Phasor XS Flange Face Paper

GENERAL ELECTRIC INSPECTION TECHNOLOGIES

Flange Face Corrosion

Inspection Using PHASOR-XS Inspection from the Bolting surface

WJ Perry

T Ballenger

2/17/2009

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Background:

In the current economic environment, there is increasing pressure on petrochemical

refineries and delivery systems to be more productive and to minimize unscheduled shutdowns

due to leakage. Leakage can occur from either the piping itself or the joints of the pipes. In a

refinery there are several thousands of feet of piping and associated joints, as shown in the

photograph presented in Figure 1. Petrochemical leaks don’t only cost the companies money for

the time and material to repair a leak, but also to remediate the areas affected and the institution

of stricter controls. Because of this pressure, the involved companies are looking to replace the

current monitoring scheme with a more effective and cost efficient risk based inspection (RBI)

program. The backbone of such a program is the concept of being able to quickly identify the

most serious conditions so that they can be attended to immediately, and conditions of lesser

concern can be relegated to remediation at a future shutdown.

One area where leakage is a concern is at the bolted flange joints. Each joint consists of

two mating flanges with a gasket material between them, Figure 2. Leakage at these joints is a

result of the corrosive material being transported in the lines attacking the steel flanges and

removing material from the sealing surfaces to such an extent that the seal is compromised and

leakage occurs. In the petrochemical refinery process, the Health , Environmental and Safety

(HES) concerns for some of the materials are quite severe, and therefore any leakage is of grave

concern,

The current monitoring philosophy relies heavily on the physical disassembly of the

joints to do a visual inspection of the surfaces. Due to the time involved to disassemble the

joints, perform the visual inspection and reassembly, a push has been put forth to supplement the

visual inspections with a non-invasive technique, such as ultrasonics. The approaches have

ranged from simple manual single element raster type inspection to complex phased array

scanner based systems. The single element approach provides simplicity in operation, but

complexity in analysis. A phased array scanner based system sacrifices simplicity in operation

for reduced data analysis complexity. Within the range of possible ultrasonic techniques, there

does not exist a simplistic manual phased array approach. To answer this need, GEIT has to

developed a solution utilizing the PHASOR –XS ®

in conjunction with manual manipulation of a

phased array probe. This solution provides the best of both worlds (i.e., ease of operation and

simplicity of data analysis)

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.

Discussion:

The evaluation of corrosion on the sealing surface of a flange can be accomplished from

three different surfaces (bolting surface, taper, and outside diameter of the flange). There is not

one that provides the perfect solution. Each one has drawbacks and advantages. The drawbacks

associated with scanning from the bolting surface includes areas that cannot be inspected

because of the bolt hole and studs, and also, this approach hinders an assessment of the actual

amount of material loss from the bolt surface, because of the angle of the beams impinging on

the surface of concern. An inspection from the taper region has the drawback that different

curved wedges need to be developed for each different taper condition, and if full coverage is

required then a custom low profile probe and wedge are needed to fit behind the studs. Also, the

tolerances on the taper parameters (e.g., length of taper, angle of taper, and length of straight

pipe length above the taper) is not tightly controlled from size to size or from one design to

another. From the outer diameter of the flange, the drawbacks are the need for an encoded

scanning device to maintain the proper probe position while rotating the probe around the

circumference of the flange. Also, if wall progression assessment is required, this technique

requires full RF waveform capture to generate a C-scan type image from which to assess that

progression. With the need for scanning mechanisms for this technique an inherent limitation to

its use is the proximity of the joints to one another. In certain locations the piping runs may be

such that a scanning mechanism cannot fit into the space envelop available. Even with the

limitations of the ultrasonic techniques, the petrochemical industry has been relying more and

more on it because of the additional information that is provided to help the owners minimize

their liabilities.

In an attempt to bridge the gap between the simplest conventional single element

approach and the more comprehensive, GEIT began a study designed to provide a viable phased

array flange face inspection solution that is highly portable, and simple to use for an experienced

phased array inspector. The approach was centered on utilizing the PHASOR-XS®

along with

both standard and custom designed wedges as the data acquisition platform, and the Rhythm

software solution for reporting and archiving the results. The development of a full solution (i.e.,

one that covers data acquisition, analysis, reporting and archival) is a benefit to a customer

because inspection can be performed in a logical fashion and the results are available for future

reference for planning purposes. Presented below is a brief discussion of the approach used to

inspect for flange face corrosion progression from the bolting surface. Because of the many

variables that need to be considered this paper will only address that approach, and future papers

will present the discussions for the other possible inspection scenarios ( taper inspection, and

outer diameter inspection).

