where expertise comes together - since 1996 -

# The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

 Zawada NDTSuppliers of instruments to test steel wire ropes in-situ, using magnetic, non-destructive method.
 1652 views
Technical Discussions
John Wiliams
John Wiliams
07:22 May-09-2000
Double wall double image

What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120

Uli Mletzko
R & D, Retired
Germany, Joined Nov 1998, 89

Uli Mletzko

R & D, Retired
Germany,
Joined Nov 1998
89
08:18 May-09-2000
Re: Double wall double image
: What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120

If your term 'double image' is referring to the situation, where you have a 'small' diameter of the tube (> 100 mm) and a 'large' source distance (some 100 mm away from the tube), there is no difference. Either 0/60/120 or 0/120/240 deg. interleave are possible (and allowed due to the European or former German standards).

Only in the situation of 'Double wall single image' (large tube diameter, source near the outer surface of the tube), only 0/120/240 deg are possible, of course.

OK ?

Best regards
Uli Mletzko, NDT Group,
State Materials Testing Institute (MPA),
University of Stuttgart, Germany

Uli Mletzko
R & D, Retired
Germany, Joined Nov 1998, 89

Uli Mletzko

R & D, Retired
Germany,
Joined Nov 1998
89
08:24 May-09-2000
Re: Double wall double image

: diameter of the tube (> 100 mm)

Sorry for my mistyping. Of course it should be

diameter of the tube (< 100 mm) (less than 100 mm)

Best regards
Uli Mletzko, NDT Group,
State Materials Testing Institute (MPA),
University of Stuttgart, Germany

Jacques Parent
Jacques Parent
08:49 May-09-2000
Re: Double wall double image
: What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120

Double wall exposure and superimposed double wall viewing only
0-120-240
or
0-60-120

The 240 and 60 shots provide the same coverage with opposite top and bottom walls.

I believe the 60 shot is prefered because it is easier to set up from a shooting point of view. All three shots are taken from the same quadrant.

Regards
jp

Nick Welland
Nick Welland
01:12 May-11-2000
Re: Double wall double image
: : What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120

: Double wall exposure and superimposed double wall viewing only
: 0-120-240
: or
: 0-60-120

: The 240 and 60 shots provide the same coverage with opposite top and bottom walls.

: I believe the 60 shot is prefered because it is easier to set up from a shooting point of view. All three shots are taken from the same quadrant.

: Regards
: jp

I agree that on site the 0, 60, 120 is usually easier to set up and provides the same coverage. But when considering the loss of sensitivity with double-wall viewing, especially superimposed, the 0-120-240 scheme would seem to ensure the favourable near-film location is available in all quadrants.
Nick

Jacques Parent
Jacques Parent
04:51 May-11-2000
Re: Double wall double image
M. Welland;

I know what you are saying and I do not disagree.
But:
1) 0, 120, 240 shooting on small diameter (<100mm) does not ensure complete coverage on the film side. One still need to evaluate the source side image.

2) Source side IQI's (as required by Code) ensure equivalent and acceptable sensitivity.

In my opinion both techniques are acceptable and the choice should be left to the "shooter"

Regards
jp

Nick Welland
Nick Welland
02:11 May-12-2000
Re: Double wall double image
: M. Welland;

: I know what you are saying and I do not disagree.
: But:
: 1) 0, 120, 240 shooting on small diameter (<100mm) does not ensure complete coverage on the film side. One still need to evaluate the source side image.

: 2) Source side IQI's (as required by Code) ensure equivalent and acceptable sensitivity.

: In my opinion both techniques are acceptable and the choice should be left to the "shooter"

: Regards
: jp

OK Jacques, c'est entendu, either technique is acceptable. I was trying to see whether there would in fact be any justification for preferring 0-120-240.

Regards
Nick Welland

john williams
john williams
04:17 May-18-2000
Re: Double wall double image
: What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120
What is the best method to x-ray two plates of different thicknesses (12mm to 40mm). Also is it true that if you increase the kv by 20 your exposure time is reduced by 50%.

