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01:11 Nov-13-2008
Nathan (Recently passed 3.1 3.2)
Calibration for stainless steel.

Hi Guys.

How would I go about calibrating for testing stainless steel or duple welds? Obvioulsy beam angle would change due to the differing velocities, as would measurements etc.

Would I need to calibrate to an A1 block made of stainless steel?

Also, using the D.A.C. Method, would I need to create my own D.A.C. Curves using a stainless D.A.C. Block?

Confused..


 
03:12 Nov-13-2008
tj
Re: Calibration for stainless steel. ----------- Start Original Message -----------
: Hi Guys.
: How would I go about calibrating for testing stainless steel or duple welds? Obvioulsy beam angle would change due to the differing velocities, as would measurements etc.
: Would I need to calibrate to an A1 block made of stainless steel?
: Also, using the D.A.C. Method, would I need to create my own D.A.C. Curves using a stainless D.A.C. Block?
: Confused..
------------ End Original Message ------------

What are you normally testing. Velocity changes do not necessitate angle changes. If you are working to written procedure then it should call out calibration standard specs. You will more than likely need to calibrate to same material. You should not need a seperate block to establish DAC. If you have proper calibration standard you can use its reflectors.



 
03:36 Nov-13-2008

J. Mark Davis

Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama,
USA,
Joined Mar 2000
83
Re: Calibration for stainless steel. Dear Confused,

With coarse grain SS materials, you will need to use refracted Long waves to permit adequate penetration of the sound beam into the weldment. Ideally, you would fabricate a welded joint and place SDHs into the weld volume at 1/4 t, 1/2 t and 3/4 t. In addition, a 10% ID notch would be placed on one side of the weld near the toe of the weld in the HAZ area.

One thing to do would be to determine the grain size of the SS material. As the grain sizes approach a 1 or an O, or a double O (OO) (larger grain size), a refracted L-wave is the only way to inspect into and through the Weldment due to the dendritic weld structure.

With using L-waves you may need to grind the weld cap flush to achieve code weld volume inspection , since you can not bounce L-waves.

Another thought is to use phased arrays with refracted L-waves. The imagery that you would observe may aid in discrimination of noise signals versus defect signals.

For probe prequency, you are probably looking at using 1 to 2 MHZ depending grainin size.

Sincerely,

J. Mark Davis
University of Ultrasonics (TM)


----------- Start Original Message -----------
: : Hi Guys.
: : How would I go about calibrating for testing stainless steel or duple welds? Obvioulsy beam angle would change due to the differing velocities, as would measurements etc.
: : Would I need to calibrate to an A1 block made of stainless steel?
: : Also, using the D.A.C. Method, would I need to create my own D.A.C. Curves using a stainless D.A.C. Block?
: : Confused..
: What are you normally testing. Velocity changes do not necessitate angle changes. If you are working to written procedure then it should call out calibration standard specs. You will more than likely need to calibrate to same material. You should not need a seperate block to establish DAC. If you have proper calibration standard you can use its reflectors.
------------ End Original Message ------------




 
04:02 Nov-13-2008
Nathan
Re: Calibration for stainless steel. So, it's not a simple thing to flaw detect for stainless steel?


 
04:15 Nov-13-2008
tj
Re: Calibration for stainless steel. ----------- Start Original Message -----------
: So, it's not a simple thing to flaw detect for stainless steel?
------------ End Original Message ------------

Yes it should be just as simple as anything else. Are you testing pipe or plate? The other poster was talking casting I believe. What spec are you working to?


 
04:58 Nov-13-2008
Nathan
Re: Calibration for stainless steel. It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.


 
05:33 Nov-13-2008
tj
Re: Calibration for stainless steel. ----------- Start Original Message -----------
: It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.
------------ End Original Message ------------

Have a look at ASTM Section 3 E213 for your pipe (will work fine for stainless). This gives a description of cal standards. Will work for immersion or contact.


 
06:59 Nov-13-2008

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Re: Calibration for stainless steel. Congratulations on your exam success and qualification Nathan. Also you have been resourceful coming here to keep up with "continuous learning". Ask any long-time NDT hand and they will all tell you the same - in NDT you never stop learning, so it pays to be able to talk with co-workers with the same interests.

