Ultrasonic Procedure [PDF]

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ULTRASONIC INSPECTION PROCEDURE

Author Approved By Revision No.

Name Gary E. Kinter

Reviewed By

APPROVAL Function ASNT Level III UT REVISION HISTORY Approved By

Date 2-5-2013

Signature

Date

Signature

INDEX 1.0

SCOPE

2.0

DESCRIPTION

3.0

APPLICATION DOCUMENT

4.0

PERSONNEL

5.0

EQUIPMENT

5.1

APPARATUS

5.2

SEARCH UNIT

5.3

COUPLANT

5.4

BASIC CALIBRATION BLOCKS

5.5

BASIC CALIBRATION HOLE

5.6

CALIBRATION

6.0

PROCESS

6.2

APPLICATION

6.3

ANGLE BEAM

6.4

EXAMINATION PROCEDURE (ANGLE BEAM)

6.5

STRAIGHT BEAM METHODS

6.6

EXAMINATION PROCEDURE

6.7

TESTING AND PIPE MATERIAL

7.0

ACCEPTANCE STANDARD

8.0

ILLUSTRATION SCAN TECHNIQUE

A.

REPORTS

SUBJECT: ULTRASONIC EXAMINATION 1.0

2.0

SCOPE 1.1

This procedure covers the requirement for Ultrasonic examination of any welded material of any size, shape, thickness or configuration capable of conducting sound as may be required by the client specification and by various codes under which a component, or system is being designed and manufactured.

1.2

EDEMAC certifies that this document meets the minimum requirements of the ASME section V. Article V. and any other code or specification reference methods of Ultrasonic examination as defined by ASME section V. Articles

DESCRIPTION 2.1

Ultrasonic examination of materials by the pulse-echo method uses straight-beam longitudinal waves introduced by direct contact of the search unit with the material being examined. It series of electrical pulses, is applied to a piezoelectric element (transducer) which converts these pulses to mechanical energy in the form of pulsed wave at a nominal frequency. The transducer is mounted in a holder so it can transmit the wave into the material through a suitable wear surface and couplant. The assembly of transducer, holder wearface, and electrical connector comprise the search unit. The Ultrasonic instrument amplifies the electrical signal from the transducer and displays the reflection and a CRT screen. The normal presentation on the CRT screen is the “A Scan” with distance or metal travel read left to right on the horizontal trace and the amplitude of the vertical signals represent magnitude of the reflect surface.

2.2

No useful quantitative information can be obtained with standard Ultrasonic methods without first carefully calibrating as to metal travel and reflector size vs vertical signal amplitudes.

3.0

APPLICABLE DOCUMENTS 3.1

The following documents are made a part of this procedure to the extent specified. American Society of Mechanical Engineer (ASME) Section I Power Boiler Section VIII Pressure American National Standard Institute (ANSI) B31.1 Power Piping B31.3 Chemical plat / Petroleum Refinery Piping American Society for Testing and Material (ASTM) E 164 Standard Method for Contact Inspection of Welding American Society for Non- Destructive Testing (ASNT) SNT-TC 1A NDT Personnel Qualification and certification EDEMAC SERVICES QA Examiner Personnel Qualification and Certification

4.0

PERSONNEL 4.1

Personnel performing Ultrasonic examination to this procedure shall be qualified and certified in accordance with SNT-TC 1A table 1-c, QA Examiner personnel Qualification and certification.

4.2

Personnel responsible for performing Ultrasonic Examination to this procedure shall be certified as level I (Operator) Level II (Inspector) or Level III (Inspector Examiner)

4.3

Only certified Level II or level III personnel shall make determination as to the acceptability of the Ultrasonic indication.

5.0

5.2

5.3

EQUIPMENT 5.1

APPARATUS: An Ultrasonic, pulsed, reflection type of instrument shall be used for this inspection the minimum frequency range of the system shall be 1 to 5 MSZ. It shall have calibrated decibel control (accurate over its useful range to +/-20% or +/-201b of the nominal attenuation ratio) which allow measurement of signals beyond the linear range of the instrument.

a.

The Ultrasonic Instrument shall provide a linear presentation (within +/-5 percent for at least 75% of the screen height) sweep-line to top of screen.

b.

Calibration Frequency: Equipment shall be calibrated every six months. Calibration records shall maintained at the job site where the equipment is being utilized (see para 5.6).

