Title: Method and device for ultrasonic inspection

The invention relates to a method for ultrasonic inspection of a fillet weld. The invention further relates to a device for ultrasonic inspection of a fillet weld. The invention further relates to an inspection result.

Of fillet welds such as the circular welds of split T's and repair shells of gas lines, good ultrasonic manual inspection is hardly possible. It has been shown that only a part of the weld is inspectable, and that defects with a relevant size can hardly if at all be distinguished from small flaws acceptable per se.

It is an object of the invention to obviate at least one of these problems.

To this end, the invention provides a method for ultrasonic inspection of a fillet weld, the method comprising ultrasonic inspection with the aid of a first ultrasonic phased array probe.

The invention further provides a device for ultrasonic inspection of a fillet weld, wherein the device is provided with a first ultrasonic phased array probe. The invention further provides a first inspection result, such as a report, obtainable by means of a method according to the invention.

The invention will be illustrated with reference to the appended, non- limiting drawing, in which:

Fig. 1 shows dimension V of a reduced portion of the shell; Fig. 2 shows a basic sketch of a reference block;

Fig. 3 shows an estimation of the orientation of a 6 mm-high fusion defect; Fig. 4 shows the presence of a diffraction signal; Fig. 5 shows a diffraction signal over skip; Fig. 6 shows acceptance criteria; Fig. 7 shows a photograph of a pipe (left/bottom), which may be part of a pipeline, and a split T (right/top), connected with a fillet weld extending in a circumferential direction of the pipe;

Fig. 8 shows an example of a phased array presentation; Fig. 9 shows an example of a manufacturing drawing for a reference block

(20/22 mm);

Fig. 10 shows a position determination of an indication;

Fig. 11 shows an overview photograph of a 36"split T at an inspection location; Fig. 12 shows a scanning arrangement for phased array at an inspection location;

Fig. 13 shows inspection results RN 1 shell side;

Fig. 14 shows inspection results RN 1 pipe side;

Fig. 15 shows inspection results RN 1 indication 1; Fig. 16 shows inspection results RN 1 indication 2;

Fig. 17 shows inspection results RN 2 shell side;

Fig. 18 shows inspection results RN 2 pipe side;

Fig. 19 shows inspection results RN 2 indication 1 (geometric indication);

Fig. 20 shows inspection results RN 2 indication 2; Fig. 21 shows a position determination of an indication;

Fig. 22 shows an overview photograph of a 36"split T at an inspection location;

Fig. 23 shows a scanning arrangement for phased array at an inspection location; Fig. 24 shows a problem with a welding mask at an inspection location;

Fig. 25 shows inspection results RN 1 shell side;

Fig. 26 shows inspection results RNl pipe side;

Fig. 27 shows inspection results RN 2 shell side; and

Fig. 28 shows inspection results RN 2 pipe side. Paragraphs 1-13 contain inter alia a description of mechanized ultrasonic inspection of circular welds of split Ts and repair shells (carbon steel lines) by means of phased arrays, in exemplary embodiments according to the invention. This procedure holds for ultrasonic inspection of circular welds of split

Ts and repair shells, for pipe diameters ≥ 18", pipe wall thicknesses between 8 and 22 mm and shell thicknesses (if applicable the thickness of the reduced part) between 10 and 25 mm. However, a similar procedure may also be used for pipe diameters < 18", pipe wall thicknesses < 8 mm or > 22 mm, and/or shell thicknesses < 10 mm or > 25 mm. So, it will be clear that the procedure, as well as the similar procedures, is an example of a method for ultrasonic inspection of a fillet weld, wherein the method comprises ultrasonic inspection with the aid of a first ultrasonic phased array probe.

1. General introduction

Of the ultrasonic inspection with the aid of phased arrays, as described in this procedure, it has been determined that volumetric inspection is indeed possible. In addition, height determination of detected flaws is possible (to a limited extent) with this technique. It will be clear that such possibilities are not easy to recognize. Here, the fact comes in that it is generally known that a fillet weld has a location with respect to the pipe, and has a geometry, which differs much from a weld connecting two pipe parts which have a similar shape (i.e. with substantially the same diameter and wall thickness) in line with each other. The fillet weld will, for instance, be found as a connection between two pipe elements with mutually different diameters, such as for instance a repair shell with an inner diameter placed around the outer diameter of a pipe element, or a split T with an inner diameter placed around the outer diameter of a pipe element. In the field of ultrasonic inspection, it has been known for a long time that fillet welds, such as corner welds, are very difficult to inspect. The inspection preferably uses sector scans (pulse-echo technique).