If your procedure is based on EN 1714, then you must be checking welds. Heed the advice from Mark and your technique will be reasonable. You could look up some papers on this site - J A Ogilvie did a great paper in the early 80's which clearly showed through ray-tracing, the bending effect on the beam of the long (through-thickness direction) as-cast columnar weld grains, as well as the noise due to beam scatter. Degree of bending varied with angle of incidence relative to the columnar structure. Forged stainless steel is fine equi-axed grains, so sound passes through without any bending effect and sidewall lack of fusion should be relatively easy to detect and evaluate. As Mark stated its the weld volume defects that are awkward thus low frequency, longitudinal wave for longer wavelength less affected by the grain structure. I dont know if there are any specially formulated weld procedures to minimise vertical grain growth to reduce ray-bending effect.

Radiography suffers from similar problem with stainless welds, the "herringbone" diffraction effect. This is countered by increasing kV.

Cheers

Nigel


----------- Start Original Message -----------
: : It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.
: Have a look at ASTM Section 3 E213 for your pipe (will work fine for stainless). This gives a description of cal standards. Will work for immersion or contact.
------------ End Original Message ------------




 
09:46 Nov-13-2008

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1185
Re: Calibration for stainless steel. Nathan, the suggestion by Nigel to look up some papers on the topic is a good one. In addition to Dr. Oglivie’s papers (on of which is J. A. Ogilvy; Ultrasonic beam profiles and beam propagation in an austenitic weld using a theoretical ray tracing model; Ultrasonics, Volume 24 Number 6 (1986), pp 337-347) I would recommend a Handbook. The Handbook on the Ultrasonic Examination of Austenitic Clad Seel Components, Compiled by Commission V of the IIW, Published by European Commission Joint Research Centre Institute of Advanced Materials, 1994.

Prof. (Dr?) Mark Davis from University of Ultrasonics ™ made a statement concerning grain sizes that is perhaps not clear to some. The reference to size based on ratings such as 00, 0, 1, etc. comes from an ASTM Standard. Grain size can range from 00 to 14.0 equates to 0.5080 to 0.0028 mm according to ASTM E112. Another good reference you might like to acquire is a book called Basic Metallurgy for Nondestructive Testing, edited by J. Taylor, and published by theBritish Institute of NDT 1996.

In chapter 5 Taylor makes note of the effect of anisotropy. In a cold worked form, such as thin plate and tubing might be, stainless grains would be well broken and approximately the same size in every direction. The result is acoustic properties are nominally the same in every direction (i.e. isotropic). But when welding occurs, the temperature rises and grain growth may result. Acoustic velocities along the long axis of the austenite columnar grain axes are slower and reach a maximum velocity at about 45° to the long axis. Heat dissipation directions in welding will determine the direction of grain growth. The result on the ultrasonic wavefront is to skew the beam towards the direction of maximum velocity.

Grain sizes at the weld and HAZ may therefore be quite large compared to the parent metal. In the Krautkramer text (Ultrasonic Testing of Materials) it is noted that at grain sizes up to about one one-hundredth of a wavelength scatter may be considered negligible. . Austenitic grains at 200microns (0.2mm) may not be uncommon in some weld regions. This represents 25% of the wavelength size for a 4MHz transverse mode! This is a much larger fraction than one one-hundredth of a wavelength so scatter will be a dominant factor. The scatter is due to the accumulated variation in acoustic impedances at the grain boundaries.

Sorry about the long lecture, but you asked about the calibration so I thought the background was necessary. The A1 block in stainless might be able to match the velocities in your pipe parent metal (but large variations could occur for either compressional or transverse modes). That would allow you to calibrate timebase and discover the new refracted angles that result (compared to the indicated values marked for carbon steel). But the bending effects of anisotropy and attenuation compensations will be much more difficult if the grain structure in the weld and HAZ are coarse. This may require a special block with an actual sample of the weld and agreed-upon targets.


