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National Association of Infrared Specialists
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16192 Coastal Highway, Lewes, Delaware 19958
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NAIS Specialty Applications Standards of Practice (SpecSOP)
This standard sets the requirements for infrared surveys of specialty equipment including photovoltaic (solar)
systems, process equipment, buried infrastructure and aerial (drone) surveys.
Section 1: Purpose, Scope and Alignment
1.1 Purpose. To set minimum requirements for infrared surveys of photovoltaic systems, process
equipment and refractory, buried pipe and radiant heating, and aerial (drone) surveys.
1.2 Alignment with NAIS Core Standards. This standard is an addendum to the NAIS Core Standards
of Practice (CoreSOP) and the NAIS Code of Ethics. Everything in the CoreSOP applies unless this standard says
otherwise.
Section 2: Photovoltaic (Solar) Systems
Reference: IEC TS 62446-3.
- The survey shall be done with the array operating and with enough sunlight to produce a clear pattern. The
thermographer shall record irradiance with a calibrated meter and follow the minimum in the referenced standard
(typically 600 W/m squared or more).
- The sky should be mostly clear with low wind, and the survey should avoid hours when shadows or reflections
fall on the array.
- Modules shall be imaged at an angle that avoids reflecting the sun or sky into the imager.
- The report shall record string or module identifiers for every anomaly and describe the pattern (single hot
cell, hot substring, hot junction box, whole-module heating) rather than name a cause as certain.
- The thermographer shall not open combiners or disconnect strings. Electrical safety follows ElecSOP Section
2.
Section 3: Process Equipment, Furnaces and Refractory
- This work shall be done only by a thermographer with experience of the process and with the operator's written
access procedure.
- High-temperature surfaces shall be read with an imager and range suited to the temperature, and emissivity
shall be set from the actual material and temperature.
- Steam, smoke and combustion gases absorb and emit infrared. They shall be avoided or recorded as a limitation.
- Refractory and insulation findings shall be compared with design surface temperatures and an earlier baseline,
where one exists.
Section 4: Buried Pipe, Steam Lines and Radiant Heating
- The survey shall be done when the temperature difference between the system and the ground or floor is large
enough to show, and the thermographer shall record how that was judged.
- A thermogram shows only surface effects. The report shall say that depth and cause are inferred, and shall
recommend confirmation by excavation, flow tests or a locating method before repair.
- Radiant floor and wall heating surveys should be done while the system is running at steady state.
Section 5: Aerial (Drone) Surveys
- The pilot shall hold the license or authorization that the law requires (in the United States, FAA Part 107,
and the equivalent elsewhere) and comply with airspace, privacy and property rules.
- The thermographer shall calculate the ground sample distance for the planned height and imager. The pixel size
on the surface shall be small enough to resolve the anomalies sought; if it is not, fly lower or record the limit.
- Wind, gusts and temperature shall be within the limits of both the aircraft and the imager, and conditions
at flight height shall be recorded.
- Where aerial imagery is used for quantitative findings, the reading shall be checked against a ground measurement
on at least one comparable target.
- The report shall record the aircraft, imager, height, speed and flight date.
Section 6: Reporting and Limitations
Every report shall meet CoreSOP Section 7 and carry the CoreSOP limitations statement, adapted to the application.
A new application added to this standard shall state its scope, safety rules, required conditions, procedure and
verification method.
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