An object of the inspection described in this procedure is detecting and locating weld flaws as well as determining the size (height) thereof. Detected indications are preferably judged as being relevant or not relevant. Relevant indications are preferably shown with both the length and the height of the indication. These relevant indications are judged as being acceptable or not acceptable with the aid of the applicable acceptance criteria. The inspection is preferably carried out with two identical linear phased array probes, which are placed opposite each other on both sides of the weld (one on the pipe surface and one on the surface of the shell). So, it will be clear that, in this example, the weld (i.e. de fillet weld) forms a connection between the pipe and the shell. It will be clear that, here, the pipe has a different outer dimension than the shell. A first pulse-echo sector scan can be carried out along a first part of a cross section of the fillet weld with the aid of a first of the two ultrasonic phased array probes, which are, in this example, positioned on the surface of the pipe. (It will be clear that the pipe is an example of a first pipe element). This can lead to a first scan result. In addition, a second pulse-echo sector scan can be carried out along a second part of the cross section of the fillet weld with the aid of a second of the two ultrasonic phased array probes, which is, in this example, positioned on the surface of the shell. (It will be clear that the shell is an example of a second pipe element). This can lead to a second scan result. The first and the second scan result can be analyzed for determining the presence or absence of a defect in the first and/or second part of the cross section.

The weld is inspected with the aid of a mechanical scanner, guided by means of a guide band to thus move the probes along the weld in one movement. A corner weld may be an example of a fillet weld. 2. NDO staff

2.1 The group leader, who carries out the inspection, may:

- have level 2-UT or an equivalent level, according to EN 473. - be additionally trained in the use and interpretation of the phased array system.

2.2 The assistant, who assists in the inspection, mav:

- have SKO level 1-UT or an equivalent level, according to EN 473.

- be trained in operating manipulators.

3. Equipment

3.1 Scanner

For the inspection, for instance, the RTD band scan is used. The scanner meets, for instance, the following requirements: • Guidance by means of a steel guide band provided on the pipe side next to the weld;

• Is capable of guiding at least 2 cardan-suspended phased array probes; distance to the weld individually adjustable;

• The scanner can bridge a height difference between the probes up to about 25 mm (this corresponds to the maximum (optionally reduced) shell thickness);

• Couplant supply per probe;

• Cable length between scanner and vehicle about 10 meters;

• The scanner is equipped with a position indicator, which measures the distance on the surface of the pipe;

• Maximum scanning speed 40 mm/sec.

3.2 Phased array probes

Two identical phased array probes with wedges can be used, with, for instance, the following properties: Type of array : Linear

Ultrasonic frequency : 10 MHz

Number of elements : 32

Element width : 7 mm

Pitch : 0.31 mm

The probe can be mounted on wedges with the following properties: Wedge material : Rexolite (CL = 2345 m/s)

Primary wedge angle : 35°

Probe building number : 07-1576 / 1577 or equivalent 3.3 Electronics

A phased array system with the following properties can be used:

Number of channels : Minimally 64 (suitable for connecting 2 probes with 32 elements each) Number of simultaneously : Minimally 32 active channels

Visualization by means of : Sector scan, from both sides software

The equipment can support the simultaneous carrying out of sector scans from two sides. In addition, pitch-catch mode can be supported (coupling check per probe, with a 0° angle).

In Fig. 8, an example of a sector scan recording is shown.

3.4 Check of equipment The equipment preferably complies with RTD check procedure CP-31111 "Calibration check procedure for ultrasonic phased array equipment", latest revision. 3.5. Calibration check of the encoder

A test scan can be carried out over a known length. The displacement shown on the display corresponds to the path travelled on the pipe surface, with a tolerance of approx. 2.5%.

