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- since 1996 -
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Technical Discussions
Derrick Parker
Derrick Parker
01:53 Jun-19-2010
The "Cadillac" of ToFD Systems?

If cost were not the primary consideration, and portability was not an issue, what would be the best ToFD set-up available on the market? Pulser/receiver and transducers. Not really looking at a wide range of exotic materials. For the query's sake, consider carbon steel, WT 30mm.

 
 Reply 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 868

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
868
04:22 Jun-19-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Derrick Parker at 01:53 Jun-19-2010 (Opening).

Derrick,

I think you need to provide a little more info. With TOFD like anything else in NDT, we try to keep thingssimple, yet the key here is repeatability. Having said that With the knwoleadge that we acquire through experience and experimentation, we are starting to realise that the idea of one probe or set of probes and equipment can and will do everything is becoming more far fetched.

I suspect that you want to inspect welds in Carbon Steel with a 30 mm WT? As far as TOFD is concerned, you could do it with a pair of 5 MHz 6 mm transducers and 60 degree wedge. I haven't dopne the proper calulation so I don't know if one pair of TOFD transducers will cover the area of interest; you may need another pair to cover the bottom half. Now, if you are doing some weld inspection, TOFD can't do it alone. ASME for example require another UT method such as PAUT to cover the Weld Cap and the Toe.

In the end, everything is dependent on the code that you are working to.

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
06:21 Jun-19-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Michel Couture at 04:22 Jun-19-2010 .

Any of the nuclear nozzle weld inspection rigs might break your back as well as your bank! Research them and decide which you want to go for.

 
 Reply 
 
Derrick Parker
Derrick Parker
15:12 Jun-19-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Derrick Parker at 01:53 Jun-19-2010 (Opening).

I'm not concerned about codes or keeping it simple at this stage, just the best resolution possible. As Michael notes, experience and experimentation are key to developing techniques. But a good starting point would be the best available equipment.

Any brand names or models which stand out above the rest?

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1286

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1286
15:12 Jun-19-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Derrick Parker at 01:53 Jun-19-2010 (Opening).

Derrick, I have had the opportunity to work with 6 or 7 different TOFD systems. There several aspects to consider in your question. A TOFD system is, at its fundamental basis, a mix of hardware and software (like any other AUT system). If we now take out the mechanical aspects for moving probes around the component (since this could equal or exceed some of the costs of the basic TOFD systems), we are left with software and the pulser-receiver hardware. The nicest hardware (pulser-receiver components) I have seen provide a 10 or 12bit digitisation with log amplifiers. In addition to a high voltage tunable pulser this unit's receiver gives the ability to add or subtract softwared gain without any electronic saturation or amplifier noise! The associated user interface and post-processing options I saw were limited.
Other units do not have such a clean signal from the hardware but have great post-processing features like lateral wave equalisation, lateral wave straightening and subtraction, and SAFT image corrections. Many systems have these post-processing features but some are more user-friendly than others. Another software feature is the special computations that are requried for special applications (like T-joints). No one system seems to have it all; but if you eventually want your system to have many of the features, it would be best to have a good "shopping list" and get assurances from any supplier that they will be able to modify/add to their software the special aspects you are looking for.

 
 Reply 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 280

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
280
15:10 Jun-20-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Ed Ginzel at 15:12 Jun-19-2010 .

Ed sums up a lot of the really good points - one observation is do not go for a cheap and flimsy scanner. recently I have audited numerous systems where a lot of money is spent on the UT side frorit all to fall apart with a cheap and non robust mechanical device.

 
 Reply 
 
Derrick Parker
Derrick Parker
20:22 Jun-20-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to John O'Brien at 15:10 Jun-20-2010 .

Thanks for taking the time to answer. This inspired some new direction in my Googling. I'm going to consider getting something built and incorporating it into an existing software platform. We've been watching welds get rejected due to the limitations of an aging ToFD set-up. Time to sort this out.

I'm open to any further suggestons. Thanks again.

 
 Reply 
 
massimo carminati
massimo carminati
20:58 Jun-21-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Derrick Parker at 01:53 Jun-19-2010 (Opening).

I would completely quote Ed's comment. I've started performing Tofd inspection in the late nineties and, at that time, I was using the R/D Tech utomoscan. From the ultrasonic point of view and after more than ten years, I think that it was the best unit ever tried. Unfortunately I think R/D Tech, now, unfortunately, Olympus, has problems even with the spare parts so that this unit is out of service. Back to the features, we have to deal with low amplitude signals so:
First issue: Square wave pulser with pulse width fine tuning and relatively high voltage.
An excellent low noise receiver with a wide selection of frequency filters (HP and LP).
Signal averaging for noise suppression.
Good insulations between channels (some units have interference problems between different channels)
A field proof software, powerful and........like R/D Tech Tomoview, even with its bugs.
Piezocomposite probes with rexolite wedges is a must have.

With this thickness range, I would not consider a remote preamplifier, unless you can use relatively short cables (less than 15 meters).

Last but not least a good scanner; pay attention to the probeholder "wrist" which should guarantee the fastest reaction to surface inequalities.

The very last comment: after sales service and knowledge of the people you are dealing with; the value added can really make the difference.

 
 Reply 
 
LUIS GANHAO
Engineering,
USA, Joined Sep 2008, 25

LUIS GANHAO

Engineering,
USA,
Joined Sep 2008
25
22:23 Jun-21-2010
Re: The "Cadillac" of ToFD Systems?
In Reply to Derrick Parker at 01:53 Jun-19-2010 (Opening).

Dear Derrick,

I start with TOFD in 1991 and by the time the equipment that we had was the Zipscan 3 from Sonomatic, and this was a huge equipment but was the first TOFD equipment from England, after that we bought the Microplus from AEA Technology and was a very good equipment (software, probes , etc...). Today the company in England that still fabicating the Microplus is Veritec Sonomatic, they have improved a lot these equipments as well as the softwares.

 
 Reply 
 

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