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Prisma is single group only – For multigroup you need the veo or veo+, I’d recommend the veo+ a significant performance improvement over the older version.
Also with Prisma make sure it has the options you need installed – It may not be cost effective to upgrade a second-hand set – Fully loaded the options are as much as the base price (or used to be).
The Prisma is a very good unit for the right applications, I still do a lot of training with it and recommend it highly, but it can ‘run out of steam’ if you need high speed or complex inspections performed.
Do you mean what code applies? What kind of work ae you doing?
As an alternative to purchasing second hand equipment would the availability to rent meet your requirements. If this would be of interest please contact Neil Christie at our Singapore office who will be able to assist, e-mail neil.Christie@ashtead.com.sg. Unfortunately we would not have any second hand equipment for sale at this time.
I do not know if there is an absolute method for this. In the book by Charlesworth and Temple there is an image (Figure 5-8) that shows all the arcs for the Compression, Shear and Rayleigh modes and indicates the top and bottom signals for a single planar flaw. This image is a VERY confusing “mess” to look at.
The authors state that “…it may be necessary to make a judgement as to which are the unconverted compression wave signals from the top and bottom of the defect and then calculate the positions and curve-shapes of all possible mode converted signals.”There are many multiplexers on the market. We can offer you also our multiplexer, but you must describe your needs with more details, since the construction of each multiplexer can be different.
It was explained a situation where TOFD is not ideal:
“In a situation where a high-low (poor fitup or mismatch) exists between two welded pieces, the transmitted pulse forms two signals off the opposite wall, one from the
higher side arriving prior to the one from the lower. The amount of high-low can be accurately assessed but if a defect occurred in the lower of the two sides the backwall
signal from the higher side could obscure the defect.
In both cases a pulse-echo technique can be adapted to
inspect these areas to provide improved coverage where TOFD is not ideal”.