It will be clear that, herewith, an example of a device for ultrasonic inspection of a fillet weld is described, wherein the device is provided with a first ultrasonic phased array probe.

4. Possible requirements to be imposed on the object to be inspected

4.1. Geometry / accessibility of the weld

The section of the end of the shell is shown in Fig. 1 for the case where a reduction is applied to the shell. In order to accommodate the probe, the length of the reduced part (dimension V in the Figure) is preferably at least 30 mm.

4.2. Couplant and surface condition

Water or antifreeze can be used to acoustically couple the probes with the shell and pipe surface, respectively, in an ambient / surface temperature of -15 to +40 ⁰ C. In winter time, with use of antifreeze, preferably, a receiving bin is used.

The couplant is fed via the probes, between the probes and the pipe surface.

In order to guarantee a good acoustic contact between the probes and the pipe material, the probing surface is, preferably, on both sides of the weld over a width of at least 75 mm, free from welding spatters, coating and/or other flaws which can disturb the coupling. Also, preferably, the longitudinal welds of both the pipe and the shell are ground smooth over a distance of at least 75 mm for the benefit of an undisturbed probe run. The sealing layer of the circular weld projecting above the split T is preferably also ground smooth for the benefit of an undisturbed probe run.

In case of a reduction, this distance is the length of the reduction and the adjoining radius.

5. Weld identification and coordinate system

The welds to be inspected may be provided with an unambiguous identification, which can be entered into the phased array system, so that it can be shown together with the measuring results. The X coordinate used by the system is the weld length from the zero point on top of the pipe or a reference point to be defined in more detail with vertical pipe connections. The direction of rotation (= positive X direction) is viewed clockwise in the flow direction of the gas. Exceptions can be recorded in the phased array system under "comments" and in the report.

6. Possible setting of the equipment 6.1. Basic settings

The equipment can be set as follows:

Number of simultaneously active : 32 for both probes elements

Sweeping range : 40 to 70° in steel for both probes

Angle increments : 2°

Averaging : Ix

Sampling frequency : 50 MHz

Frequency filters : Switched off

Gate start of probe on shell side : 10 mm from the point of entrance

Gate length of probe on shell side : 90 mm

Gate start of probe on pipe side : 10 mm from the point of entrance Gate length of probe on pipe side : 110 mm

Measuring point density : 2 mm on the circumference of the pipe Scan length : Circumference of pipe plus an overlap of 100 mm

6.1. Tools for sensitivity setting

The sensitivity setting can take place by means of a reference block according to Fig. 2. The working drawings for such reference blocks can be generated by an automatic module in Solid Edge, on the basis of given pipe and shell thicknesses.

Fig. 2 shows how the dimensions are chosen by the Solid Edge model on the basis of these data.

The "pipe thickness" and the "shell thickness" of the reference block to be used are preferably as close as possible to the pipe thickness and shell thickness of the component to be inspected. Deviations of at most plus or minus 5 mm are allowed.

For different thicknesses of pipe wall and shell, different reference blocks are available. If no reference block is available of which both the pipe thickness and the shell thickness are within the given tolerance, two blocks may be used (separately for setting of the probe on the shell and on the pipe side).

For all reference blocks, preferably the following agreements hold:

• A and E have a fixed value of 150 mm • The total height H is equal to P+S+2 mm, wherein S is the shell thickness (S does not occur in the above drawing)

• Bored holes are cylinder holes, diameter 2 mm, 120° apex angle, depth 25 mm

• Notches are made by means of spark erosion, width 1 mm, length 20 mm • Notch depth is 2 mm for pipe wall thicknesses < 15 mm, 2.5 mm for pipe wall thicknesses >15 mm, in accordance with the applicable acceptance criteria (see chapter 8)

• Notches are spaced over the width such that all interspaces are equal

• B + C + D = 2S

• B = 0.7 x S

• D = 0.4 x S

• C = approx. 1.0 x S (this is the balancing item and may deviate slightly)

Fig. 9 shows an example of a manufacturing drawing, as it is generated in this manner for a pipe thickness of 20 mm and a shell thickness of 22 mm.