----------- Start Original Message -----------
: Congratulations on your exam success and qualification Nathan. Also you have been resourceful coming here to keep up with "continuous learning". Ask any long-time NDT hand and they will all tell you the same - in NDT you never stop learning, so it pays to be able to talk with co-workers with the same interests.
: If your procedure is based on EN 1714, then you must be checking welds. Heed the advice from Mark and your technique will be reasonable. You could look up some papers on this site - J A Ogilvie did a great paper in the early 80's which clearly showed through ray-tracing, the bending effect on the beam of the long (through-thickness direction) as-cast columnar weld grains, as well as the noise due to beam scatter. Degree of bending varied with angle of incidence relative to the columnar structure. Forged stainless steel is fine equi-axed grains, so sound passes through without any bending effect and sidewall lack of fusion should be relatively easy to detect and evaluate. As Mark stated its the weld volume defects that are awkward thus low frequency, longitudinal wave for longer wavelength less affected by the grain structure. I dont know if there are any specially formulated weld procedures to minimise vertical grain growth to reduce ray-bending effect.
: Radiography suffers from similar problem with stainless welds, the "herringbone" diffraction effect. This is countered by increasing kV.
: Cheers
: Nigel
:
: : : It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.
: : Have a look at ASTM Section 3 E213 for your pipe (will work fine for stainless). This gives a description of cal standards. Will work for immersion or contact.
------------ End Original Message ------------




 
09:24 Nov-14-2008

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
782
Re: Calibration for stainless steel. Dear Nathan,

Congratulations for your success in exams and it is good that you are continuing the learning. While it would certainly be beneficial to check out the various published papers, it would also be practical to prepare specific standards for the material that you are trying to test. One of the most basic requirement of NDT is that as far as possible, the test standard (calibration block) should represent the material being tested. And if UT of plates, tubes/pipes is involved, I will be happy to help you since I worked in an organisation where tonnage quantities of austenitic stainless steel is routinely tested to various international standards.

With best wishes,

Swamy
Retired from Nuclear Fuel Complex

---------- Start Original Message -----------
: Nathan, the suggestion by Nigel to look up some papers on the topic is a good one. In addition to Dr. Oglivie’s papers (on of which is J. A. Ogilvy; Ultrasonic beam profiles and beam propagation in an austenitic weld using a theoreticalray tracing model; Ultrasonics, Volume 24 Number 6 (1986), pp 337-347) I would recommend a Handbook. The Handbook on the Ultrasonic Examination of Austenitic Clad Seel Components, Compiled by Commission V of the IIW, Published by European Commission Joint Research Centre Institute of Advanced Materials, 1994.
: Prof. (Dr?) Mark Davis from University of Ultrasonics ™ made a statement concerning grain sizes that is perhaps not clear to some. The reference to size based on ratings such as 00, 0, 1, etc. comes from an ASTM Standard. Grain size can range from 00 to 14.0 equates to 0.5080 to 0.0028 mm according to ASTM E112. Another good reference you might like to acquire is a book called Basic Metallurgy for Nondestructive Testing, edited by J. Taylor, and published by the British Institute of NDT 1996.
: In chapter 5 Taylor makes note of the effect of anisotropy. In a cold worked form, such as thin plate and tubing might be, stainless grains would be well broken and approximately the same size in every direction. The result is acoustic properties are nominally the same in every direction (i.e. isotropic). But when welding occurs, the temperature rises and grain growth may result. Acoustic velocities along the long axis of the austenite columnar grain axes are slower and reach a maximum velocity at about 45° to the long axis. Heat dissipation directions in welding will determine the direction of grain growth. The result on the ultrasonic wavefront is to skew the beam towards the direction of maximum velocity.
: Grain sizes at the weld and HAZ may therefore be quite large compared to the parent metal. In the Krautkramer text (Ultrasonic Testing of Materials) it is noted that at grain sizes up to about one one-hundredth of a wavelength scatter may be considered negligible. . Austenitic grains at 200microns (0.2mm) may not be uncommon in some weld regions. This represents 25% of the wavelength size for a 4MHz transverse mode! This is a much larger fraction than one one-hundredth of a wavelengthso scatter will be a dominant factor. The scatter is due to the accumulated variation in acoustic impedances at the grain boundaries.
: Sorry about the long lecture, but you asked about the calibration so I thought the background was necessary. The A1 block in stainless might be able to match the velocities in your pipe parent metal (but large variations could occur for either compressional or transverse modes). That would allow you to calibrate timebase and discover the new refracted angles that result (compared to the indicated values marked for carbon steel). But the bending effects of anisotropy and attenuation compensations will be much more difficult if the grain structure in the weld and HAZ are coarse. This may require a special block with an actual sample of the weld and agreed-upon targets.
:
: : Congratulations on your exam success and qualification Nathan. Also you have been resourceful coming here to keep up with "continuous learning". Ask any long-time NDT hand and they will all tell you the same - in NDT you never stop learning, so it pays to be able to talk with co-workers with the same interests.
: : If your procedure is based on EN 1714, then you must be checking welds. Heed the advice from Mark and your technique will be reasonable. You could look up some papers on this site - J A Ogilvie did a great paper in the early 80's which clearly showed through ray-tracing, the bending effect on the beam of the long (through-thickness direction) as-cast columnar weld grains, as well as the noise due to beam scatter. Degree of bending varied with angle of incidence relative to the columnar structure. Forged stainless steel is fine equi-axed grains, so sound passes through without any bending effect and sidewall lack of fusion should be relatively easy to detect and evaluate. As Mark stated its the weld volume defects that are awkward thus low frequency, longitudinal wave for longer wavelength less affected by the grain structure. I dont know if there are any specially formulated weld procedures to minimise vertical grain growth to reduce ray-bending effect.
: : Radiography suffers from similar problem with stainless welds, the "herringbone" diffraction effect. This is countered by increasing kV.
: : Cheers
: : Nigel
: :
: : : : It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.
: : : Have a look at ASTM Section 3 E213 for your pipe (will work fine for stainless). This gives a description of cal standards. Will work for immersion or contact.
------------ End Original Message ------------




