Sample Program

This section incorporates the above recommendations and could serve as the basis for a program using infrared thermography as part of a predictive maintenance program.

1.0 INTRODUCTION

1.1 This program is for the administration and conduct of an infrared inspection program of electrical and mechanical equipment. The purpose of this program is to identify

equipment that requires maintenance and to improve its reliability through the use of infrared thermography (IR).

1.2 This document contains the recommended scope, frequency, and corrective action criteria for routine and unscheduled infrared surveys.

1.3 Requests for changes to this program and questions relative to it shall be directed to the administrator of the IR program.

2.0 DEFINITIONS

2.1 Infrared – Electromagnetic radiation having wavelengths that are greater than those of visible light, but shorter than microwaves. As it applies to IR thermography, the wavelengths are between 3 to 15 micrometers.

2.2 Infrared Survey – A comprehensive examination of components and equipment with an infrared imaging system.

2.3 Emissivity – The ratio of radiance from a surface to the radiance at the same wavelength from a perfect blackbody at the same temperature. Functionally, this is the radiation efficiency of a surface in the infrared spectrum.

2.4 Radiosity – Thermal energy of a surface as seen by the infrared detector.

2.5 Thermogram – A recorded, displayed, or hard-copy image of the output of an infrared imaging system.

2.6 Isotherm – A thermal contour on a thermogram where all of the spots along it are at the same apparent temperature.

2.7 Infrared thermographer – An individual who is trained and qualified to operate infrared imaging equipment and to interpret the images.

3.0 SCOPE

3.1 The requirements of this procedure shall apply to all safety-related components. It shall also be applicable to non-safety-related equipment where financial benefit might be achieved by monitoring (that is, increased plant availability, decreased maintenance costs, and so on).

• Interval selection

• Determining component acceptability 4.0 RESPONSIBILITIES

4.1 Administrator of IR – It is the administrator’s responsibility to oversee the program. This includes making changes to the procedure. All surveys, whether they are scheduled or conducted on an emergency basis, shall be approved by the administrator or his/her designee. The administrator shall be responsible for budgeting, planning, and interfacing with outside organizations.

4.2 Infrared Thermographer – The infrared thermographer is the only person trained and qualified to operate the infrared imaging equipment. He/she is responsible for conducting the surveys, interpreting the images, writing the reports, and acting as a technical

resource to other plant departments. The infrared thermographer is responsible for the maintenance and calibration of the infrared imaging equipment.

4.3 Cognizant Engineer – At the request of the infrared thermographer, a discipline-cognizant engineer will provide assistance in diagnosing a problem. The cognizant engineer will also suggest corrective action and provide coordination with other plant disciplines.

4.4 Root Cause – Determination of root cause and the subsequent applicable action level shall be the responsibility of plant management. When necessary, the infrared

thermographer shall request assistance from a cognizant systems or maintenance engineer in determining the root cause or the recommended corrective action.

5.0 PRECAUTIONS

5.1 Many of the components that are being inspected represent potential plant trip hazards;

exercise extreme care.

5.2 All safe work practices as outlined in the plant safety manual, shall be followed. These practices include exhibiting caution near energized electrical equipment, rotating equipment, and hot pipes. All surveys shall be conducted from a safe stable location.

5.3 Infrared surveys within the Radiological Controls Area shall be conducted within the guidelines of the Health Physics Department. In areas of potential contamination, the infrared thermographer shall be responsible for covering the equipment with plastic as directed by Health Physics.

5.4 When practical, surveys in areas of airborne contamination should be avoided. When this is not possible, a thin piece of polyethylene or plastic can be placed over the lens. If this is done, the transmittance of the covering must be taken into account.

6.0 PREREQUISITES

6.1 Personnel – The infrared thermographer and one craft person constitute the minimum personnel necessary to conduct a survey when the operating or opening of equipment is necessary.

6.2 Approvals – The required approvals to conduct a survey shall be coordinated with the IR administrator. The control room should be notified both prior to the start of the survey and at its end. If requested, the infrared thermographer will inform the control room prior to opening equipment that presents a possible plant trip hazard.

6.3 Emergencies – In cases where requests for surveys are done on an emergency basis, the infrared thermographer shall fulfill the duties of the IR administrator and provide the necessary coordination.

7.0 CONDUCT OF THE SURVEY

7.1 The equipment survey matrix shall identify the equipment to be surveyed and the frequency of the survey.

7.2 The sequence of the survey is not important unless specifically stated in the procedure or requested by either Maintenance or Operations. All equipment on the matrix must be surveyed unless it is not in operation or conditions dictate otherwise. The infrared thermographer shall note any exceptions in the inspection report.

7.3 Standard practice is to videotape all surveys and to include an audio track for verbal identification and discussion.

7.4 The thermal images must be of sufficient resolution to identify the components and any problem areas.

7.5 When problems are identified, the thermographer shall reposition the imager and obtain more than one view. This is done to eliminate the possibility of apparent problems being caused by reflections from hot objects. The hard-copy images should be obtained from the position that provides the best image.