Uli Mletzko
R & D, Retired
Germany, Joined Nov 1998, 89

Uli Mletzko

R & D, Retired
Germany,
Joined Nov 1998
89
07:07 May-19-2000
Re: Double wall double image
: : What is the reasoning behind when taking 3 shots at 120 degrees to each other rather than 0deg,60 & 120

Unfortunately you have posted your question as follow-up to a wrong subject. Posting of answers therefore may be difficult.

: What is the best method to x-ray two plates of different thicknesses (12mm to 40mm).

You have to know the exposure chart of the x-ray tube (milliamps depending on wall thickness, with voltage as parameter, for a certain film) and the exposure chart (with gamma information) of that film. Then you have the choice for the maximum density (thin wall) and the minimum density (thick wall). The output should be one single voltage, where the task could be solved.
To have a wallthickness difference of 22 mm within a density range of 2 (2.0 to 4.0), you will need high energy like Cobalt 60 or a linear accelerator. The task can't be solved with standard x-ray tubes (you need a flat inclination of exposure chart line).

: Also is it true that if you increase the kv by 20 your exposure time is reduced by 50%.

This is depending not only from the increase, but also from the voltage itself. The output (intensity) of a x-ray tube is depending roughly from the square of the actual peak voltage (integral of or area below the spectral intensity curve). The exposure is depending roughly on the inverse of the intensity.

Regards
Uli Mletzko
MPA, University of Stuttgart, Germany

saeed payam
NDT Inspector
Iran, Joined May 2002, 1

saeed payam

NDT Inspector
Iran,
Joined May 2002
1
04:39 May-22-2002
Re:film
can you lead me to a site wich it able to show by,online,any welds defect on radiographic film or send it by e-mail to me please.

Product Spotlight

#### FMC/TFM

Next generation for Phased Array UT is here now with FMC/TFM! Have higher resolution imaging, impr
...
oved signal to noise ratio, characterize, size and analyze defects better with access to several wave mode views and save raw FMC data for higher quality analysis.  Some of the benefits are:
• Beautiful Image! Easier to understand what you're looking at
• Completely focused in entire image or volume
• Much easier to define setups before inspection
• Easier to decipher geometry echoes from real defects
• Oriented defects (e.g. cracks) are imaged better
• See image from different wave modes from one FMC inspection
• FMC data can be reprocessed/analyzed without going back to the field
>

#### OmniScan™ X3 flaw detector

The OmniScan X3 flaw detector is a complete phased array toolbox. Powerful tools, like total focus
...
ing method (TFM) images and advanced visualization capabilities, enable you to complete your inspection with greater confidence.
>

#### ISAFE3 Intrinsically Safe Sensor System

ISAFE3 intrinsically safe sensor system of Vallen Systeme is especially targeted at the petrochemica
...
l - as well as oil and gas transportation industry. The sensor system is designed for permanent monitoring or periodic inspection tasks. Sensors are available for different AE-frequency ranges optimized for corrosion and fatigue crack detection and other applications. The ISAFE 3 sensor system consists of an AE-sensor (model ISAS3) certified according to ATEX/IEC for installation in zone 0, gas group IIC, IP68, 20 to +60 °C, and a signal isolator (model SISO3) certified for installation in zone 2. An ISAS3 sensor can be mounted in atmosphere or submerged, e.g. in water or crude oil. It is supported by mounting tools for temporary (magnets) or permanent (welded) installation. ISAFE3 supports automatic sensor coupling test and can be used with any AE signal processor supporting 28V supply at 90 mA peak, e.g. Vallen Systeme ASIP-2/A.
>

#### Customized Probes and Transducers

With a strong development department and our own piezocomposite production, we accompany you from th
...
e first product idea to serial production. Our scientists are continuously researching new methods in the field of ultrasonic measurement technology. The progress achieved enables us to offer you optimal solutions.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window