SEARCH UNIT 5.2.1 Straight beam transducers shall have to nominal frequency or 2.25 MHZ unless variables such as grain structure material thickness etc. require the used of other frequencies 5.2.2

Angle beam transducer shall have a nominal frequency of 2.25 MHZ unless varies such as grain structure, material thickness etc. require the use of other frequencies.

5.2.3

The refracted angle of the sound beam in the production material shall be between 40- 75 degree inclusive. Table 1 lists the recommendation.

5.2.4

Transducer shall be fitted with suitable shoes as required to maintain adequate sound penetration transducers to maintain proper sound beam angle in the part.

5.2.5

Supplemental transducer shoes for curved surface shall have the same nominal radius of curvature as the material examined.

5.2.6

Transducer shall be used at their rated frequency

COUPLANT

5.3.1

5.4

A suitable couplant having good wetting characteristics such as liquid detergent or paste and water shall be used. The same couplant shall be used for calibration and examination. The sulfur and halogen content of couplant shall not exceed 1% by weight.

BASIC CALIBRATION BLOCKS 5.4.1

Drilled hole shall be used as basic calibration reflector to establish a primary reference response of equipment and to construct a distance –amplitude correction curve. These holes shall be located either in the production material or in a basic calibration block or similar metallurgical. Structure and the same or an equivalent. P-number grouping as the production material. For the purpose of this procedure Pnumbers 1, 3, 4 and 5 material considered to be equivalent.

a.

The thickness of basic calibration blocks if used, shall be related to the finished component thicknesses as shown in figure 1 where two more thicknesses are involved, the calibration block thickness shall be determined from the thickness of the component where the search unit is applied.

b.

For examination of circumferential welds will contact surface curvatures greater than 20-in diameter, that basic calibration blocks or block of essentially the same curvature as the part to be examined shall be used

5.5

c.

The basic calibration block contact surface shall be curved for contact surface curvatures of less than 20-in diameter. A single curved basic calibration may be used to calibrate the examination on contact surface in the range of 0.9 to 1.5 times the basic calibration block diameter. For example an 8-in diameter curved block may be used to calibrate the examination on contact surface in the range of curvature range from 7.2 to 12-in diameters. The curvature range from 0.94 to –in diameter requires 6 block curvature as indicated in figure 4.

d.

The basic calibration block for examination of longitudinal welds shall be of essentially the same nominal diameter as the part to be examined, except that for diameter greater than 20 inches, flat block may be used.

BASIC CALIBRATION HOLE 5.5.1 The basic calibration hole shown in figure 3 shall be drilled parallel to the contact surface of the basic calibration block or the component. The location depth and diameter of this hole shall be obtained from the table in figure 3. 5.5.2

However other calibration reflectors may be used provided equivalent response to that from the basic calibration hole are demonstrated. Reference Figure 1 and 2.

5.6

CALIBRATION 5.6.1 Calibration of the probes for beam angle is required on the IIW (International Institute of Welding) test block or other approved alternative (for example the V2 block) at least daily calibration of the flaw detector time base and amplification shall be carried out before examining each weld.

6.0

PROCESS 6.1 SURFACE PREPARATION 6.1.1 Contact surface the finished contact surface shall be free from weld spatter and any roughness that would interfere with free movement of the search unit or impair the transmission of Ultrasonic Vibration.

6.1.2

Weld surfaces: The weld surface shall be finished so it cannot mask or be confused with reflection from defects and should merge smoothly into the surface of the adjacent base materials.

6.1.3

Base Material: The volume of base material through which the sound will travel in angle beam examination shall be completely scanned with a straight beam search unit to detect reflectors which might affect interpretation of angle beam results. This is not intended as an acceptance reflection examination.

6.2

APPLICATION 6.2.1 The principal objective of the method given herein is the detection, location and evaluation of defects within the weld and heat affected zones. The welds shall be examined by the angle beam method where practical. In the examination of weldments where geometry or the condition described in 6.1.3 does not allow angle examination from both sides of the weld from single surface or a combination of surface, either a combination of angle beam and straight beam or straight beam in two (2) directions at 90 degrees to each other shall be used.

6.3

ANGLE BEAM METHODS 6.3.1 Distance- Amplitude Correction:-Compensation for the distance traversed by the Ultrasonic beam as it passes through the material is provided by the used of the curves shown by figure 5. or electrically. a.