6.2. Example of sensitivity setting and probe placement The sensitivity setting is derived from CSW-05-E "DGS method", provided that not a 2-mm flat bottom bore, but a 2-mm high notch is used as a reference reflector.

Probe setting on shell side:

• Determine the point of entrance of the probe at an angle of entrance of 50°.

• Determine the optimal position of the probe on the reference block (shell side). This position corresponds to the optimal irradiation of reflector X (Fig. 2) with the 50° beam over half skip.

• With a shell thickness of 16 mm, the front of the probe will then be at the location of the transition between shell and welding material • With thicker shells, the probe is placed further back to achieve optimal reflection at 50°; in case of limited space (when a reduction is present), this may not be feasible, but the probe is preferably placed as far back as is possible (therefore the probe is provided with an oblique side at the back)

• With thinner shells, the probe is placed further forwards. The allowable maximum distance over which the probe can be placed forwards ("overhang") is 7 mm. This is to ensure that the complete beam enters the material. • From the optimal position, the maximum reflection of notch X is set at 80% BSH + 6 dB. This value is referred to as H _r (reference amplitude).

• It is ensured that the bores are visible with this sensitivity. The amplitude is purely indicative. • After the calibration, the set sensitivity is documented by means of a calibration scan of the reference block with the respective probe.

• When the probe is built in in the scanner, the position of the probe is corrected for the difference in wall thickness between the reference block and the shell (the reduced thickness applies: forwards with a thinner shell, backwards with a thicker shell This is to ensure that defects of the type X are still optimally irradiated with the 50° beam. The correction c in mm is Δd * tg 50°, i.e. 1.2 * Δd, Δd being the difference in watt thickness in mm.

• Sensitivity correction is described later (transfer measurement).

• Correction for the differences in path of sound in the wedge for the different angles ("apodization") is not applied. Probe setting on pipe side:

• Determine the point of entrance of the probe at an angle of entrance of 50°. • Determine the optimal position of the probe on the reference block (pipe side). This position corresponds to the optimal irradiation of reflector Z (Fig. 2) with the 50° beam over full skip.

• With the thinnest pipe (8 mm), the probe will then abut the weld (if not, put it backwards as far as necessary), with larger thicknesses, it will be further backwards.

• From the final position, the maximum reflection of notch Z is set at 80% BSH + 12 dB. This value is referred to as H _r (reference amplitude). • It is ensured that the reflections of the bores are visible with this sensitivity. The amplitude is purely indicative.

• After the calibration, the set sensitivity is documented by means of a calibration scan of the reference block with the respective probe. • When the probe is built in in the scanner, the position of the probe is corrected for the difference in wall thickness between the reference block and the pipe: forwards with a thinner pipe (if possible), backwards with a thicker pipe. This is to ensure that defects of the type Z are still optimally irradiated with the 50° beam over skip. The correction c in mm is 2 * Δd * tg50°, i.e. 2.4 * Δd, Δd being the difference in pipe in mm.

• Sensitivity correction is described later (transfer measurement). • Correction for the differences in path of sound in the wedge for the different angles ("apodization") is not applied.

Sensitivity correction by means of transfer measurement: • Prior to building in the probes, a transfer measurement is carried out.

• Place the two probes opposite each other in their optimal position for the reference block.

• If for the sensitivity setting two different blocks are used, then choose for the transfer measurement the block of which the sum of the pipe thickness and shell thickness comes closest to the sum of the pipe thickness and shell thickness of the component to be inspected.

• Of both probes, the angle is varied to optimize the transfer signal (both angles do remain the same).

• Record the amplitude of the transfer signal (A).

• After building in the probe, the angle of both probes is again varied to optimize the transfer signal (both angles the same). Let the scanner run over a distance of e.g. 100 mm and record the average echo height (B).

• The difference between A and B is the transfer correction. This is applied to both probes.

Coupling check: On both probes, a perpendicular beam (0°) is set as a coupling check.

Alternatively, the irradiation (transfer) echo may be used.

7. Possible manner of carrying out the inspection

After the phased array system has been set and the probes have been built in, one may proceed as follows: • Provide the guide band, position the scanner on the pipe, where the zero point is, and check the probe distance and whether the probes abut well.