 
01:11 Nov-18-2008
Nathan
Re: Calibration for stainless steel. Thanks for your encouragement guys. I know a lot of people get their tickets and don't respect them and are just happy to rush through their work and not care about it. I'm a bit different in that respect, I've always believed the old "if a jobs worth doing, it's worth doing right."

Anyway, what the plan is so far, and please, please, stop me if i'm wrong, we're going to purchase an A5, V1 and DAC blocks in both Carbon Steel and Stainless Steel. That way, I will be able to calibrate my probes. Draw up their beam spreads. And adjust them for DAC. I believe we will be using a sensitivity of DAC+14db.

I will only be testing Carbon and Stainless Steel pipe up to 12".

What is the acoustic velocity of 316SS? Shear and Compression?

----------- Start Original Message -----------
: Dear Nathan,
: Congratulations for your success in exams and it is good that you are continuing the learning. While it would certainly be beneficial to check out the various published papers, it would also be practical to prepare specific standards for the material that you are trying to test. One of the most basic requirement of NDT is that as far as possible, the test standard (calibration block) should represent the material being tested. And if UT of plates, tubes/pipes is involved, I will be happy to help you since I worked in an organisation where tonnage quantities of austenitic stainless steel is routinely tested to various international standards.
: With best wishes,
: Swamy
: Retired from Nuclear Fuel Complex
: ---------- Start Original Message -----------
: : Nathan, the suggestion by Nigel to look up some papers on the topic is a good one. In addition to Dr. Oglivie’s papers (on of which is J. A. Ogilvy; Ultrasonic beam profiles and beam propagation in an austenitic weld using a theoretical ray tracing model; Ultrasonics, Volume 24 Number 6 (1986), pp 337-347) I would recommend a Handbook. The Handbook on the Ultrasonic Examination of Austenitic Clad Seel Components, Compiled by Commission V of the IIW, Published by European Commission Joint Research Centre Institute of Advanced Materials, 1994.
: : Prof. (Dr?) Mark Davis from University of Ultrasonics ™ made a statement concerning grain sizes that is perhaps not clear to some. The reference to size based on ratings such as 00, 0, 1, etc. comes from an ASTM Standard. Grain size can range from 00 to 14.0 equates to 0.5080 to 0.0028 mm according to ASTM E112. Another good reference you might like to acquire is a book called Basic Metallurgy for Nondestructive Testing, edited by J. Taylor, and published by the British Institute of NDT 1996.
: : In chapter 5 Taylor makes note of the effect of anisotropy. In a cold worked form, such as thin plate and tubing might be, stainless grains would be well broken and approximately the same size in every direction. The result is acoustic properties are nominally the same in every direction (i.e. isotropic). But when welding occurs, the temperature rises and grain growth may result. Acoustic velocities along the long axis of the austenite columnar grain axes are slower and reach a maximum velocity at about 45° to the long axis. Heat dissipation directions in welding will determine the direction of grain growth. The result on the ultrasonic wavefront is to skew the beam towards the direction of maximum velocity.
: : Grain sizes at the weld and HAZ may therefore be quite large compared to the parent metal. In the Krautkramer text (Ultrasonic Testing of Materials) it is noted that at grain sizes up to about one one-hundredth of a wavelength scatter may be considered negligible. . Austenitic grains at 200microns (0.2mm) may not be uncommon in some weld regions. This represents 25% of the wavelength size for a 4MHz transverse mode! This is a much larger fraction than one one-hundredth of a wavelength so scatter will be a dominant factor. The scatter is due to the accumulated variation in acoustic impedances at the grain boundaries.