Determination of Curves: Distance amplitude correction curves shall be constructed by utilizing responses from the basic calibration described in 5.5. The first point on the curve is obtained by placing the search unit as near as possible, but not less that 3/8 vee-path or 2-in whichever is less from the calibration hole and positioning for maximum response.

b.

The gain control is then set so this response is 80 percent of full screen on the cathode ray tube (CRT) This is the primary reference response.

c.

Without chaining the gain, the search unit shall be placed similarly at other position covering the expected examination distance range, and the corresponding response marked or the CRT screen.

d.

These points are joined by a smooth line whose length should cover the examination range. See figure 5.

6.3.2

Electronic Distance Amplitude Correction: If an electronic distance – amplitude correction device us used primary reference response shall be equalized at 50 percent of full CRT screen height over the distance range to be employed in the examination.

6.3.3

A

B

Transfer Method: Transfer method is used to collate the responses from the basic calibration block and from the component. Transfer is accomplished by noting the reference reflector in the basic calibration block and from component and correcting for the difference. The reference reflector may be “V” notches (which must subsequently be removed), an angle beam search unit acting as a reflector, or any other reflector which will aid in accomplishing the transfer.

V-NOTCH TRANSFER TECHNIQUE *

A “V” Notch may be placed in the basic calibration block. As an example, this notch may be 1-in long, have a depth of 1 percent of the block thickness and have an included angle such that the side of the “V” – Notch are perpendicular to the incoming sound wave. Another “V” notch having the same dimension may be placed in or adjacent to the weld beam.

*

The Search unit is positioned for maximum response from the notch in the basic calibration block and response reading is recorded. Then the search unit is positioned for maximum response from the notch in the test material to be examined and this response reading is also recorded.

*

After determining the above readings. It is necessary to correct the response obtained from “V” notch in the test material to the response level from the “V” –notch in the calibration block by adding or subtracting attenuation (db)

*

The original distance amplitude correction curve can now be used for signal amplitude rejection of flaws.

PITCH CATCH METHOD When “V” –notches are not permitted in the test material, the pitch catch method may be used. In this method, a second angle beam search unit is used to receive the sound transmitted by the search unit which is to be ultimately used in the examination. *

Connect the second angle search unit to the receive connection of the instrument and switch on the calibration block and manipulate the two search units until a maximum response is shown on the CRT mark this level on the CRT

*

The transit and receive search units are then placed on the production material so that the sound beam travels from the single transmit search

unit through the material and into the receiver unit. It is again necessary to peak in the response and mark the level on the CRT. As with the “V”-notch method, correct the response from the test material by adding or subtracting attenuation (db). Following disconnection of the receive search unit and switching of the instrument back to the pulse-echo method, the distance-amplitude correction curve originally drawn on the CRT screen is satisfactory for use as a signal amplitude rejection level.

C

FREQUENCY OF TRANSFER METHOD USED * Vessels: The transfer method shall be used at least once for each 10 feet of weld or less per plate and shall be performed at least twice for each type of welded joint. *

6.4

Piping: The transfer method shall be used as a minimum once for each welded joint for pipe size 10 inches in diameter and over, once for each 5 feet of weld for pipe less than 10 inches in diameter.

EXAMINATION PROCEDURE (ANGLE BEAM) 6.4.1 Coverage: Where possible, butt welds shall be examined over 100% of the area from both side of the weld usually from only one surface. 6.4.2

Scanning: When possible, scanning shall be performed at a gain setting of 2 times or 6 db the reference level sensitivity. a.

To assure complete coverage of the examined material each pass of the search unit shall overlap a minimum of 10 % of the transducer width. The rate of manual scanning shall not exceed 6 inches per seconds.

6.4.3

Reference Level: The reference level sensitivity for evaluating discontinuities is the primary reference response corrected for distance by the distance amplitude curve or electronically, and modified by the transfer method, if used.

6.4.4

DETECTION OF DISCONTINUITIES PARALLEL TO THE WELD a. Scanning Method: The search unit shall be placed on the contact surface with the beam aimed at about 90 degrees to the weld and manipulated laterally and longitudinally so the Ultrasonic beam passes through all of the beam to the reflector.

b.

6.4.5

6.5

Two search units technique: Technique using two search units may be used to detect lack of penetration in double welded butt joints.

