Boiler Tube Failure Analysis and Testing
Boiler Tube Analysis and Testing: A Boiler Tube Failure is a Symptom of Problems.
Boilers of all types and sizes continue to experience boiler tube failures. When boiler tube root cause and failure mechanisms are not clearly identified, then boiler tube analysis and testing may be needed. Repairs
can be incomplete or worse dangerous conditions may still exist after the repair. AIS Metallurgical Testing has years of experience with boiler tube failures including economiser tube failures, overheated steam drums and water drums (mud drums) as well as boiler headers, superheater tubes and economizer tubes.
Failure of boiler tubes are a significant cause of industrial and utility boiler forced outages in all types of fossil-fired boilers. Boiler tube analysis and testing as well as for heat exchangers like steam turbine condensers can reduce or eliminate reoccurrence. At AIS we believe it is extremely 
important to find the root cause and failure mechanisms using experience and comprehensive assessment method(s).
We will encourage you
to investigate the aspects of the boiler operation leading up to the failure to fully understand the cause(s).
Tube Analysis for Root Cause or Failure Mechanism
The first step in boiler tube analysis by AIS is to perform a visual inspection of the tube. We will communicate with you our preliminary observations and make suggestions on how to proceed in the boiler tube analysis or heat exchanger tube analysis that fits your budget. Root cause analysis or determination of failure mechanism typically will require metallurgical analysis such as tube material composition and its' microstructure. Since, a fair amount of boiler tubes have deposits, then analysis of fireside and waterside tube deposits (chemical composition and morphology of deposits) may need to be included. There may be at least two failure mechanisms 'at play' in a tube failure and sometimes three-failure mechanisms or more. So, send your boiler tube or heat exchanger tube today for a free visual inspection today!
Watersides
- Tube Roll Life and Over-Crushing Tube
- Deposit Analysis (Scale)
- DNB (Departure from Nucleated Boiling)
- Tube Corrosion Loss
- Deposit Weight Density
- Low Water Condition in Boiler
- Steam or Water Drum Analysis
Firesides
- Corrosion (Flue Gas - Biomass, Refuse...)
- Erosion from Flue Gas Stream (Biomass, Refuse, Coal Ash) or Steam
- Accumulated Exposure to Elevated Temperatures
- Component Failure: Clips, Brackets, Supports, Hangers, Seals, Straps and Membranes
- Overheating
- DNB (Departure from Nucleated Boiling)
- Economiser Erosion and Flue Gas Corrosion
Cold-side
- Mechanical Component Failure
- Strapping
- Overstressing
Condenser Tube
- Corrosion
- Tube Roll Life
- Fretting
Some Boiler Tube Analysis Case Files: Boilers burning - Bio-Mass, Gas Fired, and Oil-Fired
Evaluating the Watersides failures or
Independent Power Producer – Small Utility Station – Biomass with Light Refuse Supplement
Superheater Tube Failure: High-temperature Oxidation: The unit had an unscheduled shutdown with penalties. The superheater tube experienced rupture when the tube wall thinned from localized high-temperature oxidation where the outside boiler tube surface temperature relative to the oxidation limit of the tube material was elevated. In this case the fireside ash corrosion characteristics is dependent on temperature including fuel and boiler design. Damage occurs when particular ash constituents which are corrosive when molten on the superheater tube surfaces.
Institution – High-Temperature Hot Water Fire Tube Boiler - Rear Tube Sheet – Fuel Oil
Low water condition occurred in the fire tube scotch marine boiler requiring a retube. The rear tube sheet appeared visually acceptable and was initially considered safe. However, the rear tube sheet was found to have experience a reduction in strength and microstructure changes consistent with moderate to long term localized elevated temperatures in the ASME carbon steel that was specified when built decades ago.
Facility or Institution with a High-Temperature Hot -Water Tube Generator (Boiler): Fuel Oil and Gas Fired
The boiler had been experiencing unexpected costly shutdowns during the heating season. A macro examination was afforded of a tight bend (hair-pin) radius tubes that were failing. These tubes were failing from corrosion from the watersides. The corrosion pattern found were isolated pitting corrosion from the following sources when AIS assisted the heating plant staff and found the corrosion products (iron-oxides) originated from the heating loop off site including entrainment of atmospheric air when drained (poor lay-up) and under treated fresh domestic water for dissolved O2 (oxygen) and CO2 (carbon-dioxide).
Instructions on Shipping Your Tube to 'Get a Free Consult'
We know boilers, so naturally we understand the differences between a reheater tube or a waterwall tube as well as these boiler / generators -
- Refuse Burners
- Bio-Mass
- Fossil Fuel - Coal, Fuel Oil and Natural Gas
- Heat Recovery Generator
Is this important to you? We will let you be the judge of that!
Tube Analysis - What To Do Before Shipping Tube
First (Step One), before shipping or removing the boiler tube for analysis take a picture of the boiler tube or heat exchanger tube in the boiler and the tube sheet that the heat exchanger tube came from. (MAKE SURE THE TUBE IS NOT CLEANED - NEED TUBE 'AS IS CONDITION') When possible include a diagram of there the tube sample was located in the boiler or heat exchanger such as:
- Type of boiler and location in Boiler
- Heat Pass location and flow direction
- Elevation such as at the steam drum (how close)
- Type of tube: screen wall tube or furnace wall tube, boiler bank, generating bank, superheater (radiant, convection), economizer.
- Boiler pressure, temperature, steaming rate, operating hours
- Diagrams or drawing sheets showing location(s)
- Tube material (what it is supposed to be)
- Tube repair history
- Description of water treatment program
The above information is not always provided; however, when the information is given early in the tube analysis the boiler tube analysis results benefit.
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Steel Making Tutorial
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Preparing Shipping Tube and Shipping Instructions:
Boiler Tube Shipping for Analysis
Step Two: 'Dutchman' the boiler tube that is needed for analysis. the boiler tube length should normally be a length of 3-feet (1-meter) but not less than 1- 1/2-foot in length. This is also true for a heat exchanger tube or condenser tube. Tap the ends immediately and wrap tube carefully
Step Three: Call AIS Forensic Testing Laboratory at 800-249-0959 and have our 'Boiler Tube Shipping Container' shipped to you! Our shipping container will have a pre-paid shipping label inside for easy shipment of your boiler tube.
Step Fourth: Take paper and stuff tightly at one-end for a depth of 1/2-foot. While at the end cover the end with corrugated box scrap and make sure it is large enough to fold over the sides. Now, tape generously the corrugated end to the PVC so no cardboard is exposed. This step provides reinforcement.
Step Five: Drop the Boiler Tube Shipping Container off to your nearest shipper.
Ship Boiler Tube to:
AIS Forensic Testing Laboratory, Inc.
212 Elmwood Ave Ext.
Gloversville, NY 12078
Inside the shipment leave a note who to telephone, an email address and a mailing address for correspondence.
http://www.boilertubeanalysis.com / http://www.boilertubetesting.com