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Inspection from Bolting Surface

The first approach discussed is the inspection from the bolting circle surface. In this

approach a transducer is placed on the flat bolting surface of the flange with the ultrasonic beam

directed toward the ID of the pipe section, Figure 3. The concept behind this inspection

technique is that the ultrasonic beam will insonify the sealing surface of the flange and thereby

be able to identify the presence of corrosion. One factor a facility owner needs to realize that

with this inspection technique there are going to be areas that cannot be inspected (i.e., where the

bolting studs are located).

As stated previously, one ultrasonic technique currently being used for this inspection

technique is a single element crystal probe. The main benefit to an owner of a plant to employ

this approach is its’ simplicity of operation and portability. However, the facility owner must

realize that with the operational ease come several limitations that need to be considered when it

is applied. One is that multiple wedge configurations need to be used because with a single

element probe no phasing of the inspection angle can be accomplished. Also, to obtain the type

of detail needed to provide the assessment, the size of the ultrasonic beam needs to be relatively

small. Therefore to cover the necessary area with a single element crystal, a raster type scan

needs to be employed. Employment of raster scanning can identify the areas of concern.

However, such a procedure is a time consuming approach which thereby limits the number of

areas that can be examined in a given time. Also, if the technique is being performed in a

manual mode, with no hard copy output being generated, it becomes the inspector’s

responsibility to monitor A-scan (time) traces to identify what are geometric signals, and

therefore non-relevant, Figures 4 and 5 and what signals are associated with corrosion, Figure 6.

These interpretations require extensive skill of the operator and knowledge of the position of the

transducer when the signals are generated.

The discussion presented above highlighted some of the problem areas associated with

using a single element probe to perform an inspection for flange face corrosion from the bolting

surface. The problems specifically associated with single element inspections can be overcome

by the use of phased array technology on this inspection. With phased array technology, the

concept of the inspection is the same as for the single element probe (i.e., probe placed on the

bolting surface between the studs and the beam is directed toward the pipe ID). However,

phased array technology provides the advantage that multiple inspection angles can be generated

at the same time. With the proper design and selection of the phased array probe and wedge, it is

possible to perform the same inspection that a single element probe does without the need to use

multiple wedges or a raster type scanning motion. In selecting the proper transducer/wedge

combination, the goal is to be able to insonify the entire seating surface area, as well as part of

the inside diameter (ID) of the pipe. To introduce this technique to the marketplace, GEIT has

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focused on a synergistic approach of taking the best of a single element inspection and

incorporating it with the best of a phased array solution. From the single element inspection

comes the ease of equipment operation and the portability of the equipment. From the phased

array side, the multiple simultaneous inspection angles, an image to evaluate and the lacking

scanning. Figure 7 shows that data acquisition platform that incorporates these features, the

PHASOR - XS®. The PHASOR –XS is a highly portable manual inspection system that

incorporates both a 16/64 phased array board and a conventional single element flaw detector.

In arriving at a potential solution to the problem of detecting flange face corrosion, GEIT

attempted to use as much standard product as possible, and supplement them with custom

designed products as needed. The phased array probe that GEIT selected as the starting point

was a 5 MHz 16 element array. The pitch between elements is 0.040 inch and the elevation of

elements is 0.39 inch. That makes the aperture approximately 0.63 inch x 0.39 inch when all 16

elements are fired. The overall dimensions of the probe and the wedge selected are

approximately 1.3 inches x 1.3 inches. The space envelop of this probe is such that it will fit

between the studs on all flanges that have a specified diameter of 4.0 inch or greater, as shown in

Figure 8. For flanges with a smaller specified diameter, a narrower width probe/wedge

configuration is required.

In the performance of this inspection with the PHASOR-XS the operator has at his

disposal a weld overlay software option that can be used to guide in the interpretation of the data.