: : Sorry about the long lecture, but you asked about the calibration so I thought the background was necessary. The A1 block in stainless might be able to match the velocities in your pipe parent metal (but large variations could occur for either compressional or transverse modes). That would allow you to calibrate timebase and discover the new refracted angles that result (compared to the indicated values marked for carbon steel). But the bending effects of anisotropy and attenuation compensations will be much more difficult if the grain structure in the weld and HAZ are coarse. This may require a special block with an actual sample of the weld and agreed-upon targets.
: :
: : : Congratulations on your exam success and qualification Nathan. Also you have been resourceful coming here to keep up with "continuous learning". Ask any long-time NDT hand and they will all tell you the same - in NDT you never stop learning, so it pays to be able to talk with co-workers with the same interests.
: : : If your procedure is based on EN 1714, then you must be checkingwelds. Heed the advice from Mark and your technique will be reasonable. You could look up some papers on this site - J A Ogilvie did a great paper in the early 80's which clearly showed through ray-tracing, the bending effect on the beam of the long (through-thickness direction) as-cast columnar weld grains, as well as the noise due to beam scatter. Degree of bending varied with angle of incidence relative to the columnar structure. Forged stainless steel is fine equi-axed grains, so sound passes through without any bending effect and sidewall lack of fusion should be relatively easy to detect and evaluate. As Mark stated its the weld volume defects that are awkward thus low frequency, longitudinal wave for longer wavelength less affected by the grain structure. I dont know if there are any specially formulated weld procedures to minimise vertical grain growth to reduce ray-bending effect.
: : : Radiography suffers from similar problem with stainless welds, the "herringbone" diffraction effect. This is countered by increasing kV.
: : : Cheers
: : : Nigel
: : :
: : : : : It would most probably be pipe. Although, i wouldn't have thought it would vary much for plate. We have our own spec, although, it follows BS EN 1714 1998 closely.
: : : : Have a look at ASTM Section 3 E213 for your pipe (will work fine for stainless). This gives a description of cal standards. Will work for immersion or contact.
------------ End Original Message ------------




 
02:41 Nov-18-2008
tj
Re: Calibration for stainless steel. Here is a link to velocity tables.




 
02:43 Nov-18-2008
tj
Re: Calibration for stainless steel. ----------- Start Original Message -----------
: Here is a link to velocity tables.
------------ End Original Message ------------

http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Reference%20Information/UT/ut_matlprop_metals.htm


 
08:01 Nov-18-2008

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Re: Calibration for stainless steel. Nathan

Doesnt your organisation employ an UT level 3 or retain outside level 3 services? For apparently non-routine tasks such as austenitic weld inspection, s/he should have compiled an appropriate procedure and devised a detailed instruction sheet. As Swamy indicated a welded sample containing artfully-positioned defects, preferably natural but artificial would do, should be available for operator familiarisation with the inspection characteristics..