7.6 All problems are to be photographed in the visible as well as in the infrared. This is to allow proper and easy identification of the problem areas, which will facilitate

maintenance activities.

7.7 The problems shall be customarily reported as a temperature rise. This rise can be calculated from ambient, thermal baseline data, or made by comparison in the cases where similar equipment exists.

7.8 When absolute temperatures are requested or required, the infrared thermographer shall determine and use the target's effective emissivity to assure accuracy. A standard table of effective emissivities will be developed by measurement and will be maintained by the infrared thermographer.

7.9 Important information relating to test conditions, such as load, flow, and pressure shall be noted by the thermographer if it is available. This information will be used in component trend analysis.

7.10 The components shall be inspected with the imager aimed along a line normal (perpendicular) to the target surface whenever possible, to minimize the potential for

7.11 During the infrared inspection, the components must also be inspected visually and any discolorations, questionable noise, or smell should be reported.

7.12 In cases where precise measurements must be obtained, the instrument background radiation effects must be taken into account. Instrument background temperature can be determined by placing a good diffuse reflector (such as a piece of aluminum foil that has been crumpled and re-flattened) in ambient air and measuring its apparent temperature with the imager’s emissivity set to 1.0.

7.13 Where external optics, such as telescopic and wide-angle lenses are used, the

transmittance of the optics must be taken into account. The information that corrects the effects of these devices is supplied by the manufacturer and is entered directly into the imager software.

7.14 When measurements are being made on targets, the size of the target and the distance must be known. The IFOVmeas (Instantaneous Field of View for measurement) of the instrument must fit comfortably within the required target spot at the measurement distance. If these criteria are not satisfied, the instrument must be moved closer to the target and/or a higher magnification lens must be used. (See section 3.3.4 for a more detailed discussion of this subject).

7.15 The survey should be done with the imager scanned at a speed that does not cause blurring of the image so that acceptable thermograms can be obtained from the videotape on playback.

7.16 If requested or desired, a second (backup) measure of temperature can be obtained through the use of contact thermocouples or spot radiometers. (Care should be used in evaluating the results of measurements that are not calibrated.)

7.17 In general, equipment shall be surveyed when in a normal operational state. In cases where equipment is not energized or running normally, the thermographer shall note it in the IR inspection report.

7.18 Equipment such as batteries shall be surveyed during both normal operation and during discharge tests.

7.19 Requests for equipment operation for the sole purpose of an infrared inspection shall be coordinated with operations by the IR administrator. In most cases, this should be avoided.

7.20 All infrared inspections, whether done by on-site personnel or outside contractors, will be performed under the guidance and procedures listed in this program. Special tests outside of the normal inspection shall be reviewed and approved in advance by the IR

administrator.

8.0 ACCEPTANCE CRITERIA

8.1 Subsequent to an initial thermal baseline, the following action levels are to be used to classify each problem:

Advisory (Level 1) 1°F to 15°F rise Intermediate (Level 2) 16°F to 50°F rise

Serious (Level 3) 51°F to 100°F rise

Critical (Level 4) in excess of 100°F rise

8.2 When indications on components fall into levels 2, 3, 4, section 9 of the program shall be followed for reporting.

8.3 To determine acceptability of the inspection, the results and final report shall be compared against the criteria set forth in this program.

9.0 REPORTING REQUIREMENTS

9.1 Every scheduled and unscheduled infrared inspection shall be documented and reported in accordance with the requirements of this section (see Figure 6-1).

9.2 At a minimum, the report shall contain the following:

• Summary of inspection and findings

• Equipment list

• Data sheets with IR and visible photographs of anomalies

• Root cause analysis and corrective action

• Comments

9.3 The report shall be issued to the IR administrator within five working days of the completion of the survey.

9.4 A verbal report shall always be given to the on-site IR administrator upon completion of the survey.

9.5 The reporting of problems that fall within the four acceptance action levels are as follows:

Advisory (Level 1) Normal cycle of corrective maintenance.

Intermediate (Level 2) High priority during an unscheduled shutdown.

Serious (Level 3) Alert Operations—potential failure. Correct ASAP.

Critical (Level 4) Alert Operations, Management. Remove from service ASAP.

9.6 Items classified as serious are to be immediately reported to the IR administrator who will advise Maintenance and Operations.