DETECTION OF DISCONTINUITIES TRANSVERSE TO THE WELD If the weld surface has been made sufficiently smooth, the search unit may be placed on the center line of the weld and the beam directed along the weld to scan the entire depth and width of the weld. As an alternate, two search units may be placed on the contact surfaces adjacent to the weld, one on each side forming an angle of 45 degrees or less with the axis if the weld.

STRAIGHT BEAM METHODS 6.5.1 Calibration of equipment a. Distance- Amplitude Correction: A distance amplitude correction curve need not be constructed when the thickness of material is less than 1 – inch. For thickness using the proper basic calibration block (see figure 1 and 2), the search unit shall be positioned for maximum response from the basic calibration hole at ¼ T and the signal amplitude shall be adjusted to 50% of full CRT screen. This is the primary reference response. Without changing the gain control, the search unit shall then be positioned for maximum response from basic calibration hole at 3/4 T, its amplitude marked on the CRT screen and the two points joined with a straight line extended to cover the test range.

6.6

b.

Electronic Distance-Amplitude Correction Device: The primary reference response shall be equalized over the distance range to be employed in the examination.

c.

reference Level: The reference level for monitoring discontinuities is the primary reference response corrected by a distanceamplitude curve or electronically.

EXAMINATION PROCEDURE 6.6.1. Scanning Motion: The weld shall be examined by moving the search unit progressively along and across a sufficient contact area so as to scan the entire weld

6.6.2

Sensitivity Level: When possible, scanning shall be performed at a minimum gain setting of twice (6 db) the primary reference level.

Evaluation of discontinuities shall be done with the gain control set at the reference level. 6.6.3

Monitoring of Procedures: Penetration shall be verified by (1) obtaining a reflection from an opposite parallel surface, or (2) obtaining the back reflection o similar material while using approximately the same length of sound travel.

6.6.4

To assure complete coverage of the examined material each pass of the search unit shall overlap a minimum of 10% of the transducer width. The rate of manual scanning shall not exceed 6-inches per second.

6.6.5

Evaluating of Indications: All indication which produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can evaluate the shape, identity, and location of all such reflectors in terms of the acceptance – rejection standards of the referencing cid section.

6.7

TESTING AND PIPE MATERIAL 6.7.1 Ultrasonic testing practice shall be in accordance with BS 5996 using technique 2 (Flaw echo / bottom echo ratio for sizing the lamination), or technique 3 (multiple echo pattern), depending on wall thickness and type of lamination (if any) encountered. The probe shall be scanned in a zigzag fashion in a zone 100mm wide around planned cut-outs for nozzles, and back from the new end of pipes which have been cut. Laminar defects shall not be accepted if they exceed 6-mm in any dimension. Any lamination not parallel to the pipe surface shall be deemed unacceptable.

7.0

ACCEPTANCE STANDARDS

7.1

All indications which produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such reflectors and evaluate them in terms of the acceptance rejection standard as follows:

7.2

Discontinuities are unacceptable if the amplitude exceeds the reference level and discontinuities have lengths which exceed.

a. b.

¼ - inch font up to ¾ - inch inclusive 1/3 –inch font from ¾ -inch to 2 ¼ - inch inclusive ¾- inch font over 2 ¼ - inch

Note: Where this the thickness of the weld being examined, if a weld joins two members having different thickness at the weld, this the thinner of these two thickness. 7.3

Where discontinuities are interpreted to be cracks, lack of fusion and incomplete penetration, they are unacceptable regardless of length.

7.4

EXAMINATION OF REPAIRS: 7.4.1 Repairs shall be re-examined by the same procedure used for original detection of the discontinuity

7.5

ACCEPTANCE STANDARD 7.5.1 Defects shall be identified primarily by accurate positioning of the source of the echo in the weld cross section, and their approximate orientation determined by comparing the echoes received from each. When the examination show indication of a defect the following shall apply. a.

All reflection giving an indication in excess of 20% DAC shall be investigated to the extend that they can be evaluated in terms of the acceptance standard.

b.

All reflector giving an indication in excess of 50% DAC shall be investigation to the extend that they can be evaluated in term of acceptance and recorded on the report.

c.

All reflectors in excess of 100% DAC shall be cause for rejection.

7.5.2

Any weld, which as a result of ultrasonic examination, and which in the opinion of the company exhibit imperfection greater than the limits stated in API-1104, latest edition or as superseded in this article shall be considered defective and shall be so be marked with an identification paint marker. In addition to the API-1104 requirements, the welds containing, cracks, including crater cracks regardless of size or location, shall be deemed unacceptable. Arc burns or strikes shall be deemed unacceptable and shall for sour service gas/ oil lines addition to the API 1104 requirements, the following shall apply

8

a.

