Waterwall Chordal Thermocouples
Are you having boiler tube scaling issues or tube failures occurring? Are your boiler’s waterwalls free from obstruction to allow for optimum circulation? Consider installing chordal thermocouples to monitor the tube temperatures.
Monitoring Waterwall Temperatures with Chordal Thermocouples
Waterwall tube metal temperatures peak on the fireside crown of the tube. Under clean conditions, this mean wall temperature typically remains less than 75°F above saturation, with supercritical boilers operating within a similar 50-75°F differential. However, when circulation is obstructed or water-side deposits accumulate, metal temperatures can rapidly escalate to the point of catastrophic overheating.
Predicting Distress & Preventing Failures
Chordal thermocouples are a highly effective, proactive tool for monitoring heat flow through the tube wall and predicting metal distress before a failure occurs. To establish an accurate trend of water-side scale accumulation, we recommend the following best practices:
Consistent Weekly Monitoring: Record the mean wall temperature readings on a strict weekly basis—especially if a history of water-side deposits previously required an acid cleaning.
Controlled Baseline Conditions: Always record temperatures at the same high operational load and with the exact same burners in service to ensure data accuracy.
Proactive Tube Sampling: If the thermocouple data reveals a gradual, steady climb in temperature, an adjacent tube sample should be removed for internal deposit analysis.
Overheating Tube Metal Temperatures by 50°F can Reduce Tube Life by 86.3 Years!!!
Common causes of boiler tube failures:
- Water-plugging of superheater tubes on startup
- Stratified furnace gases with high temperature lanes that overheat specific tubes
- Water-side deposits become more of an issue with cycling due to the shaking up of the pre-boiler cycle during startups and shutdowns.
Custom Fabrication by STORM
To help you maximize boiler reliability and eliminate surprise waterwall blowouts, STORM® custom-designs and manufactures these specialized chordal thermocouple tube sections to seamlessly integrate into your furnace walls.