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Daniel DettmersIndustrial Refrigeration Consortium

University of Wisconsin - Madison

Overview ofNon-Destructive Evaluation

Methods for Mechanical Integrity

229 CFR 1910.119

• Written procedures to maintain the integrity of vessels, piping systems, safety relief systems, emergency shutdown systems, controls, and rotating mechanical equipment –1910.119(j)(2)

• Appropriate training for personnel involved in process maintenance activities – 1910.119(j)(3)

• Inspection and testing procedures in accordance with industry-recognized or manufacturer-recommended practices –1910.119(j)(4)

• Methods for correcting equipment deficiencies identified and that fall outside of acceptable limits as defined by processsafety information – 1910.119(j)(5)

• Techniques to insure the quality of system construction, operations, and maintenance of equipment used within the covered process – 1910.119(j)(6)

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Definition of Mechanical Integrity Inspection Program

Activities undertaken to provide assurance that mechanical equipment

is designed, fabricated, procured, installed, and maintained in a manner

appropriate for its intended application.

4Elements of a MI Program

(Appendix C to 1910.119)

• Identification and categorization of equipment and instrumentation

• Inspections and test methods• Testing and inspection frequencies• Development of and conducting appropriate

maintenance procedures• Training of maintenance personnel• Establishment of criteria for acceptable test results• Documentation of test and inspection results• Documentation of manufacturer recommendations as to

meantime to failure for equipment and instrumentation

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What Are We Looking For?• Prevention of Failures Due To:

– Corrosion and Erosion– Stress Corrosion Cracking– Brittle Fracture– Blockage or Restricted Flow

• Other– Verify Pipe Thickness– Foreign Object Detection or Location– Verify Valve Position– Weld Location and Identification

• Other Damage?

6Nondestructive Testing

“Nondestructive testing has been defined as comprising those test methods used to examine or inspect a part or material or system without impairing its future usefulness.”

– American Society for Nondestructive Testing

• Nondestructive Testing (NDT) - just to test methods and test equipment

• Nondestructive Inspection (NDI) - written requirements, procedures, personnel, standards, and controls

• Nondestructive evaluation (NDE) - the decision making process from interpretation to decision making

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Critical Refrigeration Components• Pressure Vessels and Storage Tanks

[19190.119(j)(1)(i)] • Piping Systems (including piping components such

as valves) [19190.119(j)(1)(ii)]• Relief and Vent Systems and Devices

[19190.119(j)(1)(iii)]• Emergency Shutdown Systems [19190.119(j)(1)(iv)]• Controls (including monitoring devices and sensors,

alarms, and interlocks) [19190.119(j)(1)(v)]• Pumps [19190.119(j)(1)(vi)]• Compressors• Evaporators• Condensers

8MI Regulations & Guidelines

OSHA (Occupational Safety & Health Administration)– Process Safety Management

ASME (American Society of Mechanical Engineers)– ASME B31.5 Refrigeration Piping and Heat Transfer

ComponentsIIAR (International Institute of Ammonia Refrigeration)

– Standard 2-1999 American National Standard for Equipment, Design & Installation of Ammonia Mechanical Refrigerating Systems

– Standard 3 Draft American National Standard (Trial Use) for Ammonia Refrigeration Valves

– Bulletin 109 Guidelines for: IIAR Minimum Safety Criteria for a Safe Ammonia Refrigeration System

– Bulletin 110 Guidelines for: Start-Up, Inspection and Maintenance of Ammonia Mechanical Refrigerating Systems

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Screening vs. ScanningScreening - a rapid inspection of as much of the system

as is possible in the time allotted, looking for obvious flaws and areas requiring further inspection scrutiny– Larger areas of pipe inspected– Sacrifice detection and precision

Scanning - inspecting to maximize the detection of flaws and the level of detail on each flaw– Maximize detection and precision– Sacrifice speed, increase cost

• Screening often precedes scanning• Some techniques may provide varying degrees of

compromise

10Inspection Scope

Global Examination – The entire system is examined, usually by a screening method.

Preferential Examination – The entire system is screened, but areas of concern are scanned

Specific Examination – Only specific areas examined. (Difficult to service or problem areas such as welds, elbows, vessels, etc.)

Inspection Points – Specific points are established and inspected yearly to determine the corrosion rate. Assumed these points show a representative sample of the system.

