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- since 1996 -

Phoenix Inspection Systems Limited
Design and manufacture ultrasonic Transducers, Scanners and Custom Solutions for NDT inspections. Innovators in NDT technology
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Technical Discussions
Ken
Senior Level III
USA, Joined Jan 2000, 14

Ken

Senior Level III
USA,
Joined Jan 2000
14
22:54 Jul-20-2010
Stadium Light Poles

Does anyone have experience with NDT of stadium light poles. It seems asome are having cracking issues at the base where flange is fillet welded onto the pole. I can find no guidence on inspection methods and my current recomendation is a magparticle exam. I am thinking that the galvinzed coating should be removed at the weld area as it is not bonded very well. I was thinking AC using dry powder. Any other suggestions or concerns I should have?

 
 Reply 
 
Ken
Senior Level III
USA, Joined Jan 2000, 14

Ken

Senior Level III
USA,
Joined Jan 2000
14
22:58 Jul-20-2010
Re: Stadium Light Poles
In Reply to Ken at 22:54 Jul-20-2010 (Opening).

http://www.cpsc.gov/cpscpub/prerel/prhtml09/09321.html

An example of the issues can be found at the above link

 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 528

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
528
23:33 Jul-20-2010
Re: Stadium Light Poles
In Reply to Ken at 22:58 Jul-20-2010 .

Did some work on this issue nearly 20 years ago following a traffic light collapse.

Would recommend either Eddy current with Orthogonal wound "weldscan" probes per EN1711. Or ACFM.

Joe

 
 Reply 
 
Jon Wallis
NDT Inspector, -
Netherlands, Joined Feb 2010, 626

Jon Wallis

NDT Inspector, -
Netherlands,
Joined Feb 2010
626
09:21 Jul-21-2010
Re: Stadium Light Poles
In Reply to Joe Buckley at 23:33 Jul-20-2010 .

...and don't forget to do a thorough visual examination of the welds. I did some work on these types of construction at an airport and on wind turbine towers. Those welds were fully penetrated so we did UT on them as well as MT. You are looking for fatigue cracking so I suggest you MT them with the black / white method. Ok, they are galvanised but fatigue cracking should show up (don't forget to mention this limitation in your report). Removing a galvanised coating from a weld surface would be quite difficult in the field. Can you look inside the towers, cracking may be initiating from the inside weld? Are they back-welded? If, as you say, some are cracking there is a design issue and maybe some sort of reinforcement will be necessary - thats not an ndt problem but should be considered.

 
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Rolf
Director,
NDT.net, Germany, Joined Nov 1998, 616

Rolf

Director,
NDT.net,
Germany,
Joined Nov 1998
616
10:27 Jul-21-2010
Re: Stadium Light Poles
In Reply to Ken at 22:58 Jul-20-2010 .


Close-up - crack near weld that joins the pole to its base plate

Find the recent release from U.S. Consumer Product Safety Commission (CPSC) dated July 6, 2010 here:
http://www.cpsc.gov/CPSCPUB/PREREL/prhtml10/10295.html
 
 Reply 
 
ken
Senior Level III
USA, Joined Jan 2000, 14

ken

Senior Level III
USA,
Joined Jan 2000
14
15:32 Jul-21-2010
Re: Stadium Light Poles
In Reply to Rolf at 10:27 Jul-21-2010 .

Thanks so much for all you guys help. One more question. I was thinking that the area of intrest should be sandblasted as the galvanized coating is poorly bonded and cracking off in a lot of the areas around the weld. Would you guys suggest this or just a good wire brushing. Also, would you do a DC as well as AC inspection?

 
 Reply 
 
ken
Senior Level III
USA, Joined Jan 2000, 14

ken

Senior Level III
USA,
Joined Jan 2000
14
15:40 Jul-21-2010
Re: Stadium Light Poles
In Reply to Jon Wallis at 09:21 Jul-21-2010 .

Jon, it is possible to look inside thru the wiring port. Would involve using a boroscope but is possible. Im just not sure what we could tell. As far as I can tell, the design is using a slip on flange fillet welded to the pole run pipe which seems to be flared for the fit. We have been able to get no design info on this just observation as the manufacture is out of business. Also, it seems some of the welds are sub-arc completly and some have a first pass of either FCAW or GMAW. The long seams in the pole pipe are not good but so far these are not issues of concern though they may need to be

 
 Reply 
 
Jon Wallis
NDT Inspector, -
Netherlands, Joined Feb 2010, 626

Jon Wallis

NDT Inspector, -
Netherlands,
Joined Feb 2010
626
20:18 Jul-21-2010
Re: Stadium Light Poles
In Reply to ken at 15:40 Jul-21-2010 .

With this design you are right, it probably wouldn't be of much use to look inside the tower. The constructions that I looked at were simply welded with a halve vee between the tower pipe and the base flange which was then bolted to a concrete base.
If you look at the photo that Rolf posted you can see the type of fatigue crack that would appear in these towers. This is not a 5mm long indication as may be found in new -build welds! A wire brush and an ac yoke with black / white method should do fine. fatigue cracks aren't sub-surface.

 
 Reply 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 889

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
889
20:38 Jul-21-2010
Re: Stadium Light Poles
In Reply to ken at 15:32 Jul-21-2010 .

Ken,

Since you will be looking for fatigue crack, I would use a yoke in AC mode. Dry particles would work fine, but if you want to take pictures I think a white contrast with black ink would work better.

 
 Reply 
 
ken
Senior Level III
USA, Joined Jan 2000, 14

ken

Senior Level III
USA,
Joined Jan 2000
14
21:17 Jul-22-2010
Re: Stadium Light Poles
In Reply to Michel Couture at 20:38 Jul-21-2010 .

Thanks for all of your help, I love this fourm

 
 Reply 
 
Roger Duwe
NDT Inspector, API-510, 570, 653
MISTRAS, USA, Joined Jan 2009, 148

Roger Duwe

NDT Inspector, API-510, 570, 653
MISTRAS,
USA,
Joined Jan 2009
148
03:48 Jul-23-2010
Re: Stadium Light Poles
In Reply to ken at 21:17 Jul-22-2010 .

Fairly common problem, but not well documented. These are 'Toe Cracks' caused by the hot-dip galvanizing. In my expereience in two 'pole shops', about 1 in 5 poles exhibits this problem. Immediatly after galv, they are only 1-2 mm in depth, easy to excavate & weld repair. Initially, they tend to be 50-250 mm long, one location on the pole only.

Accurate results can be easily obtained with a 6-12mm round 2.25 MHz shearwave transducer at a 45-deg angle. Verify complete excavation with Magnetic Particle prior to rewelding. You'll be able to find these toe-cracks faster than 2 welders can correct them.

 
 Reply 
 
Rolf
Director,
NDT.net, Germany, Joined Nov 1998, 616

Rolf

Director,
NDT.net,
Germany,
Joined Nov 1998
616
22:09 Jan-02-2011
Re: Stadium Light Poles
In Reply to Ken at 22:54 Jul-20-2010 (Opening).

If one is still interested in this topic:
Northwest stadium pole problems found, fixed
http://www.star-telegram.com/2010/12/14/2703951/northwest-stadium-pole-problems.html

 
 Reply 
 

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