The overlay software was not written specifically for this application, but it can be used to define

the extent of the sealing surface. This provides the inspector a quick visual reference to look for

the region of interest on the image. Prior to the start of an inspection cycle the operator can

easily set up all the parameter files that will be needed. The parameter files will be generated

using the geometric information about the flanges to be inspected, and the pertinent information

about the transducer and wedge combination to be used. The flange information is readily

available from many sources, while the probe/wedge information is supplied with the probe and

wedge when purchased. After the inspector has generated the parameter files and stored them on

the SD card, he is ready to begin the inspections. There are two basic types of inspections that

an operator may perform on a flange from the bolting surface, (Screening Inspection and

Progression Assessment) and each one will be discussed separately. Contained within each

discussion will be representative images of what the operator should expect to see on the display.

Since the images presented herein are from the relatively limited sample set available, they

cannot possibly cover the entire gamut of conditions that an inspector may encounter in the field.

However, an experienced inspector should be able to use the knowledge presented in this

document and assess actual field conditions. As the inspector obtains more field exposure his

knowledge base will grow, so that each successive inspection will become easier. At the start of

an inspection cycle the objective of the inspector should be to perform a quick screening to

assess the overall condition of the joints in the plant so that he can concentrate on the most

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severely degraded joints. Presented below is the technique that an inspector would use to

perform such a screening inspection using the PHASOR – XS.

1. Screening Inspection Technique

The first step the inspector needs to perform is to recall the parameter file for the joint to

be inspected. The designation of the file should be something like “ Flange ID-Pressure rating”

When the file has been recalled, the inspector shall verify the sweep angles are sufficient for the

inspection and also set the “Leg Length” to 1.0. Such a setting will give the inspector a

sufficient display to see the image of interest. With the Phasor operational, the inspector then

needs to couple the probe/wedge combination to the flange bolting surface. Depending on the

surface condition and temperature of the flange the operator may need to use different couplant.

Rough surfaces or high temperatures tend to require a thicker couplant than a smooth cool

surface. Placement of the probe should be such that the back of the probe is at the outer edge of

the flange. Such a position will provide the inspector with a display that shows the entire sealing

surface of the flange face as well as part of the ID of the pipe.

With the probe located in such a position, the inspector should see, for a non-corroded flange, a

display similar to the display shown in Figure 9. This image is obtained by inspecting a 4 inch

raised face flange that has not seen service, and therefore is known to be free of corrosion. The

key item the inspector should be looking for during the screening process is the connection of the

second leg reflection off the pipe ID to the corner trap signal of the flange ID. The existence of a

connected second leg reflection means that the sealing surface in close proximity to the flange ID

has not been either roughened up or had its geometry changed by corrosion. If either of those

conditions had occurred the reflection off of the sealing surface near the ID would be at such an

angle that a connected second leg reflection would not exist. The sealing surface of the flange

needs to be flat to generate a reflected signal which would strike the pipe wall close to the

intersection of the flange bore ID and the sealing surface. However, the ID bore of the

flange/pipe combination also needs to be somewhat roughened to generate reflections off the

facets that can then return to the probe. Because once the angle of the sector scan varies from

the ideal angle to generate the large corner trap signal, the only way for the sound to return to the

probe is to be reflected at off angles due to the rough texture of the reflecting surface. For a pipe

/ flange system in a fluid flowing environment erosion of the pipe wall is an inevitable condition

What an inspector could expect to see for a flange that is experiencing corrosion can be shown

by the image presented in Figure 10. Figure 10 is an inspection result for a 4 inch raised face

flange that has corrosion present. This figure clearly shows there is a break in the second leg

reflection. The amount of separation that occurs for the second leg reflection can help the

inspector estimate the severity of the corrosion for a given corrosive environment. The

knowledge of the corrosive environment the joint is experiencing is necessary when estimating

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corrosion severity because a small amount of corrosion in a CO2 environment, is not as severe as

if the piping system is transporting HF based material. An example of the image for a corroded

HF ALKY flange is seen in Figure 11, and Figure 12 shows an image of a severely corroded 2

inch flange. These two images provide an example of the range of conditions that an inspector

could expect to see in assessing whether corrosion has been initiated at a bolted joint. In

examining Figure 11, it appears to be quite similar to that shown in Figure 9 for a non-corroded

flange. On the surface that is true, however with a closer look at the two figures, the thing that is

noticed is that the second leg reflection signal in Figure 11 appears to have successive hot spots

that are separated very slightly with low amplitude areas. This is indicative of a roughened

surface. What happens for a roughened surface is that slight depressions and ridges tend to

disrupt the specular reflection off the sealing surface, and it is those disruptions that yield a

pattern of hot spots and low amplitude areas. Therefore when an inspector is performing an

