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Technical Discussions
Jeong
Jeong
09:56 Mar-25-2016
LED-UV Intensity

Hi~
I have LED-UV of intensity 70mm 3200uW/Cm^2.

(ASME UV Intensity 38Cm 1000uW/Cm^2)

It is LED -UV use for any problems from ASME Code.?


If no problems call for explanation.

1
 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
11:39 Mar-25-2016
Re: LED-UV Intensity
In Reply to Jeong at 09:56 Mar-25-2016 (Opening).




Hi, Jeong!
I had a look to ASME and article 6 hadn't limit for size
What is number of article which refes "38Cm"
Then I can explain OK?
(but i think, that 70mm is size of lamp and 38 look like a wawelength of UF ligth in some units; then we can't compare these values)
Regards, Volodymyr
 
 Reply 
 
Theo Micottis
Italy, Joined May 2013, 81

Theo Micottis

Italy,
Joined May 2013
81
12:20 Mar-25-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 11:39 Mar-25-2016 .

Hi Jeong, my interpretetion is the following:
70mm is the distance between the black light source and the surface.
38cm is the distance between your eyes and the surface, usually the maximun distance allowed is 60cm.
ASME V Art.9: Direct visual examination may usually be made when access is sufficient to place the eye within 24 in.(600 mm) of the surface to be examined and at an angle not less than 30 deg to the surface to be examined.
Put the black light lamp at your test distance and verify with a certified radiometer if you reach the minimum intensity of 1000 μW/cm2 on the surface. Regards Theo

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
12:57 Mar-25-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 11:39 Mar-25-2016 .

If these 70mm and 38Cm are distances of controlled lamp radiation
(70 mm- 3200uW/Cm^2 and
380mm - 1000uW/Cm^2)
we can use proportion
Light propagates and uW/Cm^2 depend on distance.
But inversely proportional to the square of the distance.
So, if You use lamp
70 mm- 3200uW/Cm^2 its radiation will be on distance 380mm less
see, plz
3200*(70^2)/(380^2) = 108uW/Cm^2
Yu can't place this lamp on such distance. Too far!
What is exit?
put closer - it is good idea 125 mm
3200*(70^2)/(125^2) = 1003uW/Cm^2
More then you wrote (ASME UV Intensity 38Cm 1000uW/Cm^2)
ONLY one question!
Where you found 38Cm
Regard's, Volodymyr

 
 Reply 
 
N B Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
13:22 Mar-25-2016
Re: LED-UV Intensity
In Reply to Jeong at 09:56 Mar-25-2016 (Opening).

Dear Jeong,

If the intensity at 70mm is as what told by you, then the intensity at 380mm from inspection surface to bulb shall be very less as compared to 1000uW/cm2 which is a standard requirement as per T-674.4
So, you cannot use this LED-UV light.

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
14:32 Mar-25-2016
Re: LED-UV Intensity
In Reply to Jeong at 09:56 Mar-25-2016 (Opening).




Why I supposed about 38Cm
 
 Reply 
 
Andreas
NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh, Germany, Joined Oct 1999, 131

Andreas

NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh,
Germany,
Joined Oct 1999
131
09:01 Mar-26-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 14:32 Mar-25-2016 .

Gents ,
you Need to have a certain distance to verify the intensity. Normally you should reach at least the 1000µW/sqcm at inspection distance.
Some customer specs and specification tell you in which distance you should measure.

70mm in nonsence , you will blind yourelf.
38 cm app 15" , this will agree with the DS-1 Standard.
SOP of my Company required that the intensty is measared at 35 & 55 cm.

Regards

Andreas

1
 
 Reply 
 
Oliviero
NDT Inspector,
Quality Control srl, Italy, Joined Oct 2008, 414

Oliviero

NDT Inspector,
Quality Control srl,
Italy,
Joined Oct 2008
414
10:58 Mar-28-2016
Re: LED-UV Intensity
In Reply to Jeong at 09:56 Mar-25-2016 (Opening).

What is important is the light intensity on the surface when the evaluation of indication is performed.
How to obtain the required light intensity? With a light source which has the adequate lighting at the distance needed.
It is necessary to measure the light intensity on the surface and determining the lamp distance to be maintained for evaluation.
Any lamp could reach the minimum required intensity, but each lamp will be at a different distance from the surface and it will lighting a different surface siza area.
The proper lighting condition shall be determined for interpretation. Starting from the minimum lighting intensity, choose the lamp determine the minimum distance from the surface and the size area illuminated for interpretation.