Newly-qualified people should be mentored through their initial experiences, not slung in at the deep end and left to sink or swim. Now for your sake I hope thats not the case Nathan, but you havent made any mention of guidance from within your company so far.

And I am a little worried that you are skating over the surface by acquiring stainless blocks and then thinking thats OK now. Mark Davis showed you need to clarify if you have the right equipment for the job amongst other things.

Good luck



 
08:37 Nov-18-2008
tj
Re: Calibration for stainless steel. ----------- Start Original Message -----------
Nathan

I would have to agree with Nigel. If a technique must be made up for a job it is usually approved by a level 3 who has experience with the application. Letting mangement know that you are not sure about developing this technique is the right thing to do. They should know this already.



 
06:48 Nov-19-2008

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
782
Re: Calibration for stainless steel. Dear Nathan,

Are you not getting the pipe standard in Stainless Steel? We prepare a standard in each size and schedule, with the specified notches on the OD as well as ID. May be you are using a different set of specifications?

Best wishes.

Swamy

----------- Start Original Message -----------
: Thanks for your encouragement guys. I know a lot of people get their tickets and don't respect them and are just happy to rush through their work and not care about it. I'm a bit different in that respect, I've always believed the old "if a jobs worth doing, it's worth doing right."
: Anyway, what the plan is so far, and please, please, stop me if i'm wrong, we're going to purchase an A5, V1 and DAC blocks in both Carbon Steel and Stainless Steel. That way, I will be able to calibrate my probes. Draw up their beam spreads. And adjust them for DAC. I believe we will be using a sensitivity of DAC+14db.
: I will only be testing Carbon and Stainless Steel pipe up to 12".
: What is the acoustic velocity of 316SS? Shear and Compression?
: : Dear Nathan,
: : Congratulations for your success in exams and it is good that you are continuing the learning. While it would certainly be beneficial to check out the various published papers, it would also be practical to prepare specific standards for the material that you are trying to test. One of the most basic requirement of NDT is that as far as possible, the test standard (calibration block) should represent the material being tested. And if UT of plates, tubes/pipes is involved, I will be happy to help you since I worked in an organisation where tonnage quantities of austenitic stainless steel is routinely tested to various international standards.
: : With best wishes,
: : Swamy
: : Retired from Nuclear Fuel Complex


 
01:13 Nov-20-2008
Nathan
Re: Calibration for stainless steel. I am a bit confused now. I didn't realise stainless steel piping was so rare. It's nearly all they're putting in nowadays on our rigs.

The standard we use is a British Standard BS EN 1714 1998.

What i wanted the ss blocks for was to ascertain, Probe Refracted Angle, Probe Index Point Etc, using the V1 block.

The A5 block to create a beam spread/path overlay.

and the DAC block to create a Distance Amplitute Correction curve on the meter.

I would then be scanning stainless steel pipe as per my training.

I understand, and have read it is a good idea to have replicas of each item to be tested, infused with artificial defects. However, the amount of testing I will be doing is only really ad-hoc, field welds etc and varys wildly from item to item. It wouldn't be practical to say, find out I'm scanning a sch80 8" piping, then go away have a replica made, then go inspect the real thing. I don't believe that's the way it should be done.

If I was testing the above, day in, day out, then I understand it's a good idea.

I have tested welds under supervison for the last year, on/off, have just passed my level 2 PCN.

I have no problems testing carbon steel piping this way and have found two defects quite recently, on some 8" pipe. which I was pleased about.
----------- Start Original Message -----------
: : Here is a link to velocity tables.
: http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Reference%20Information/UT/ut_matlprop_metals.htm
------------ End Original Message ------------




 
01:16 Nov-20-2008
Nathan
Re: Calibration for stainless steel. No, unfortunately, we do not have a Level 3 employed. I haven't heard of this in the UK at all.

