loses its efficiency. Such minor details are usually neglected but can significantly impact the boiler performance.

    Furthermore, boiler maintenance can reduce utility expenses by maintaining production levels. If the industrial boiler requires more energy for generating the same target output, it indicates that the system is operating at a loss. Along with daily inspections, monthly boiler maintenance from a reliable boiler manufacturer ensures that the internal and external systems of the boiler are operating seamlessly. Consider the frequency, duration, and target output levels of the industrial boiler while developing a maintenance schedule.

    Conclusion:

    Rakhoh Boilers is one of the trusted boiler manufacturers in Pune since 1983. With 39+ years of experience and expertise in thermal solutions, we deliver highly efficient and reliable industrial steam boilers, waste heat recovery systems, thermic fluid heaters, and boiler accessories to over 20 process industries in 27 countries worldwide. We provide excellent boiler services to boost the efficiency and productivity of the boilers.

    Visit www.rakhoh.com for more details on our products and services

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