Requirements & Preparation
It is the responsibility of the contracting persons to prepare the heat exchanger(s) and/or chiller(s) before Testing begins. Eddy Current USA, Inc. reserves the right to amend the contracting fee, reschedule, and/or cancel the test if the following detailed criteria are not met to a satisfactory level:
Access
Safe and adequate access to both the Site and Subject are considered mandatory pre-requisite conditions to the performance of testing.
Site
On-site access must be in accordance with the standards as established by OSHA (Standards-29 CFR 1926.34 – Means of egress) and (Standards-29 CFR 1910 Subpart D – Walking-Working Surfaces).
Subject
Subject must be accessible from at least one end, with a minimum of thirty-six (36) inches of unobstructed clearance in order to conduct the test.
Lock Out/Tag Out (LOTO)
Subject must be in accordance with the conditions of Lockout/Tagout (LOTO) as established by OSHA (Standards-29 CFR 1910.147 App A – Typical minimal lockout procedures).
Endcaps
Endcaps (i.e. heads, marine boxes) must be removed from at least one end of the test Subject prior to testing. Endcaps must be placed in a location where they do not impede the testing Procedure or pose a Struck-By Hazard.
Tube Cleanliness
Tubes contained within the test Subject must be free of foreign material, scale, and debris in order for the tube bundle to be tested.
Testing Procedure
All Testing performed by Eddy Current USA, Inc. will be done so according to a written and documented procedure, which, at a minimum, contains the requirements as outlined in Table T-823 of ASME sec V article 8, and establishes the value, or range of values, for each requirement.
Assessment
Prior to Testing, an Eddy Current USA, Inc. Technician will perform a preliminary assessment of both the Site and Subject. Testing will not begin until both Site and Subject have been found to meet the Preparation requirements.
Site
An Eddy Current USA, Inc. Technician will first complete a preliminary checklist of necessary steps and procedures in order to verify certain on-site information. Once this information is verified, the Technician will proceed with the Subject Assessment. If the state of the worksite is found to be unsatisfactory to the Technician, the identified issues will need to be resolved before proceeding to Subject Assessment.
Subject
An Eddy Current USA, Inc. Technician will complete a preliminary checklist of necessary steps and procedures in order to verify and document subject-specific information. Once this information has been collected and verified, the Technician will proceed with Setup. If the state of the work-subject is found to be unsatisfactory to the Technician, the identified issues will need to be resolved before proceeding with the Test.
Setup
Once the preliminary assessment has been completed, an Eddy Current USA, Inc. Technician will proceed with the setup of the Signaling Instrument, data recording equipment, and applicable Probe/Coil configurations.
Techniques
Absolute
The Absolute Coil Technique used to detect variations in the specific area being tested, without reference to a secondary coil or alternate test subject.
Differential
The Differential Coil Technique is used to locate and identify small, abrupt changes in conductivity, permeability, and/or geometry.
Cross-Axis (X-Axis)
The Cross-Axis/X-Axis Technique uses a hybrid-coil arrangement to detect material variations that can be classified as small volume, large volume, and/or circumferential.
Calibration
Absolute
- Phase Angle
Adjustments to the basis frequency of the Signaling Instrument will be made so that the phase angle of a signal from the O.D. Notches is between 50 deg. and 120 deg. rotated clockwise from the signal of the 100% Thru-Wall Hole.
- Sensitivity (Signal-to-Noise)
Sensitivity will be adjusted to produce a minimum peak-to-peak signal from the O.D. Notches of 30% of the full-scale horizontal presentation with the Signaling Instrument sensitivity set at 1 Volt(V) per division. This sensitivity will be referred to as a 3:1 Signal-to-Noise (3:1 S/N) Ratio.
- Phase Rotation
Adjustments to the basis frequency of the Signaling Instrument will be made so that the phase rotation of a signal from scanning motion (wobble), I.D. Groove, or both, is positioned along the horizontal axis of the display ±5 deg. Responses from the 100% Thru-Wall Holes and O.D. Notches will be maintained as described above.
Differential
- Phase Angle
Adjustments to the basis frequency of the Signaling Instrument will be made so that the phase angle between a line drawn from the origin to the tip of the response from the 100% Thru-Wall Hole and the horizontal axis is approximately 40 deg. The phase angle formed by a line drawn from the origin to the tip of the response of the O.D. Notches and the 100% Thru-Wall Holes is between 50 deg. and 120 deg.
- Sensitivity (Signal-to-Noise)
Sensitivity will be adjusted to produce a minimum origin-to-peak signal from the O.D. Notches of 30% of the full scale horizontal presentation with the Signaling Instrument sensitivity set at 1 Volt(V) per division. This sensitivity will be referred to as a 3:1 Signal-to-Noise (S/N) Ratio.
- Phase Rotation
Adjustments to the basis frequency of the Signaling Instrument will be made so that the signal response due to probe rotation (wobble), I.D. Groove, or both, is positioned along the horizontal axis of the display ±5 deg. Responses from the 100% Thru-Wall Holes and O.D. Notches will be maintained as described above.
Cross-Axis (X-Axis)
- Phase Angle
Adjustments to the basis frequency of the Signaling Instrument will be made so that the phase angle between a line drawn from the origin to the tip of the response from the 100% Thru-Wall Hole and the horizontal axis is approximately 60 deg. The phase angle formed by a line drawn from the origin to the tip of the response of the O.D. Notches and the 100% Thru-Wall Holes is between 65 deg. and 100 deg.
