Novelty Structures is an experienced custom
industrial boiler fabrication and contract manufacturing partner.
Table of Contents
1. Parts of Boilers
The construction of a boiler plant requires a diverse range of raw materials, components, and auxiliary equipment. These materials are broadly classified into three main categories, each contributing approximately 30 to 40% to the overall cost of the boiler plant. The categories are outlined in below table.
- Boiler Steels: These are materials primarily used for the construction of the boiler itself.
- Structural Steels: Employed for the structural components supporting the boiler.
- Bought-Outs (BOs): Components purchased externally, contributing significantly to the overall boiler construction.
Photo 1: Boiler Steel Plates
Boiler quality plates are crucial components in boilers, tasked with withstanding high pressure and temperature conditions.
Key Requirements for Boiler Quality Plates:
- Consistency and Uniformity:
- Properties must be consistent and uniform across the length, width, and thickness of the plate.
- Consistency ensures structural integrity and reliable performance under varying conditions.
- High Purity of Steel:
- Boiler quality plates require a high degree of steel purity.
- The high steel purity minimizes impurities, enhancing the overall strength and durability of the plates.
- No Inclusions or Air Pockets:
- Strict adherence to quality standards requires the absence of inclusions or air pockets in the plates.
Characteristics of Boiler Quality Plates:
- Low Carbon Content:
- Low carbon content is essential for good weldability.
- It also facilitates efficient welding processes during the fabrication of boiler components.
- High Tensile Strength:
- Boiler quality plates exhibit high tensile strength.
- This characteristic is critical for limiting drum thicknesses and ensuring structural stability under high-pressure conditions.
- High Thicknesses:
- Boiler quality plates are designed to be effective in higher thicknesses.
- Suitable for applications where robust and thick plates are required to withstand extreme conditions.
Categories of Boiler Quality Plates Based on Tensile Strength:
- Carbon Steel:
- Subdivided into low, medium, and high carbon categories.
- Offers a range of tensile strengths suitable for diverse boiler applications.
- Low-Alloy Steel:
- Incorporates alloying elements to enhance specific properties.
- Provides improved performance compared to standard carbon steel.
- High-Alloy Steel:
- Contains higher proportions of alloying elements.
- Offers the highest tensile strength among the three categories, catering to specialized requirements.
Tubes and pipes play distinct roles, each subjected to different challenges based on their location within the boiler system. The key considerations for boiler tubes are;
- Seamless Tubes:
- Produced by piercing a red-hot billet.
- ERW Tubes:
- Produced by folding and welding steel strip.
- Preferred for lower thicknesses, providing benefits like smoother inside surfaces, concentric bores, and cost efficiency.
- Hot-Finished and Cold-Drawn Seamless Tubes (HFS and CDS):
- HFS tubes have higher pressure drop and tolerance levels.
- CDS tubes, produced by reheating and rerolling HFS tubes, offer closer tolerance.
- Selection depends on the boiler section and specific duties.
- Tube Materials and Comparison:
- Carbon, alloy, and Stainless Steel (ss) tubes are used.
- Selection of Tube Materials:
- Temperature limits and material strength at operating temperatures govern selection.
- A good boiler design optimizes the use of low-carbon steels and minimizes the use of expensive materials like Stainless Steel.
- Tube Ordering:
- Tubes are received in bundles, marked with specifications, and color-coded for identification.
- Punching tubes is discouraged to avoid outer layer damage.
- Tubes can be ordered in exact lengths, and hydraulic testing (HT) is an ideal QA measure.
Photo 2: Boiler Tubes
Structural Steel is used for the Non-Pressure Parts (NPPs) of boilers, which include essential components like flues, ducts, casing, hoppers, penthouse, and bunkers. Unlike Pressure Part (PP) steels, the specifications for structural steels are outlined in the codes, certain considerations must be addressed, particularly as structures become larger.
Key Considerations:
- No stringent requirements similar to PP steels, but challenges arise with larger sections becoming excessively heavy.
- Fabricated sections from plates become competitive when welding and handling costs are lower, despite limited suppliers, protracted deliveries, and higher specific costs.
Basic Requirements of Structural Steel:
- Good weldability and strength are fundamental requirements.
- Cold structure members need adequate notch toughness, especially in very cold climates.
- Components for hot structures, like buckstays and sling rods, are often designed for temperatures <400°C and do not require specific high-temperature properties like those for Pressure Parts (PPs).
Structural Steel Codes:
- Below Table 2 provides an overview of structural steels required in boilers, detailing various types used in NPPs.
- Table 3 offers the structural material codes for American standards, along with their nearest BS and DIN equivalents.
- Specifications within codes cover basic material grades and their properties, while individual standards detail dimensions and other related mechanical aspects of each rolled section.