examination in a facility where HF Alky is present he must be aware that the screening

inspection aspect of the job will require close scrutiny of the images to discern that pattern. If an

inspector sees an image similar to that shown in Figure 12 there should be no uncertainty that

corrosion has occurred in that joint and it is severe. The reason for making that statement is that

the second leg reflective signal is completely missing. The cause of such a condition is due to

the combination of the corrosion progressing significantly inboard for the Flange ID and the

change from a flat plane nature of the sealing surface into a severe convex geometry where the

ultrasound beam is scattered in all directions. With completion of this brief discussion on the

screening for corrosion for bolted flange geometry, the next area to be discussed is the technique

to estimate the progression of corrosion when inspecting from the bolting surface.

2. Corrosion Progression Estimation Technique

Once corrosion has been identified to be existent in a joint, the inspector then needs to perform

an assessment of its extent. Determining the extent of corrosion is important, because corrosion

can exist in a joint and that joint is still performing its function as long as the corrosion does not

progress to the gasket located between the flange faces. Once corrosion has reached the gasket

the seal of the joint has been compromised and leakage will occur. Therefore, it is necessary for

the inspector to identify during an inspection what joints are in jeopardy of leaking before the

next inspection cycle. With a Risk Based Inspection (RBI) program, the idea of generating an

estimate of corrosion progression is to group the degree of corrosion into discrete bins. Those

bins could be identified as: (a) Acceptable, (b) Marginal, and (c) Failed. An acceptable joint

would be one that has either none or very little corrosion and based on information available

presents no chance of leaking before the next outage, and in fact could if desired be excluded

from the next inspection cycle. A marginal condition is one that is felt, based on all available

information, has a significant probability of not leaking before the next shutdown, but must be

evaluated during the next shutdown. A failed joint is one that is either leaking at the present time

or has a high probability of leaking before the next scheduled shutdown. With all of the

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inspected flanges put into one of these three categories, the owner of the facility can schedule the

needed remediation for the current shutdown and plan for the next shutdown.

The discussion of how an inspector can perform an estimate of corrosion progression will be

presented below and utilize Figures 13-18. These figures will cover representative types of

examples an inspector may encounter in the field. The first conditions to be presented are ones

that experienced CO2 corrosion, and they will progress from the most severe case to the mildest,

Figures 13-16. Figures 17 and 18 present images for flanges that have experienced HF Alky

corrosion. The basic steps an inspector would follow to estimate corrosion progression using the

PHASOR-XS can be summarized as follows:

(a) Establish Measurement Zero Point

(b) Review Image for Corner Trap Like Indications

(c) Establish point where Face Related Signals return to a Plane Indicative of Nominal

Face.

For an inspector to assess progression of corrosion on a sealing surface, he first must identify a

datum plane from which to begin the measurements. With the weld overlay software in the

PHASOR, the inspector has a tool that can help identify the data plane from which to begin the

measurements. Contained within the parameter files for each flange size to be inspected should

be a description of the length of the sealing surface. When the parameter file is loaded the

inspector will see a horizontal magenta box on the display that is tied to a vertical line. That box

represents the extent of the gasket sealing surface, based on nominal flange dimensions. The

vertical line is the starting point of the sealing surface, which correspond to the flange bore and

pipe ID. The end of the box opposite of the vertical line corresponds to the end of the sealing

surface. Because of the geometry of the flange sealing surface for both raised face and ring type

flanges, a corner trap signal occurs when the ultrasonic beam impinges on it. In addition to the

end of the sealing surface, the beginning of the sealing surface can also provide a corner trap

signal, if it has not been eroded by the corrosion. The inspector can use this information to

establish a starting point for positioning the weld overlay box. The inspector would position the

box such that the end of the box lines up with the corner trap signal associated with the end of

the sealing surface and the vertical line associated with the start of the sealing surface should line

up with either the corner trap signal associated with the flange bore or the pipe ID. The corner

trap signal associated with the flange bore and the pipe ID will not agree if significant corrosion

has occurred. This is the case for the sectoral image shown in Figure 13A. If the pipe ID and

flange corner trap signal do not agree then the pipe ID should be used as the starting point for

any measurements because that is where the sealing surface should have been if not corroded.

Another feature of the PHASOR –XS display that the inspector can use to his advantage when

estimating corrosion progression is the ability to set the part thickness to the value corresponding

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to the thickness of the flange bolting surface, including the raised portion of the sealing surface.