• Switch on the supply of the couplant. • Now switch on the system and have the weld scanned, at a speed of maximally 40 mm/sec, yet in any case not so fast that any data are missed.

• Scan the weld completely, with an overlap of 100 mm.

• If necessary, the scans may be made with both probes separately. • If the scan contains an indication with amplitude > 100% BSH, the scan is preferably scanned again with a lower sensitivity in order to be able to determine the height of the amplitude.

It will be clear that the scanning of the weld referred to in this example comprises moving the first phased array probe along the pipe surface and moving the second phased array probe along the shell surface, in a circumferential direction of the pipe, for scanning along a plurality of cross sections of the weld (i.e. the fillet weld). It will be clear that, in this example, the fillet weld forms a connection between the pipe and the shell.

8. Example of interpretation of the result

8.1. Purpose of the interpretation

The purpose of the interpretation is preferably twofold:

• determining the presence of relevant indications. • characterizing and determining the height of found defects.

Here, the measured height of any defect in millimeters is compared with that of the reference reflector (2 mm-high notch). Determining indications and height determination particularly take place at the following locations:

• Determine whether indications come or do not come from geometry.

• Non-geometric indications are relevant indications: they are preferably evaluated from an echo height of 20% BSH (after deduction of the scan sensitivity). 8.2. Possible characterization and sizing of indications on the fusion line between shell and weld It is determined:

• whether or not a diffraction signal from the flaw tip is obtained;

• what is approximately the orientation of the defect; • whether a small or large defect is involved.

The orientation is determined by ascertaining in what angle range the largest reflection takes place (defects of the sheD - weld fusion line). See Fig. 3 (in which a 6 mm-high defect is used as an example). With a flaw orientation at 0° (perpendicular to the surface), particularly the angle effect will prevail, received with angles around 45°. With a flaw orientation of about 45°, particularly the plane of the flaw will prevail;, also received with angles of around 45°, but over a smaller angle range (as a result of the directive efficiency of the mirroring flaw). A flaw oriented according to an angle halfway between 0 and 45° is particularly detected with angles in the higher range.

For a fusion defect between shell and weld, it holds that a small defect is present if it is concluded that it is oriented vertically, no diffraction signal is present and the geometry signal is not interrupted.

In such cases, for an approximation of the flaw height, the amplitude is used. An amplitude equal to the corresponding notch (X or Z) means a height of 2 mm. A smaller signal means a height of < 2 mm.

If a diffraction signal is obtained, it is preferably used to determine the height.

Fig. 4 gives an example of an angle effect signal (the second signal on the A image) combined with a diffraction signal (the first signal).

Preferably, it is attempted to measure the distance in time delay between the angle signal and the diffraction signal in the A image of one single angle. This increases the accuracy (different angles have different time delays in the wedge, which makes a combination of signals from different beams inaccurate). The flaw height is calculated from this time delay difference, divided by the cosine of the respective angle.

If a defect at the location of notch X is so large that its diffraction signal cannot be seen anymore, even not with the most level angle (70°), use can be made of a diffraction signal found over skip (the second signal in Fig. 5). 8.3. Characterization and sizing of indications on the pipe side (underbead crack)

Preferably it is determined:

• whether or not a diffraction signal from the flaw tip is obtained; • what is approximately the orientation of the defect;

• whether a small or large defect is involved.

For an underbead defect, it holds that a small defect is present if no diffraction signal is present and the defect is not found with the probe on the shell side (so on the other side). In such cases, for an approximation of the flaw height, the amplitude is used. An amplitude equal to the corresponding notch (Z) means a height of 2 mm. A smaller signal means a height of < 2 mm.

If a diffraction signal is obtained, this is preferably used to determine the height.

8.4. Length determination of defects

Length determination of defects is preferably done according to the amplitude half-value method. The amplitude half-value method is known per se to a skilled person, so that a further explanation thereof is deemed unnecessary.