Table 2 Structural Steels in Boilers
Table 3: Boiler Structural Steel Grades
3. Boiler Steel Grades
4. Challanges in Boiler Manufacturing
| Challange | Description | Impact |
|---|---|---|
| Material Selection | Choosing materials that withstand high pressure, heat, and corrosion is crucial but difficult. | Poor-quality materials can cause failures. |
| Welding Precision | Welds must be flawless to avoid leaks and ensure strength under pressure. | Defective welds can lead to structural issues. |
| Corrosion Resistance | Boilers face harsh environments that accelerate corrosion. | Corrosion shortens lifespan and raises maintenance costs. |
| Complex Designs | Custom boilers must meet unique needs while remaining efficient. | Errors in design can reduce performance. |
| Strict Standards | Compliance with safety and industry codes requires rigorous testing and documentation. | Non-compliance can lead to legal or operational issues. |
| Testing and Quality Checks | Detecting flaws in large systems requires specialized tools and expertise. | Undetected defects can cause operational failures. |
| Thermal Stress | Boilers expand and contract with temperature changes. | Poor stress management can cause cracks or warping. |
| Handling Large Components | Moving and assembling heavy parts without damage is challenging. | Mishandling can lead to deformation or delays. |
| Skilled Labor Shortages | Finding experienced welders and engineers is difficult. | Delays and lower quality due to lack of expertise. |
| Cost and Time Pressures | Tight budgets and deadlines can force compromises in quality. | Cutting corners risks safety and reliability. |
5. Applications of Boilers
| Industry | Application | Details |
|---|---|---|
| Power Plants | Steam generation to drive turbines for electricity production. | High-pressure, high-temperature boilers. |
| Chemical & Petrochemical | Process heating, steam generation, and driving turbines. | Used in distillation, chemical reactions. |
| Food & Beverage | Sterilization, pasteurization, cooking, and cleaning. | Steam is essential for cooking and cleaning. |
| Pharmaceutical | Sterilization and heating in manufacturing processes. | Boilers provide steam for sterilization. |
| Paper & Pulp | Steam for cooking, drying, and mechanical operations. | Used in pulp processing and paper production. |
| Textile | Steam for dyeing, pressing, and finishing treatments. | Steam powers textile machines. |
| District Heating | Centralized heating for residential and commercial buildings. | Boilers supply heat and hot water to communities. |
| Oil & Gas | Steam generation for refining and gas processing. | Used for recovery and processing. |
| Steel & Metallurgy | Steam for smelting, shaping, and treating metals. | Boilers heat and power metal production processes. |
| Large Buildings & Plants | Heating systems in industrial plants, factories, and office buildings. | Boilers provide heat and hot water. |
| Waste-to-Energy | Converting waste materials to energy using steam. | Boilers burn waste to generate energy. |
| HVAC & Cooling Systems | Provide steam or hot water for large buildings and industrial processes. | Boilers are essential for maintaining temperature control. |
FAQ
Industrial boiler fabrication involves the design, manufacturing, and assembly of boilers that are used in industrial processes. It includes the selection of appropriate materials, welding, assembly of various components, and ensuring that the final product meets the necessary standards for pressure, temperature, and efficiency.
The main types of industrial boilers are:
- Fire Tube Boilers: Hot gases pass through tubes surrounded by water. Common in smaller applications.
- Water Tube Boilers: Water flows through tubes heated by the fire, used for high-pressure applications.
- Fluidized Bed Boilers: Used for burning various fuels efficiently and are typically found in power generation plants.
- Waste Heat Boilers: Designed to recover energy from exhaust gases.
Regular maintenance of industrial boilers involves:
- Inspection: Checking for signs of wear and tear, corrosion, and leaks.
- Cleaning: Removing scale and soot buildup that can affect efficiency.
- Pressure Testing: Ensuring the boiler operates within the specified pressure limits.
- Replacement of Parts: Replacing worn-out components such as valves, tubes, and seals.
- Monitoring: Continuously monitoring key parameters like temperature, pressure, and efficiency.
Refractory materials are used to line the interior of a boiler’s combustion chamber and other areas exposed to high temperatures. They protect the boiler from heat damage, prevent heat loss, and enhance the overall thermal efficiency of the system.
The lifespan of an industrial boiler can vary based on factors such as the type of boiler, the materials used, and how well it is maintained. Generally, industrial boilers can last between 20 to 40 years with proper care, though certain components may require replacement during that time to ensure continued performance.
Yes, industrial boilers can be customized to meet the specific needs of different industries. Customizations may include size, fuel type, pressure, temperature, and additional features such as economizers or superheaters to enhance efficiency.
Safety is a major concern during boiler fabrication and operation. Key safety considerations include:
- Pressure Testing: Boilers must undergo rigorous pressure tests to ensure they can safely handle the required operating pressures.
- Welding and Structural Integrity: All welds must be inspected to ensure there are no defects that could lead to boiler failure.
- Code Compliance: Boilers must adhere to safety codes such as ASME (American Society of Mechanical Engineers) or EN (European Standards) for design, fabrication, and installation.
- Fire and Explosion Risk: Boilers should be designed to prevent the risk of explosion or fire by ensuring proper venting, combustion control, and flame supervision.
The time required to fabricate an industrial boiler can vary depending on its complexity, size, and customization. On average, fabrication can take anywhere from several weeks to several months. This includes design, material procurement, welding, assembly, pressure testing, and commissioning.