Any amount of inadequate penetration of the root bead as defined by API-1104 shall be unacceptable.

b.

Any amount of incomplete fusion between the root and the level as defined by API 1104 shall be unacceptable

c.

Un-repaired burn-through area shall be unacceptable

REPORTS 8.1 Ultrasonic examination Inspection Report shall be filled out completely by qualified personnel and the report shall be signed by the certified inspector. 8.2

All recordable indications shall be shown on the technique sheet. Copies of technique sheet (s) shall be submitted with each inspection report

8.3

A test report shall be issued for each weld with all the relevant data, including but not limited to the following

a.

Report number

b.

Weld number

c.

Isometric / Line Number

d.

Material thickness

e.

Couplant

f.

Probes used, size and frequency

g.

Calibration technique

h.

Surface condition

i.

Name of Operator

B

j.

Acceptance Code

k.

Reportable defects and disposition and sketch

l.

DSG

Probe calibration Chart

THICKNESS CHECK MEASUREMENT

SCOPE The scope of work describe in this page spelt out requirement necessary for the corrosion monitory wall thickness examination of vessel, process lines and facilities. QUALIFICATION OF PERSONNEL a. ULTRASONIC INSPECTION Inspector shall hold a current certificate of proficiency in ultrasonic issued by a national recognized certification scheme for non- destructive testing (ASNT) shall be used for the purpose of qualification of personnel. Alternatives qualifications shall only be deemed acceptable with the prior consent of the client and / or inspecting authority. EQUIPMENT AND MATERIAL a. Ultrasonic flow detectors with a well define A- scan present b.

ULTRASONIC CALIBRATION BLOCKS i) ii) iii)

IIW v/1 calibration blocks IIW v/2 calibration blocks IOW beam profile blocks

c. ULRASONIC PROBES 10mm to 25mm crystal diameter probes shall be used a frequency 2 MH Z to 5 MHZ. The types of probe required depend on the thickness of the material being examined. TYPES OF PROBE i) Angel probe ii) Normal probe iii) Transmit probe PROBE SENSITIVITY Compression Wave Probe – Longitudes A minimum of 40dB of gain shall be in reserve when the first back wall echo from the dimension of the IIW/I block is set at 100% full screen height.

ii)

sheave wave probe – transverse A Minimum of 40dB of gain shall be in the 100mm quadrant on the IIW V/I block is set at 100% full screen height.

RESOLUTION OF PROBES Sheave Wave Probe: IOW beam spread block shall be used to assess resolution. This should be done accordance to the acceptance standard. COMPRESION WAVE PROBES Resolution shall be assessed using the IIWV/I calibration shall be considered acceptance when the three echoes at 100mm, 91mm and 85mm are clearly defined. BEAM PROFILE The beam spread of probes shall be established using the I0W block and 20dB drop method and beam profile recording on the tracing paper or clear Perspex. OTHER EQUIPMENT Calibrated Rule Tape measure Welding Gauge Flaw light location plotting board THICKNESS SURVEY OF PIPING Isometric drawing is usually employed in representing pipelines with particular reference to welds, valves, pumps, flanges and cap ends. The position of each measurement point clearly marked and referenced to the nearest up weld, value etc. MEASUREMENT a. Vertical piping work and pipe work inclined at 450 to horizontal: Four measurements shall be made around the circumference of the pipe located at plat- form North and South (or East and West) and top and bottom of pipe.

Top East

North

West

North - west

South

VERTICAL

South Bottom HORIZONTAL

b. Horizontal Reading: Requirement with pipe work inclined at 45 0 horizontally, see sketches above. Other methods of measurement include ultrasonic reading. The procedure for method forms the basis for the data management system and is specific for the individuals piping items. A grid scan at 100% can be carried out as suspect area of piping with evidence of gross corrosion or significance loss wall thickness.

THICKNESS SURVEY OF VESSELS Sketches are always produced for any vessels to show the plan and elevation, nozzles welds, flanges plate etc of vessels. The measurement positions are normally marked on the vessel concerned before reading are taken. It is normally advisable to apply permanent markers on the reset to show measurement position. READING PROCEDURE: Outside

South West

North East

VERTICAL

Outside

Bottom

Top

HORIZONTAL

One measurement position on outside of bend at mid point Bend 1:6 Outside

Inside South West VERTICAL

HORIZONTAL OUTSIDE

INSIDE BOTTOM HORIZONTAL 1. 2.