 
 Reply 
 
Ashfaq
United Arab Emirates (UAE), Joined May 2015, 8

Ashfaq

United Arab Emirates (UAE),
Joined May 2015
8
11:41 Mar-28-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 12:57 Mar-25-2016 .

Dear Volodymyr,

38cm is the distance between the UV Light and and the test piece surface or UV Meter on which intensity is checked.

I totally agreed with Andreas and i would say the best answer as he posted.

Regards

 
 Reply 
 
Ashfaq
United Arab Emirates (UAE), Joined May 2015, 8

Ashfaq

United Arab Emirates (UAE),
Joined May 2015
8
11:56 Mar-28-2016
Re: LED-UV Intensity
In Reply to Ashfaq at 11:41 Mar-28-2016 .

Dear Oliviero,

As per DS-1 standard the minimum illumination level (white light) at the inspection surface shall be 50 foot-candles. We can measure this with light meter. The requirements do not apply to direct sunlight conditions. If adjustments are required to the light intensity level at the inspection surface then we need to measure.

When we do black light inspection the light intensity at least 1000µW/sqcm is required.

Regards

Ashfaq

 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 526

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
526
12:16 Mar-28-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 12:57 Mar-25-2016 .

"But inversely proportional to the square of the distance."

This is for a point source. Typical uv lamp at 70mm is far too large for this to apply.

From 400 to 600 MM. would probably be approximately valid.

1
 
 Reply 
 
riccardo corioni
Consultant, - NDT inspector
ing. corioni, Italy, Joined Jul 2009, 4

riccardo corioni

Consultant, - NDT inspector
ing. corioni,
Italy,
Joined Jul 2009
4
15:35 Mar-28-2016
Re: LED-UV Intensity
In Reply to Joe Buckley at 12:16 Mar-28-2016 .

38 nm=39 exp (-9) m or 38 nanometer
38 nm are different from 38 cm=380 mm..............
my god!!!

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
17:59 Mar-28-2016
Re: LED-UV Intensity
In Reply to riccardo corioni at 15:35 Mar-28-2016 .

:))))
undoubtedly "38 nm" is different from 38 cm=380 mm
We just try to know: from where "38" digital taken?
Proportion get us all ansvers. (see up)
Projected light falls on spherical surface and is weaken with distance.
Because square of spherical surface is 4*pi*r^2.
So we have got inversely proportional dependency of r^2, r- radius, in our case distance.
So we can count any illumination.
Regards, Volodymyr.

 
 Reply 
 
Frank Lund
R & D,
United Kingdom, Joined Apr 2005, 222

Frank Lund

R & D,
United Kingdom,
Joined Apr 2005
222
20:08 Mar-28-2016
Re: LED-UV Intensity
In Reply to Volodymyr at 17:59 Mar-28-2016 .

It is a matter of scale. At 93 million miles away, we can consider the Sun to be a point source for most purposes.

For sources having a radiating element with a size that is significant in relation to the distance of measurement of the luminous flux, the Inverse Square Law is too simplistic.

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
22:13 Mar-28-2016
Re: LED-UV Intensity
In Reply to Frank Lund at 20:08 Mar-28-2016 .

If You please, have a look UP (12:57 Mar-25-2016), there is radiation and distance.
If we need higher precision
1. Take the integral, dividing the surface of the lamp at the elementary sources.
Each of them emits a single source for the above (12:57 Mar-25-2016) mentioned law. Illumination at the nearest point of surface is amount from each of sources. And we need this way???
2. Experimental way.
It seems that the discussion goes into the theoretical domain. And we're just going to do at work.

 
 Reply 
 
Andreas
NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh, Germany, Joined Oct 1999, 131

Andreas

NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh,
Germany,
Joined Oct 1999
131
08:07 Mar-29-2016
Re: LED-UV Intensity
In Reply to Jeong at 09:56 Mar-25-2016 (Opening).

Please read article from the "Material Evalution " Magazin from June 2013.
A Problem with UV-Lead is that they produce also White light and not only UV- light .


Regards

Andreas

 
 Reply 
 

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