9. Acceptance criteria

Acceptance criteria are preferably based on the applicable standard for the acceptability of weld flaws. Because the phased array inspection may have a flaw height as a result, and is, in this sense, similar to ToFD, the acceptance criteria are, for instance, identical to those for the ToFD inspection. The acceptance criteria for weld flaws are, for instance (see Fig. 6):

Defects of the type X, Y and Z are considered exiting. It may further hold that:

A group of indications, of which the individual indications are acceptable, is only acceptable provided that all following conditions are met: a) The distance between successive indications in longitudinal direction of the weld is larger than or equal to the average length of the indications. b) The distance between two successive indications in the thickness direction of the weld is larger than or equal to the height of the highest indication plus 50%. c) No two or more flaws situated above each other having a height of more than 1.5 mm each are present, irrespective of the position in width location of the weld. d) The sum of the length of the individual indications is smaller than or equal to 7 -ck measured over any length from % D to maximally 300 mm in longitudinal direction of the weld. Indications that do not meet the above conditions ad a), ad b) and ad c) are preferably treated as one indication. The defect dimensions ("h" and "l") can then be measured including the distance between the indications and the table can be used for the evaluation.

If flaw height determination with phased array is impossible, the following criteria can hold:

- Any reflection of more than 80% BSH is rejected at a length exceeding 10 mm, irrespective of location and position of the weld.

- If reflection values are between 40% and 80% BSH, the height of the indication is taken as being equal to hz and the allowable length is equal to /max, h3.

- If the reflection values are between 20% and 40% BSH, the indications are viewed as and the allowable length is equal to / _ma χ, hi.

- For the length determination, the amplitude half-value method is used.

Indications in the volume of the weld are reported with an amplitude > 20% BSH, when their length is > 10 mm.

10. Report

The results of the inspection can be reported in the format below. Relevant indications in a scan can be reported with their circumferential position on the pipe surface and their position in depth direction.

Ace. = acceptable; N. A. = non-acceptable; cbd = cannot be determined; geom. = geometric indication Further, the report preferably comprises:

• inspection date • names and qualifications of the inspectors

• equipment used

• weld number / zero point

• diameter

• wall thickness of pipe and shell

11. Example

Fig. 7 shows a photograph of a pipe (left/bottom), which may be part of a pipeline, and a split T (right/top), connected with a fillet weld extending in a circumferential direction of the pipe. It will hence be clear that the fillet weld forms a connection between a first pipe element (here: the pipe left/bottom) and a second pipe element (here: the split T right/top). Here, it can clearly be seen that the split T has a larger diameter than the pipeline, so that the weld connection forms the fillet weld, here a corner weld. In this example, a pipe part of the split T has a larger diameter near the fillet weld than a pipe part of the pipe near the fillet weld. The split T may, for instance, be considered a split T-section or a split sleeve, for instance for the purpose of a branch. It will be clear from Fig. 7 that, more generally, a dimension of the fillet weld, measured in a longitudinal direction of the first pipe element such as the pipe, decreases in a direction from an inside of the first pipe element towards, and perpendicular to, an outside of the first pipe element. So, parts of the fillet weld located further from the pipe extend less far along the pipe. In other words, the fillet weld becomes increasingly narrower in a direction from the inside of the pipe to the outside of the pipe. 12. Practical example: inspection of the circular welds of the

36" split T for the benefit of valve 1.

Summary of the results: During the phased array inspection of RN 1 and RN 2, one indication has been observed in RN 1 which leads to rejection of the weld; on the other hand, RN 2 is acceptable according to the procedure.

12.1 Reason

A pilot project has been started. The circular welds of the 36" split T are inspected with the aid of the phased array inspection.

The inspection is carried out with the ultrasonic phased array technique.

12.2 Inspection program

Inspection of the circular welds of the 36" split T for the benefit of valve 1 by means of phased array.

Deviations in research : No program

12.3 Mode of carrying out 12.3.1 Inspection procedure

Inspection procedure used : UT-07147, rev. 3 (draft)

Deviations from the procedure: : None

12.3.2 Object data

Type of object : Split T

Object identification : Line for the benefit of valve 1

Material : C-steel Shell wall thickness 20 mm

Pipe wall thickness 14 mm

Pipe diameter 36"

Surface temperature 15 ⁰ C.

Surface condition Brushed

Coating No

12.3.3 Equipment data and settings

Equipment used TD Focus Scan Registration : SN0069 no.