In doing this the PHASOR –XS will establish a horizontal line that can be used as a datum plane

for identifying the location of the nominal flange face sealing surface. This is beneficial in

evaluating whether signals emanating from the seal region are associated with corrosion or

machining marks on a pristine flange face.

Once the inspector has set up the measurement range of interest, then the inspector needs to

closely review the image concentrating on that region. What the operator is looking for are

corner trap like signals that emanate from facets associated with the corroded surface. When a

surface corrodes it becomes populated with ridges and valleys where material loss has either

been accelerated of inhibited. These conditions will cause the ultrasonic beam to be

preferentially redirected back toward the probe, thereby causing localized hot spots in the

images. This is comparable to what happens when a crack, which has branches, is insonified by

an ultrasonic beam. Because the corrosion starts at the flange bore and progresses toward the

end of the sealing surface the inspector should begin looking near the ID location and then

progress toward the left of the image to identify the hot spots. Another factor the inspector can

use to help identify signals due to corrosion is that the signals may be displaced relative to the

data plane associated with a pristine flange face. The displacement of the hot spots should be

vertically upward since the material thickness is less than for a non-corroded flange. The degree

of movement upward will be dependent on the amount of material loss. However, because of the

interaction of the ultrasonic beams with the inspection geometry any estimate of actual material

loss associated with the upward displacement shown by the hot spots is unreliable. To obtain

such correlation would require an extensive data base of flanges inspected, then removed from

service for physical measurements. That extensive effort is not warranted if the goal is simply to

provide a sorting criterion for a risk based assessment.

Figure 13A provides a sectoral scan for a single location between two studs of a 2 inch 300#

raised face flange. This image clearly shows the existence of severe corrosion, which is

confirmed by the photograph of the area shown in Figure 13B. The severity of the corrosion is

evident because of the displacement of the flange bore corner trap and the pipe wall ID. The

inward shifting of the flange bore corner trap signal means that severe material loss has occurred

causing a widening of the bore of the flange. Examination of the image further shows the

evidence of a high amplitude return signal to the left of the bore signal. That signal is displaced

upward from the bore signal, indicative of a reflection off a corroded surface. Further to the left

of that signal is grouping of two high amplitude signals. These signals have returned to the plane

associated with the nominal flange face plane. With this case of corrosion, the inspector would

select the location where this group of two occurs as the end the corrosion. Therefore in this

case with the PHASOR, the inspector would select that spot as the end of the corrosion and place

the vertical line associated with “Cursor 1” there and place the vertical line associated with

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“Cursor 2 at the region identified as the pipe ID. The inspector would then select the

measurement parameter identified as “P1-2” to obtain the estimate of the corrosion progression.

As shown in Figure 13, the value of P1-2 yields an estimated progression of 0.399 inch. This

estimate agrees extremely well with a physical corrosion measurement of 0.395 inch. As stated

before, this was one location for the 2 inch raised face flange sample that was available. Listed

in Table 2 is a comparison of the PHASOR measured and physical measurements for all eight (8)

locations of this flange. This table shows reasonable agreement between the PHASOR and

actual, especially when the goal is to provide a sorting criterion for a customer.

The sectoral scan and photograph shown in Figures 13 A&B is representative of the most severe

cases that were available to GEIT for this effort. The severity of the corrosion decreases as the

progression is made from Figures 14 to 18. The last two examples of corrosion presented herein

are for flanges that have experienced an HF environment. The techniques the inspector would

use to estimate the corrosion progression for these cases are the same as for the example shown

for the severe corrosion of the 2 inch raised face flange. However, because the corrosion is less

severe, the inspector needs to take greater care in evaluating the data before a call is made. This

is similar to any inspection where as the indications of interest become more subtle, the

evaluation time increases accordingly. However, even with the increased evaluation time, the

customer will be saving significant time and money over either the conventional single element

techniques or the physical separation and visual inspection of the joints. Also, if time is of the

essence to complete the inspection of as many joints as possible, then additional analysts can be

employed to perform the data analysis off-line while the inspector continues to scan each flange

and acquire the data. Such a scenario is possible with the PHASOR because the data sets can be

stored on removable SD cards, and then the stored data can either be read into another PHASOR

for evaluation or into the Rhythm software platform for analysis, reporting and archiving of the