9.7 Items classified as critical are to be immediately reported to Operations, Maintenance,

10.0 QUALIFICATION OF PERSONNEL

10.1 The infrared thermographer shall be qualified by examination and certified by the plant to conduct the survey.

10.2 The qualifying examination and training shall meet the guidelines of ASNT SNT-TC-1A (current edition).

10.3 In addition to the ASNT qualifications, the thermographer shall be knowledgeable in the following areas:

• Equipment-specific operation

• Infrared theory

• Heat transfer modes

• Safety practices

10.4 Certification of the thermographer shall be made through a written and a practical examination.

10.5 The plant Training Department shall administer the initial and re-qualification training.

11.0 SCHEDULING

11.1 The IR administrator is responsible for scheduling all routine infrared inspections.

11.2 The Equipment Matrix (Program, section 12.0) lists the frequency of inspection for each component.

11.3 Inspections on an emergency basis or for a special test shall be scheduled and coordinated by the IR administrator.

12.0 EQUIPMENT MATRIX 12.1 Component Selection Criteria

12.1.1 The components that are to be included in the thermographic analysis program should be selected based on the perceived or documented benefit of thermography on the type of equipment and the following criteria categories:

A. Critical: Critical equipment shall be defined as:

• Equipment whose function is necessary and must be available at all times.

• Equipment upon which thermography has been used to deviate from a specific vendor-recommended preventive maintenance activity.

• Equipment necessary to maintain full-power generating capabilities (that is, non-redundant).

B. Vital: Vital equipment shall be defined as those components whose function is necessary but that, through redundant design, do not have to be available at all times.

C. Vendor Recommended: Vendor-recommended equipment whose manufacturer or vendor recommends the periodic monitoring of the equipment with infrared

thermography.

D. Non-Vital: Non-Vital equipment shall be defined as:

• Equipment whose replacement cost versus periodic monitoring cost does not differ greatly and does not fall into category A or B above.

• Components that are used very infrequently and do not fall into category A or B.

12.1.2 The IR administrator shall maintain a listing of all of the components in the

thermographic analysis program, the category to which they belong, and their monitoring interval.

12.1.3 Equipment in category D that has a failure history relating to thermography might be included in the program in order to determine root cause, or to prevent failure recurrences or significant inconveniences. Otherwise, equipment in category D should be omitted from the program.

12.1.4 The above recommended component selection criteria should be applied predominantly to electrical equipment such as:

• Motor control centers

• Load centers

• Transformers

• Switchgear

• Battery chargers

• Switchyard equipment

• Large motor termination

12.1.5 The above criteria can also be applied to:

• Pumps/motors

• Steam traps

• Valves

12.2 Performance Intervals

12.2.1 The selection of performance intervals should be based upon several factors, such as:

• The impact of the component on plant operation and personnel safety if an unexpected failure were to occur.

• The speed at which a component fault manifests itself into a stage of degradation, which affects the component’s operability.

• Vendor/manufacturers’ recommendations.

12.2.2 When considering the vendor’s recommended frequency for thermography, the application of the equipment should be taken into consideration (that is, the run time experienced by the equipment in this installation versus what the vendor expects for typical run times). Also, if the component falls into categories A or B of 12.1.1, then the most limiting interval (between the vendor-recommended interval and the recommended interval in section 12.2.3 of the program) shall be used for the monitoring of the

equipment.

12.2.3 The following recommended intervals for the given categories should be used:

A. Critical Equipment

• Monitor quarterly for those components that are operated continuously or are op-tested at least quarterly.

• Monitor semi-annually for those components that are operated continuously or are run-tested at least semi-annually.

• At start-up, monitor when the component is placed on-line, is at a stabilized temperature, and has not been monitored for at least one monitoring interval.

• Equipment less than 240 V does not require periodic monitoring.

B. Vital Equipment

• Monitor equipment greater than 480 V quarterly.

• Monitor equipment greater than 240 V but less than 480 V semi-annually.

• Equipment less than 240 V does not require periodic monitoring.

12.2.4 Changes to monitoring intervals should be reviewed carefully prior to making changes in order to ensure that maximum component availability and program efficiency is

provided.

12.2.5 At a minimum, documentation for interval changes shall be maintained, by the IR administrator.

12.2.6 Components need not be operated for the sole purpose of collecting thermography data.

13.0 SUGGESTED PROGRAM REFERENCES

13.1 Infrared Thermography Guide (Revision 3), (formerly NP-6973) 13.2 Plant Administrative Procedures Manual

13.3 Plant Safety Manual 13.4 Plant Training Manual

13.5 Plant Quality Assurance Procedures Manual 13.6 Plant Systems Training Manual

13.7 Infrared Imager Instruction Manual

13.8 Plant Predictive Maintenance, INPO Good Practice 89-009.

13.9 Wolfe, W. L. and Zissis, G.J., The Infrared Handbook. Environmental Research Institute of Michigan (1996).

13.10 Mil-Std-2194, Infrared Thermal Imaging Survey Procedure Electrical Equipment.

13.11 American Society for Nondestructive Testing Standard Practice SNT-TC-1A, Qualifications Guidelines.

13.12 American Society for Nondestructive Testing Infrared and Thermal Testing Handbook, 2001.

13.13 American Society for Nondestructive Testing Level III Study Guide: Infrared and Thermal Testing Method, 2001.

Figure 6-1

Infrared Survey Results

In document Infrared Thermography Guide (Revision 3) (Page 165-175)