----------- Start Original Message -----------
: Nathan
: Doesnt your organisation employ an UT level 3 or retain outside level 3 services? For apparently non-routine tasks such as austenitic weld inspection, s/he should have compiled an appropriate procedure and devised a detailed instruction sheet. As Swamy indicated a welded sample containing artfully-positioned defects, preferably natural but artificial would do, should be available for operator familiarisation with the inspection characteristics..
: Newly-qualified people should be mentored through their initial experiences, not slung in at the deep end and left to sink or swim. Now for your sake I hope thats not the case Nathan, but you havent made any mention of guidance from within your company so far.
: And I am a little worried that you are skating over the surface by acquiring stainless blocks and then thinking thats OK now. Mark Davis showed you need to clarify if you have the right equipment for the job amongst other things.
: Good luck
------------ End Original Message ------------




 
06:24 Nov-20-2008

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Re: Calibration for stainless steel. Hi Nathan

I understand both your frustration and your willingness Nathan and it seems likely that you will go ahead and test the welds. Is a copy of the Weld Procedure Specification available as this will give you the pipe material specification and filler metal. If austenitic (non-magnetic) such as 316 with matching weld metal then refer to that as a restriction on your report, and also if you do not have the suitable probes which Mark Davis mentioned (twin crystal, high angle, low frequency longitudinal wave probes.) then that should be classified as another restriction - lack of suitable tools for the job.

If its not austenitic, but some other type of stainless steel (ferritic, martensitic, duplex) then do a Google search on the weld properties of that material to try to find out if the parent material/ filler material combination produces columnar grain growth

As you have referred twice to EN 1714 and in your last post, field welds I am certain its welds you have been assigned to inspect. Its notstainless welded pipework that is rare, as its especially used in corrosive environments, but its the ultrasonic testing which is if not rare then unusual as generally unless the weld thickness or configuration dictates otherwise, such welds are radiographed.

Good luck

Nigel


----------- Start Original Message -----------
: I am a bit confused now. I didn't realise stainless steel piping was so rare. It's nearly all they're putting in nowadays on our rigs.
: The standard we use is a British Standard BS EN 1714 1998.
: What i wanted the ss blocks for was to ascertain, Probe Refracted Angle, Probe Index Point Etc, using the V1 block.
: The A5 block to create a beam spread/path overlay.
: and the DAC block to create a Distance Amplitute Correction curve on the meter.
: I would then be scanning stainless steel pipe as per my training.
: I understand, and have read it is a good idea to have replicas of each item to be tested, infused with artificial defects. However, the amount of testing I will be doing is only really ad-hoc, field welds etc and varys wildly from item to item. It wouldn't be practical to say, find out I'm scanning a sch80 8" piping, then go away have a replica made, then go inspect the real thing. I don't believe that's the way it should be done.
: If I was testing the above, day in, day out, then I understand it's a good idea.
: I have tested welds under supervison for the last year, on/off, have just passed my level 2 PCN.
: I have no problems testing carbon steel piping this way and have found two defects quite recently, on some 8" pipe. which I was pleased about.
: : : Here is a link to velocity tables.
: : http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Reference%20Information/UT/ut_matlprop_metals.htm
------------ End Original Message ------------




 
02:11 Nov-20-2008

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Re: Calibration for stainless steel. I agree with you Nathan, but I would have other words for it than "unfortunate" which implies bad luck or accident. In fact its verging on irresponsiblity from the industry to allow this and its very worrying that you are working on presumably critical items without knowledgable supervision. This is NOT a denigration of you at all Nathan, i applaud your attempt to determine what constitutes sound inspection principles.

The NDT Level 3 should be available to support, instruct and mentor less experienced techs when and where neecessary.

Nigel


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: No, unfortunately, we do not have a Level 3 employed. I haven't heard of this in the UK at all.
: : Nathan
: : Doesnt your organisation employ an UT level 3 or retain outside level 3 services? For apparently non-routine tasks such as austenitic weld inspection, s/he should have compiled an appropriate procedure and devised a detailed instruction sheet. As Swamy indicated a welded sample containing artfully-positioned defects, preferably natural but artificial would do, should be available for operator familiarisation with the inspection characteristics..
: : Newly-qualified people should be mentored through their initial experiences, not slung in at the deep end and left to sink or swim. Now for your sake I hope thats not the case Nathan, but you havent made any mention of guidance from within your company so far.
: : And I am a little worried that you are skating over the surface by acquiring stainless blocks and then thinking thats OK now. Mark Davis showed you need to clarify if you have the right equipment for the job amongst other things.
: : Good luck
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