Calibration expiry date Software version TD-scan 17.00 Manipulator type Band scan Registration : 001 no.

Reference block P20-S22 Registration : P20-S22 no.

Shell sensitivity 80% BSH + 6 dB on notch X with 50° beam setting

Pipe sensitivity setting 80% BSH + 12 dB on notch Z with 50° beam

Couplant Water

Probe distance shell 24 mm side

Probe distance pipe 36 mm side

Frequency and 10 MHz - 32 Registration : 07-1577 elements of shell elements no.

Frequency and 10 MHz - 32 Registration : 07-1576 elements of pipe elements no. 12.3.4 Inspection locations

Both circular welds of the 36" split T have been inspected by means of phased array inspection. The longitudinal weld on the bottom side of the split T has been used as a zero point. The direction of scanning and numbering of the welds are shown in Figs. 11-20.

The photographs are added in Figs. 11 and 12. 12.4 Results

During the phased array inspection of RN 1 and RN 2, one indication has been observed in RN 1 which leads to rejection of the weld; on the other hand, RN 2 is acceptable according to the procedure.

The results of the inspection are included in the table below:

Ace. = acceptable; N.A. = non-acceptable; cbd = cannot be determined; geom. = geometric indication

The phased array scans have been printed and added in Figs. 13-20.

The shell on RN2 side is probably reduced on the inside. Therefore, this is judged as being a geometric indication. 12.5 Recommendation None 13. Practical Example: Inspection of the circular welds of the

30" split T for the benefit of valve 2.

Summary of the results: During the phased array inspection of RN 1 and RN 2, no indications have been observed which lead to rejection of the welds. Accordingly, both welds are acceptable according to the procedure

13.1 Reason

A Pilot project has been started. The circular welds of the 30" split T are inspected with the aid of the phased array inspection.

The inspection is carried out with the ultrasonic phased array technique.

13.2 Inspection program

Inspection of the circular welds of the 30" split T for the benefit of valve 2 by means of phased array.

Deviations in research : Yes, due to the welding mask projecting above program the reduction, the probe on the shell did not abut properly so that it was not covered 100% (see Fig.24).

13.3 Mode of carrying out 13.3.1 Inspection procedure

Inspection procedure used : UT-07147, rev. 3 (draft)

Deviations from the procedure: : None

13.3.2 Object data Type of object Split T Object identification Pipe for the benefit of valve 2 Material C-steel

Shell wall thickness 15 mm

Pipe wall thickness 18 mm

Pipe diameter 30"

Surface temperature 15 ⁰ C

Surface condition Brushed

Coating ^• No

13.3.3 Equipment data and settings

Equipment used TD Focus Scan Registration : SN0069 no.

Calibration expiry date Software version TD-scan 17.00 Manipulator type Band scan Registration : 001 no.

Reference block P20-S22 Registration : P20-S22 no.

Shell sensitivity 80% BSH + 6 dB on notch X with 50° beam setting

Pipe sensitivity setting 80% BSH + 12 dB on notch Z with 50° beam

Couplant Water

Probe distance shell 24 mm side

Probe distance pipe 36 mm side

Frequency and 10 MHz - 32 Registration : 07-1577 elements of shell elements no. Frequency and 10 MHz - 32 Registration : 07-1576 elements of pipe elements no.

13.3.4 Inspection locations

Both circular welds of the 30" split T have been inspected by means of phased array inspection. The longitudinal weld on the bottom side of the split T has been used as a zero point. The direction of scanning and numbering of the welds are shown in Figs. 22-28.

The photographs are added in Figs. 22-24 13.4 Results

During the phased array inspection of RN 1 and RN 2, no indications have been observed which lead to rejection of the welds. Accordingly, both welds are acceptable according to the procedure.

The results of the inspection are included in the table below:

Ace. = acceptable; N.A. = non-acceptable; cbd = cannot be determined; geom. = geometric indication

The phased array scans have been printed and added in Figs. 25-28. 13.5 Recommendation

In order to be able to completely inspect the weld from the shell side, in the future, if this is possible, the projecting weld layer which projects above the reduction is preferably removed (see Figs. 22-24).