inspections performed during the shutdown. As with the 2 inch raised face flange, Tables 2

through 6 provide a comparison of PHASOR generated corrosion progression estimates and

physical measurements. As these tables show, there is an increased inaccuracy for the estimates

of corrosion progression for the flanges that have been exposed to the HF environment. The

reason for this is that the corrosion associated with HF alky is a more gradual erosion of the

surface as compared to the surfaces associated with CO2 corrosion. The morphology of the

surface for CO2 corrosion is extensive hills and valleys; whereas for HF alky corrosion, the

surfaces as characterized by gradual changes with occasional pockmarks. Even with the

decrement in the accuracy of the measurements, it is still possible to generate groups of

conditions from which a customer can assess the condition of his facility and act to remediate the

most severe conditions before they begin to leak. In fact for the CO2 corrosion it appears that the

estimates made with the PHASOR are slightly conservative and therefore benefits the customer.

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As a supplement to the tabular presentations, Figure 19 shows the correlation of the Phasor

measurements taken during this study and the physical measurements for the corroded

conditions. This figure shows the 95 % confidence band on the correlation line and the 95%

confidence bands on the individual measurements. The analysis of variance for the data shows a

standard deviation on the measurement uncertainty to be approximately 0.068 inch. This

translates into approximately a 95% confidence level that any measurement of the corrosion

progression front should be within 0.125”. This uncertainty is well within the value necessary

for an owner/inspection company to categorize the severity of the corrosion for RBI. Also, this

is for the combination of both CO2 corrosion and HF Alky. When the two types of corrosion

mechanisms are considered separately, the variability for the CO2 corrosion decreases slightly;

while the variability for the HF Alky data set increases slightly, Figures 20 and 21 respectively.

The respectively variability in the predictive aspects of the inspection can and will be reduced as

additional data is added to the data base. However, these additions are going to require an

interaction between the owners of the facilities and either the inspection companies performing

the inspections with the PHASOR or with the manufacturer (GEIT).

Conclusions:

The work documented herein has shown that the PHASOR-XS can be a valuable tool to aid an

owner of a facility that is concerned with the minimizing the amount of time their facility is

down due to leakage from bolted joints. The PHASOR-XS when used by a skilled operator, can

provide a rapid means of surveying vast numbers of flanges during a shutdown. The survey

process can quickly identify the existence of corrosion and also provides a means to categorize

the extent for a given joint. With this information, the owner can then prioritize the remediation

efforts to concentrate on the flanges of greatest concern during the immediate shutdown. Also,

with the ability of the PHASOR to generate images that can be stored for future retrieval, the

owner can proactively plan for the next shutdown. This will result in minimal unexpected results

and therefore a more efficient expense of manpower and financial considerations.

Even though this effort has demonstrated the ability of the PHASOR to perform the inspection, it

does not mean that future improvements in either the PHASOR or it implementation are not

needed. There is always room for improvement in both the equipment and the inspection

techniques. Those improvements are a result of the equipment being used in the field and the

inspectors relaying back what could be done to improve the process. Also, as more and more

experience is gained by the inspectors their confidence in the inspection and increase accuracy of

the calls made by them will be a natural occurrence. Also, to continue improvements, laboratory

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work needs to continue which takes the form of looking at any flanges removed from service to

correlate the ultrasonic measurements to reality, and to understand what is causing any

significant discrepancies between what the inspector thinks the flange conditions are and what is

found when they are removed from service. If these correlations and investigations do not occur

then improvements will not occur. Also, the inspection companies/ facility owners need to have

two way communications with the equipment manufacturers so that suggestion for

improvements and additional features in the equipment can be factored into any new products

intended for field use.

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.

Figure 1: Examples of Bolted Flanges in a Refinery

Figure 2: Illustration showing Flange/Gasket Configuration.

Bolting Surface

Raised Face Corrosion

Gasket

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Figure 3: Illustration Showing Probe Location and Sound Field.

