ML20238F096
| ML20238F096 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 04/01/1987 |
| From: | CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20238F076 | List: |
| References | |
| SP-87-040, SP-87-40, NUDOCS 8709150376 | |
| Download: ML20238F096 (7) | |
Text
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i Carolina Power & Light Company
!e, Brunswick Steam-Electric P.Iant i
i Unit.0 l
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l Wall Thinning inspections j
'Special' Procedure:
SP-87-040 Rev. 001 1
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1 Approved By:
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Datu GeneraTN(nager /ttanager Technical Support Date of Expiration:
12 31- %7 8709150376 B70910
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List of Effective Pages i
SP-87-040 Pace (s)
Revision 1
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BSEP/VOL. XC/SP-87-040 i
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1.0 PURPOSE This procedure provides the guidelines for the ultrasonic thickness measurements of piping components for the detection of wall thinning.
2.0 SCOPE This procedure covers.the use of longitudinal wave, pulse echo ultrasonic Instruments for the ultrasonic thickness measurement of carbon steel pip-Ing components such as forgings, castings and piping which have been identified for examination, by Technical Support-Discipline personnel 30 PERSONNEL REQUIREMENTS 31 Personnel performing ultrasonic testing in accordance with this pro-cedure shall meet qualification requirements as specified in Carolina Power & Light Company, Corporate QA Department procedure, NDEP-10
" Training, Qualification and Certification of Nondestructive Examina-tion Personnel" or a CP&L approved vendor certification procedure.
32 Only certified ultrasonic Level I inspectors working under the. direct supervision of a certified ultrasonic Level 11 or Level 111, or a certified ultrasonic Level 11 or Level ill inspector / examiner may per-form ultrasonic testing to this procedure.
4.0 EQUIPMENT REQUIREMENTS 4.1 The ultrasonic instrument shall be a pulse reflection (echo) type unit with A-scan presentation capable of transmitting, receiving and displaying signals within a frequency range of at least 1 MHz to 10 MHz. The unit shall have linear response within 25% for at least 80% of the vertical screen height and for at least 90% of a the horizontal sweep length.
Signal attenuators, if used, shall be accurate over the range used to t10% of the nominal attenuation ratio.
The instrument shall display visible evidence of a valid calibration.
4.2 The instrument calibration shall be performed and documented at intervals not to exceed 6 months or whenever maintenance is performed which affects the equipment function.
43 Transducers shall meet the following criteria:
431 Transducers may have up to 1.125" of active crystal diameter and a frequency between 1 MHz and 10 MHZ.
Transducers may be single or dual element type.
4.4 Any of the following may be used as a couplant:
2 Gylcerin, grease, oil, water, brand-name couplants.
45 The couplant to be used during thickness measurement shall also be used in calibration.
BSEP/VOL. XC/SP-87-040 page 1 of 5 Rev. I
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-5 0'LTEST CALIBRATION.
p 51. Calibration with Prepared' Standards 1
2 5 1.1 The instrument should be calibrated on a standard of the same basic material as the-item under test using thickness above and below the anticipated minimum wall thickness of'the' item under test.. Flat standards may q
be used for pipe and tubing 3/6 inch nominal diameter j
and greater. The Instrument shall be calibrated prior j
to each use and after any interruption in power supply.
5 1.2 The back reflection from the thinner standard shall be placed at the point on the baseline relating to the standard's.
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actual thickness by adjusting the delay' controls. The back J
reflection.from the thicker standard shall be placed at the-f point on the baseline relating to:lts actual thickness by i
adjusting the range controls. Repeat as necessary until no furtr,er adjustment is needed.
'5 1.2.1 As an alternate method, the multiple back reflection technique from a known thickness may.be used for instrument calibration. The material and range controls of the instrument shall be adjusted so the sound path distance is displayed linearly along the baseline of the screen tolinclude the anticipated examination range. -The first back reflection shall be placed at a. point on the baseline relating to the standard's actual thickness by adjusting the delay controls.
Repeat as necessary:until no further adjustment is needed.
513 The screen shall be set up in such a manner as to cause the smallest divisions of the graticule to be as small as prac-tical.
I 5 1.4 Any reading found outside the calibration range shall be cause for recalibration as necessary to bring the reading into the calibration range.
l 515 Calibration information shall be recorded on the Ultrasonic 1
Thickness Calibration Report (see Attachment 1).
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'6.0 SURFACE PREPARATION The contact surface shall be free of loose scale, dirt, rust and any other i
extraneous materials which would interfere with free movement of the r
transducer or the transmission of ultrasound into the item under test.
1 70 GRIOS a
71 Prior to inspect'.on an inspection grid shall be established on the
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component. The following guidelines may be used to, establish a grid:
i BSEP/VOL. XC/SP-87-040 page 2 of 5 Rev. 1 I
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grid line spacing may be in accordance with the following:
Nominal Pipe Size Grid Line Spacino 14" every 45
>4" to 8" every 300
> 8" to 12" every 200
>12" every 15 For components greeter than 16 inch nominal pipe size. Intersec-tion points along the grid lines estabilshed above shall be marked in 3 inch increments.
For all other component sizes these inter-sections points should be in 2 inch increments.
- For components encompassing different pipe sizes (eg. reducers) use the appilcable grid line spacing applicable to the smaller end of the component.
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- Grid lines should be numbered alphabetically in the circumferen-tial direction of the component and numerically along the axis of the component.
The 0 reference point should be permanently marked on the compon-i ent wherever feasible such that the grid can be relocated.
l Grid lines should be marked on the component surface by non-permanent marking methods such as paint, ink markers, etc.
Alternate gridding criteria may be used on a case-by-case basis if approved by the Project Engineer-ISI.
8.0 INSPECTION AND DATA RECORDING 8.1 The ultrasonic scope screen should oe marked to indicate minimum wall thickness (0.875 x nominal wall thickness) f or each component exam-ined.
8.2 Scanning should be performed randomly in the area bounded by the grid in an attempt to locate the lowest wall thickness.
8.3 A one inch area adjacent to circumferential welds should be complete-ly scanned on both sides of the weld.
S.4 The lowest wall thickness reading obtained should be recorded for each grid' point on the UT Thickness Measurement Report (see ).
85 Upon completion of each componant thickness readings, calibration shall be verified.
90 INSPECTION REPORTING 91 Inspection reports shall be turned over to the ISI Project Engineer for transmittal to the appropriate Technical Support-Discipline personnel.
BSEP/VOL. XC/SP-87-040 page 3 of 5 Rev. I
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ULTRASONIC THICKNESS CALIBRATION REPORT V
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'l Calibration Report No.
Instrument Model~
Instrument Serial No.
Transducer Type Transducer Serial No..
.Couplant Calibration' Standard-Standard Thickness' UT Measured Thickness Performed By Level Date BSEP/VOL. XC/SP-87-040 page 4 of 5 Rev. I e
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BSEP/VOL. XC/SP-87-Oh0 page 5 of 5 Rev. 1
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