Industrial Boilers: A Guide to Inspection and Maintenance
Industrial boilers are critical pieces of equipment in various manufacturing industries. They generate steam or hot water for use in various industrial processes, making them an essential component of any manufacturing plant. As with any other mechanical equipment, industrial boilers require periodic inspection and maintenance to ensure they remain safe and efficient.
In this article, we will discuss the key steps involved in the inspection and maintenance of industrial boilers.
Step 1: Check Boiler Drawings and History Before starting any inspection or maintenance work, it is essential to review the boiler drawings and history. This includes verifying the materials used, the size of tubes, fire bricks, refractory, steam drum internals, and baffle plates. Additionally, reviewing the boiler’s history can provide valuable insights into past issues such as tube failures, overheating, and other forms of repairs or replacements.
Step 2: Carry out Joint Inspection and Entry Permit Before entering the boiler for inspection, it is crucial to carry out a joint inspection to ensure all safety measures are in place. This includes verifying the provision of blinds and ventilation, lighting, scaffolding, and obtaining an entry permit. Additionally, ensure a man watch is available for your safety.
Step 3: Preliminary External Inspection Conduct a preliminary external inspection for any external flue gas leaks, external damage to the boiler casing and structure, burner assembly, and fuel leaks.
Step 4: Gas Test Before Entry Before entering the boiler for internal inspection, conduct a gas test to check for adequate venting and ensure the boiler is free from any foul smell or toxic gas release. Additionally, verify there is adequate lighting and scaffolding for inspection and ensure a man standby is available for safety.
Step 5: Internal Inspection Start the preliminary visual inspection of the boiler’s internals, including the furnace or firebox, bank and superheater section, flue gas duct, steam, and mud drums, and economizer (if available). Pay particular attention to the boiler floor, bank tubes, burner assembly, burners, refractory walls and roof, flue gas duct, and stack.
Step 6: Tube Inspection Inspect the tubes, bends, significant overheating of target wall tubes, bulging, bowing, distortion, and scaling of tubes. Recommend tube external and internal cleaning for detailed inspection.
Industrial boilers are critical components in various manufacturing industries, making their periodic inspection and maintenance critical for optimal performance, safety, and efficiency. By following the steps outlined in this article, you can ensure your industrial boiler is in good condition and can continue to provide the necessary steam or hot water for your manufacturing process.
Industrial Boilers: Importance of Inspection and Cleaning
Industrial boilers are an integral part of many manufacturing and processing plants. These machines use heat and pressure to produce steam, which can then be used to power turbines and other equipment. However, like all machinery, industrial boilers require regular inspection and maintenance to ensure that they are operating safely and efficiently.
One crucial aspect of boiler maintenance is cleaning the tubes. Over time, these tubes can become coated with scale, rust, and other deposits that can decrease their efficiency and potentially cause damage to the boiler. To ensure that the tubes are adequately cleaned for inspection, a preliminary external inspection should be carried out for external flue gas leaks, external damage to the boiler casing, and structures, burner assembly, and fuel leaks.
If cleaning is deemed inadequate, further cleaning should be requested before carrying out a detailed inspection. During the inspection, the tube surfaces should be checked externally for any significant corrosion or mechanical damage, bulge, tube distortion, or bowing. Special attention should be paid to the target wall and roof tubes for possible flame impingement and tube surface bulge.
It is also crucial to conduct gas tests internally before entry to the boiler for inspection to ensure that the boiler has adequate venting and is free from any foul smell or toxic gas release while scales or deposits are disturbed. This will help prevent any accidents or health hazards during the inspection.
During the internal inspection, the tubes, bends, and significant overheating of target wall tubes, bulging, bowing/distortion, and scaling of tubes should be thoroughly checked. UT should be requested for the full length of tubes, including bends, and hardness should be measured at random locations most affected by the flame. These measures will help identify problem areas and predict any potential issues.
In addition to the tubes, the steam drum and internals should be inspected for cracks, corrosion, and other damages. The mud drum should also be inspected for corrosion, accumulated deposit, tube ends, and tube end thinning. The flue gas duct and stack should also be inspected for accumulated ash, clean and inspect for cracks, and damage to the refractory that may eventually result in flue gas leaks while in operation.
Regular inspection and maintenance of industrial boilers are essential to ensure they are operating safely and efficiently. Any potential issues should be identified and addressed promptly to prevent accidents and minimize downtime. With the right care and attention, industrial boilers can continue to provide reliable service for many years.
Firstly, a full inspection should be conducted to identify any cleaning, repair, or re-tubing needs. Any recommendations and related repairs should be followed up according to applicable standards such as ASME and API.
After completion of repairs and cleaning, a final inspection should be carried out to assess the boiler’s condition for operation during the next EIS period. If the inspection reveals that the heater does not comply with inspection findings for further service, then an FFS assessment should be done. In such a case, the heater can go through minimally the EIS period, and a request for change of EIS schedule should be made. A partial or full re-tubing of the heater should be requested for the next time with spare tubes on hand for replacement.
The boiler shall be pressure tested at its test pressure (Design pressure x 1.5) after inspection and repairs. The nameplate and SIS should be referred to for the test pressure. Any tube leaks at hydrostatic test should be renewed partially or in full as deemed and retested.
The applicable standards and codes to be followed are SAEP-20, SAES-W-010, ASME SEC VIII D1, API STD 530, and API STD 510. Any repair to the heater should be hydrostatically tested per SAES-A-004 and ASME SEC VIII D1. The operation engineer of the unit should provide the test procedure, or waivers should be submitted per SAEP-20 in advance. The test or waiver documents shall be filed for reference.
After commissioning the boiler, the safety valves should be floated prior to full operation, and an in-place test procedure should be followed strictly in performing the test.