Boiler Inspection

SIGMA NDT provides very specialized inspections for Water Tube and Fire Tube boilers of all sizes. For Generating Banks in Drum-to-Drum Boilers, we provide full-length tube inspections that can detect and quantify flaws in the straight and bend sections of the Boiler Tubing. We can conduct this test from the Mud Drum (w/ CL to CL < 25’) or Steam Drum. For the inspection of Boiler Generating Banks, we use the Multichannel Remote Field Electromagnetic Technique (RFET) System.For the Furnace or Waterwall tubes in larger Industrial & Utility Boilers, we provide Boiler Waterwall Scanning services. This service detects ID or OD flaws on the hot-side half of the tube.

To gain access to these areas, we can work from hard scaffolding or swing staging. In gas burning boilers, no surface preparation is needed for this service. The same is true for most oil burning units. If a boiler burns coal, many times a quality high-pressure water blast is all that is necessary. For the inspection of the waterwalls, we use the Tube Scanning system based on Low Frequency Electromagnetic Technique (LFET). Our LFET technology scans approx. 120 degrees of the tube circumference with a single pass of the LFET scanner. Any flaw indications (or areas that we cannot scan due to tube bends, welds, viewports, etc.) are proved-up using A-Scan Ultrasonics.SIGMA NDT also provides O.D. scanning services for the Super Heater and Reheater areas of boilers, and sometimes even the Economizers. This service also employs the LFET Tube Scanning System.For the inspection of Generating Banks found in Drum-to-Drum Boilers, there are three other methods, which are Spot Check UT, IRIS Ultrasonic Testing, and I.D. Laser Profiling (LOTUS). Traditional Spot Check UT is conducting from the O.D. (fireside) of the tubes, and is generally limited to areas that a person can access, or “put his hands on.” This gives very limited coverage and leaves a large percentage of surface area untested.

Advantages

Inspects straight sections and bends

300-400 Gen. Bank Tubes can be inspected using RFET in a single 10 hour shift.

2,000-3,000 linear feet can be scanned using LFET in a single 10 hour shift.

SIGMA NDT can field 50+ inspection crews at any given time.

SIGMA NDT comes with multiple scanner/probe sizes and back-up equipment so that there are no delays on our part.

Neither RFET nor LFET require extensive tube cleaning.

Can inspect tubing from 0.5” diameter and up.

Both SIGMA NDT RFET and LFET get more area coverage than the other respective techniques.

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