- Sensitivity (Signal-to-Noise)
Sensitivity will be adjusted to produce a minimum origin-to-peak signal from the O.D. Notches of 20% of the full scale horizontal presentation with the Signaling Instrument sensitivity set at 1 Volt(V) per division. This sensitivity will be referred to as a 3:1 Signal-to-Noise (S/N) Ratio.
- Phase Rotation
Adjustments to the basis frequency of the Signaling Instrument will be made so that the signal response from the Tube Land Nominal is located at the Zero-Point Horizontal Baseline.
Testing
Once all preliminary Assessment and Setup is completed, Testing will be performed on 100% of the tubes in the tube bundle unless otherwise specified in the Purchase Order or through failure to meet Requirements & Preparation. All tubes NOT Tested will be identified on the final Report Document.
Identification
All Indications meeting or exceeding the 3:1 Signal-to-Noise ratio qualifier will be identified; their location and relevant signal data recorded and categorized for later compilation in the final Report Document. At the Technicians discretion, relevant Indication data that fails to meet the 3:1 Signal-to-Noise ratio will be included in the final Report Document. All Indications will be categorized as either Non-Detrimental, Potential Defect, or Defect.
Verification
It is not uncommon for non-native tube materials to accumulate within the Inner Diameter or on the Outer Diameter of the tube, creating false-positive Indications and/or movable Indications. For this reason, all Indications will be checked and verified before being recorded and categorized.
Evaluation
Upon full completion of the Test Scan, the Technician will perform an informal field evaluation of the state of the tube bundle. This field evaluation may relate to immediate defect Indications, general confirmation of suspected issues, the overall integrity of the tube bundle, or any other information the Technician feels relevant to the immediate operation of the containing vessel.
Post-Test
After the Testing and Evaluation has been completed, the Technician will commence with Post-Test procedures: dismantling the recording and testing equipment, cleaning and returning to storage any and all equipment and property belonging to Eddy Current USA, Inc., general cleaning of the work area when necessary, etc. Once the site has been returned to the same state as Pre-Setup, the eddy current test can be considered completed.
Analysis
Analysis of Indications will be performed, compiled, and documented by the Technician responsible for the test. This analysis will take into consideration all essential variables necessary to adequately provide a detailed description of the state of the tube bundle tested. Results of this analysis, along with any recommendations of actions to be taken, will be documented in the final Report.
Recommendations
After analysis, recommendations on any corrective action necessary to the performance and operation of the vessel tested will be documented. Recommendations can include, but are not limited to, improved cleaning methods to increase scan sensitivity, additional non-destructive testing to further verify Indications, continued monitoring of Indications for propagation, or the removal of tubes for enhanced visual inspection.
Documentation
All Essential and Non-Essential variables necessary for the non-destructive testing method will be documented within the final Report. Any and all deviation from the established baseline range of values for Essential and Non-Essential variables will be documented within the final Report.
Report
All information contained in the final Document Report will contain, at a minimum, all Essential and Non-Essential variables and data as defined in ASME sec. V article 8 Table T-823, and T-841. Any variation, deviation, or otherwise change to and standardized data will be noted.
Calibration Settings
Calibration Settings, both Standard and Non-Standard, for all equipment used in the testing procedure will be detailed in this section.
Standard Tube Material
Standard Tube Material, signal magnitude standards, and all tube material data relevant to the testing procedure (e.g. tube wall thickness, tube length, support distances, etc.) will be detailed in this section.
Eddy Current Test Data
Eddy Current Test Data including tube location, indication location inside the tube, amplitude and magnitude, and specific indication type will be detailed in this section.
Tube Sheet Diagram
Tube Sheet Diagrams will be of the entire tube bundle layout with specific indication information detailed for each tube. Reference Legends for row and tube count, as well as the specific indication, will be provided.
- Tube Sheet Image
When applicable, a high resolution image of the state of the tube bundle layout and tube sheet will be provided.
Eddy Current Test Summary
Eddy Current Test Summary data will include general and specific information on the entirety of the testing procedure. Specific sections of the Summary are as follows:
Overview
Summary Overview data will include all Indications detected during testing, categorized into three distinct groupings: Non-Detrimental, Defect, and Restricted/Inaccessible. A full accounting of specific Indication type, their number, and percentage of tube bundle affected will be detailed in the Overview.
- Non-Detrimental
Indications that do not appear to have any significant effect on the performance or longevity of the tube bundle will be classified as Non-Detrimental.
- Defect
Indications that appear to have a significant effect, or present the possibility for significant effect, in the performance and longevity of the tube bundle will be classified as Defect.
- Restricted/Inaccessible
Tubes that are unable to be tested from end to end due to physical obstruction inside the tube, will be classified as Restricted. Tubes that are unable to be tested at all, and are not plugged or otherwise removed from tube bundle operation, will be classified as Inaccessible.
Considerations
Detailed information regarding specific Indication classification (e.g. ID/OD, MLIB/MLAS, PFD, etc.) as well as an assessment of the integrity of the tube bundles Inner Diameter and Outer Diameter will be provided in this section.
Recommendations
Recommended actions regarding length of time between tests, corrective actions for specific indications, and notes specific to the test (provided by the Technician) will be detailed in this section.