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NDT Technology Selection

• Examination objectives• Inspection program motivation• NDT technology capabilities & limitations• NDT technology cost• Orientation and accessibility of the test piece• Test piece geometry and size• Internal variables in densities of the material• Possible location and orientation of

discontinuities

12Standard NDT Methods

Surface Inspection Methods:– Visual Inspection– Liquid Penetrant– Magnetic Particle

Volumetric Inspection Methods:– Ultrasonic– Radiographic– Eddy Current

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Visual Inspection

• Screening technique• Looking for obvious areas

for further inspection– Water damaged insulation– Visible corrosion– Distorted piping

• Technology can assist– Magnifiers– Borescope– Video recording

14Liquid Penetrant

• Scanning technique• Process

– Apply penetrant– Apply developer– Residual penetrant shows surface cracks

• Inexpensive, sensitive, multiple materials, independent of orientation, low skill

• Surface discontinuities only, surface cleaning necessary, low temperature items may be difficult depending on liquids

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Magnetic Particle Inspection

• Scanning technique• Process

– Magnetize test piece– Apply magnetic particles– Particles align themselves along flaws

• Inexpensive, sensitive, magnifies flaws, surface and subsurface flaws detectable

• Ferromagnetic materials only, field must be 45º to 90º to flaw, requires skill

16Ultrasonic Testing

(Contact Method)

• Scanning/screening technique• Process

– Apply couplant to transducers– Transmitter transducer sends signal– Signal bounces off flaws and walls and is received

by receiver transducer for interpretation• Sensitive, internal inspection method, many

control variables, adjust to specimen• Requires skill and training, too sensitive,

limited by geometry and surface of test piece

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Basic Ultrasonic Testing Methods

• Pulse echo technique– Transmitter and receiver

combined

• Transmission technique– Pulsed or continuous – Requires 2 transducers

• Reflection technique– Compare reflection times

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Digital Ultrasonic Thickness

Meter

• Combined transmitter/receiver transducer

• Used to establish thickness of materials

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Guided Wave Ultrasonic Inspection

• Rapid screening tool• Long range examination• Ultrasound is transmitted and

received from a single location• Determine range and circumferential

orientation of detected flaws• Capable of inspecting otherwise

inaccessible piping• Signal response function of depth

and circumferential extent of detected flaw

Emerging Technology

20Guided Wave Ultrasonic Inspection

Capabilities– Can be performed while system on-line– Theoretically scans over 100 feet– Suitable for pipe sizes up to 24 inches in

diameter– Scans buried and

insulated pipe– Discern erosion/corrosion

and cracking from welds, supports, etc.

Emerging Technology

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Guided Wave Ultrasonic Inspection

Limitations– Mastic, insulation, earthen materials may

attenuate the ultrasound significantly– Meant to be used as a screening tool to identify

areas needing additional NDE– Multiple elbows may result in incorrect location

identification of flaws– Heavily corroded pipe in general may produce

un-interpretable results– Detection limited to loss of cross sectional area

can miss significant defects

Emerging Technology

22Radiographic Testing

• Scanning technique• Process (typical)

– Beam of radiation applied to test piece– Test piece attenuates beam based on composition– Radiation beam is detected and/or displayed

• Sensitive, internal inspection method, great detail with small film grain

• Requires skill and training, radioactive sources require greater safety, expensive

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Radiographic Testing

• Radiation type– High energy photon (X-ray, gamma (γ))– Collimated neutron beam

• Detection systems– Radiography (exposed film, fluorescent

screen, lead screen)– Radioscopy (fluoroscope, X-ray sensitive

television cameras)– Tomography (evaluation method)

24Ir192 Gamma Radiographic Camera

• Used to create radiographic images

• Penetrates nearly any material for the detection of internal defects or internal components

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Digital Radiographic Profiler

• Scanning tool to look at wall thickness without removing insulation

• Uses X-ray or Gd153 source– Gd153 must be replaced every 2 years

• Portable profiler picks up beam with MCP x-ray detector that can be adjusted around restrictions

• Produces pulse outputs instead of images

Emerging Technology

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Photo from Lixi, Inc. via Conam

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Digital Radiography Scanner

• Modular Track Design– Horizontal and Vertical Piping– Axial, Tangential, and

Circumferential Exams

• Detects Corrosion• Scans at 60 inches

per minute (0.06 mph!)

Southwest Research Institute

Emerging Technology

28Eddy Current Testing

• Scanning technique• Process

– Eddy currents induced in test piece– Eddy currents in test piece sensed and interpreted

• Sensitive, surface and subsurface detection, non-contact, not too expensive, fast results

• Requires skill and training, requires material that is electrically conductive or magnetic

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Hiring a NDT Contractor• Check Qualifications

– At least 5 years experience and SNT-TC-1A certification (ASME B31.5)

• Consult prior to their arrival– Explain your system & operation

• Materials present• Operational temperatures• Critical components

– Explain what defects you expect– Ask what defects they would expect– Disclose what standards you require them to test to

?

30Hiring a NDT Contractor

• Plan for the future– Pick a firm that will be

around 20 years– Establish a baseline and

plan for future inspections

• If insulation is to be removed, consult with your insulation contractor– It may be cheaper to re-insulate a vessel then just

replace plugs

• Document everything

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Hiring a NDT Contractor

Remember, their specialty is in metallurgy, material testing and

evaluation of the results. They are not experts at refrigeration and may not

know anything about what components are critical to the refrigeration system or

OSHA’s Process Safety Management requirements for this industry.