Figure 4 A-Scan Trace Showing Geometric Non-Relevant Seal Surface Corner Trap Signal

Pipe ID

Array

Sound Field Seal

Surface

Bolting Ring

Corner Trap Signal from Raised

Face Sealing Surface

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Figure 5 A-Scan Trace Showing Geometric Non-Relevant ID Surface Corner Trap Signal

Figure 6 A-Scan Trace Showing Geometric Relevant Signals Off Corrosion Facets

Corner Trap Signal from ID

of Flange

Reflected Signals Off

Facets of Corrosion

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Figure 7: GEIT – PHASOR XS and Probe

Figure 8: 5 MHz Array Probe Sitting on 4 Inch Flange

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Figure 9: Screening Inspection Image for Non Corroded Flange

Corner Trap Signal off

Flange ID

Second Leg Reflection

off Pipe ID

Pip

e ID

Dat

um

Graphic Overlay Box Highlighting

Sealing Surface

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Figure 10 Screening Inspection Image for Corroded Flange


Sealing Surface

Pip

e ID

Dat

um

Corner Trap Signal off

Flange ID


off Pipe ID (note faceted

nature)

Missing Reflection

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Figure 11 : Example of Screening image for an HF Alky Corroded Flange


Sealing Surface

Pip

e ID

Dat

um


off Pipe ID (note faceted

nature)

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Figure 12 : Example of Image from Severely Corroded 2 In. Flange

NO SECOND

LEG

REFLECTION

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Figure 13A: Phasor Image from a 2” Corroded Raised Face Flange

Figure 13B: Photo Showing Corroded Area of 2” Raised Face Flange

Corrosion Sealing Surface

Corrosion Extent

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Figure 14A: Phasor Image from a 3” Corroded Ring Flange

Figure 14B: Photo Showing Corroded Area of 3” Ring Flange

Sealing surface

Corrosion

Corrosion Extent

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Corrosion

Sealing Surface

Corrosion Extent

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Corrosion

Sealing Surface

Corrosion Extent

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Figure 17A: Phasor Image from a 2” Corroded Raised Face Flange (HF Alky)

Figure 17B: Photo Showing Corroded Area of 2” Raised Face Flange (HF Alky)

Sealing Surface Corrosion

Corrosion Extent

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Figure 18A: Phasor Image from a 6” Corroded Raised Face Flange (HF Alky)

Figure 18B: Photo Showing Corroded Area of 6” Raised Face Flange (HF Alky)

Sealing Surface Major Corrosion

Region

Minor Corrosion

Region

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Figure 19 : Comparison of Phasor Determined Progressions versus Physical Measurements

(Combined Data Sets)


(CO2 Data Sets)

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(HF ALKY Data Sets)

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Table 1: 2 IN Raised Face flange

Location Phasor Actual

Delta

(P – A)

1 .450 .454 -0.004

2 .444 .441 0.003

3 .407 .343 0.064

4 .434 .316 0.118

5 .420 .381 0.039

6 .440 .479 -0.039

7 .487 .476 0.011

8 .460 .476 -0.016

Table 2: 3” Ring Flange

Location Phasor Actual Delta

1 .464 .441 .023

2 .446 .440 .006

3 .495 .440 .055

4 .465 .440 .025

5 .437 .437 .000

6 .403 .395 .008

7 .433 .414 .019

8 .446 .433 .013

Page | 30

Table 3: 4” Raised Face Flange


1 .423 .414 .009

2 .440 .356 .084

3 .472 .473 -.001

4 .493 .453 .040

5 .500 .486 .014

6 .468 .456 .013

7 .447 .449 .002

8 .479 .464 .015

Table 4 6 IN Raised Face Flange


1 .756 .764 -.008

2 .664 .683 -.019

3 .784 .767 .017

4 .761 .767 -.006

5 .997 .812 .185

6 .816 .823 -.007

7 .686 .686 .000

8 .719 .762 -.043

9 .902 .902 .000

10 .668 .774 -.106

11 .728 .734 -.006

12 .742 .668 .074

Page | 31

Table 5 2 IN Raised Face Flange (HF Alky Exposure)


1 .517 .507 .010

2 .390 .660 -.270

3 .474 .490 -.016

4 .364 .347 .017

5 .384 .457 -.073

6 .460 .552 -.092

7 .460 .481 -.021

8 .464 .438 .026

Table 6: 6 IN Raised Face Flange (HF Alky Exposure)


1 1.058 .858 0.2

2 .933 .896 .037

3 .848 .896 -.048

4 .929 .996 -.037

5 .955 1.018 -.063

6 1.000 1.000 .000

7 .897 1.010 -.113

8 .991 .979 .012

9 1.040 1.055 -.015

10 1.116 1.020 .096

11 1.094 1.020 .074

12 .973 .921 .052

Page | 32

Phasor XS Flange Face Paper

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