Measurement position on outside of bend equally spread. Measurement position on each side of bend at similar position as those on the out side

Measurement Position Inside On Bend

3.

Tee Pieces Measurement position on head of T’1 in centre, 1 offset 900 each of “centre” Reading procedure D

Transfer straight pipe length

STRAIGHT PIPE LENGTHS 10 9

8

7 6 5 MI 18 4 3

2 1 VESSEL

ULTRASONIC VESSELWALL THICKNESS SURVEY Equipment description Tag no _______________Location __________ flow sheet no _______________ Nominal thickness (mm) Corrosion Allowance (mm) Minimum Acceptance thickness (mm) READING PROCEDURE E

11

12

10

1

9 8

2

7 3

6 5

4

Weld root scan – pipe over 8” – carry out weld root scans with sheave / compression probes as appropriate expected is report minimum thickness for 12 quadrants Reading Procedure END CAP (3) Reading to be taken (4) Measurement around the circumstance adjacent to the weld, 1 measurement at the end cap

ULTRASONIC INSPECTION REPORT PROJECT CLIENT LOCATION CONTRACTOR

REPORT NO. REQUEST NO. DATE OF TEST ACC. CRETERIA

PROCEDURE NO. CALIBRATION BLOCK WELD TYPE OTHER DETAILS COUPLANT PERSONNEL

MATERIAL SURFACE CONDITION EQUIPMENT TYPE SERIAL NO.

SENSITIVITY:

ANGEL

PROBE SR. NO. MFR SONATEST

FREQUENCY MHZ

PROBE SIZE

PRIMARY REF. LEVEL

TRANSFER CORRECTION

SCANNING LEVEL

TOTAL (dB)

COMMENTS:

EDEMAC SERVICES

CLIENT

NAME:……………………………

NAME:……………………….

NAME:……………………

DATE:…………………………….

DATE:………………………..

DATE:……………………..

SIGN:…………………………….

SIGN:…………………………

SIGN:………………………

8.0 ILLUSTRATION OF SCANNING TECHNIQUES

A.

TYPICAL “Y” (NODE) WELD BRANCH MEMBER

SCRIBE OR PUNCH MARK BEFORE FIT-UP

DETAILS “A” OR “B”

DETAIL “D”

DETAIL “B”

DETAILS “C” OR “D”

(A)

00 compression probe scan on parent metal to check for laminations and to verify wall thicknesses

(B)

Angle probe scan (minimum of 3 probes- 450, 600, 700) from weld cap to full skip distance plus weld cap width for coverage.

(C)

00 compression probe scan to check for fusion defects (when accessible)

NOTE:Sound beam to be maintained perpendicular to the weld axis while scanning

B

TYPICAL “Y” (NODE) WELD

DETAIL “A” DETAIL “B”

DETAIL “C”

DETAIL “D”

ALTERNATE DETAIL “D”

(A)

00 compression probe scan on parent metal to check for laminations and to verify wall thicknesses

(B)

Angle probe scan (minimum of 3 probes- 450, 600, 700) from weld cap to full skip distance plus weld cap width for coverage.

(C)

00 compression probe scan to check for fusion defects (when accessible)

NOTE:Sound beam to be maintained perpendicular to the weld axis while scanning

C.

SINGLE “V” BUTT WELD

(A)

00 compression probe scan on parent metal to check for laminations and to verify wall thicknesses

(B)

Angle probe scan (minimum of 3 probes- 450, 600, 700) from weld cap to full skip distance plus weld cap width for full coverage.

D.

DOUBLE “V” BUTT WELD

(A)

00 compression probe scan on parent metal to check for laminations and to verify wall thicknesses

(B)

Angle probe scan (minimum of 3 probes- 450, 600, 700) from weld cap to full skip distance plus weld cap width for full coverage.

E.

TYPICAL “T” WELD

(A)

00 compression probe scan on parent metal to check for laminations and to verify wall thicknesses

(B)

Angle probe scan (minimum of 3 probes- 450, 600, 700) from weld cap to full skip distance plus weld cap width for full coverage.

(C)

00 compression probe scan on face “X” to check for fusion defects (when accessible)

(D)

Additional angle probe scan (minimum of 2 probes) on face “X” when accessible