Corrosion dye test - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 09-21-2011
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,382
Thanks: 47
Thanked 3 Times in 3 Posts
Rep Power: 7
L124C is on a distinguished road
Corrosion dye test

I did a corrosion dye test on some backstay hardware. First, you clean the hardware with "cleaner/remover" (seems like acetone). Second, you spray the dye on (see picture), and leave it on for "one to thirty minutes" (what happens if I leave it on for 31 minutes?). Third, you clean off the dye with the cleaner/remover, then apply "developer" which brings back the dye in any corroded areas. The test indicated corrosion in two places where it was apparent without the test. However, it also illuminated about an eighth of the surface of the the hardware in the picture. This was not a crack or line, but an entire section which appeared as perfectly sound stainless without the test. I wish I took a picture, but I didn't. Picture the top left section of the hardware (next to the hole) red, and the rest of the piece, shiny stainless steel. Anyone have any idea what this might indicate?
Attached Thumbnails
Corrosion dye test-0920111434.jpg  

Last edited by L124C; 09-21-2011 at 04:07 PM.
Reply With Quote Share with Facebook
  #2  
Old 09-21-2011
Senior Member
 
Join Date: Apr 2003
Posts: 4,192
Thanks: 50
Thanked 37 Times in 36 Posts
Rep Power: 14
knothead has a spectacular aura about knothead has a spectacular aura about knothead has a spectacular aura about
I can only guess, but it's sort of an educated one. I think what you're seeing is metal fatigue. I have never used the dye. I just clean the metal with a scotch bright pad and use a magnifying glass to inspect things. But I have often seen toggles, tangs, chainplates and eyes of all sorts fatigued in the same area. Under a big enough load, holes will even get oblong. Add some corrosion and you have a crack.

Seriously, I urge you to just replace all those t-bolts. If your turnbuckle bodies are bronze and in good shape, you can just replace the t-bolts.
Reply With Quote Share with Facebook
  #3  
Old 09-21-2011
RichH's Avatar
Senior Member
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 2,694
Thanks: 9
Thanked 56 Times in 50 Posts
Rep Power: 15
RichH will become famous soon enough
Dye Penetrant inspections are *not* for corrosion. Such testing it to visualize micro-cracks as evidence of the beginnings of FATIGUE or 'brittle failure' of metals.
If stainless materials are 'fatigued' and with the accompanying micro-cracks, then for sure, crevice corrosion will simultaneously begin inside the micro-cracks if the cracks are subject to 'constant wetting'.

example: WeldingDepot -- Magnaflux® Spotcheck Dye Penetrant Inspection 16oz can

To perform the dye penetrant test correctly you have to thoroughly wipe the red dye from the surface of the part being examined, the dye that penetrates into cracks and pin holes and therefore is not 'wiped away' will later be a reservoir for the 'developer' and will show a 'red line' (crack) or 'spot' (pin hole) in the developer.

Here's an example of the procedure for using 'dye penetrant':
How to Use Magnaflux Dye Penetrant | eHow.com

Last edited by RichH; 09-21-2011 at 06:31 PM.
Reply With Quote Share with Facebook
  #4  
Old 09-21-2011
SloopJonB's Avatar
Senior Moment Member
 
Join Date: Jun 2011
Location: West Vancouver B.C.
Posts: 10,598
Thanks: 56
Thanked 48 Times in 45 Posts
Rep Power: 4
SloopJonB will become famous soon enough
Quote:
Originally Posted by L124C View Post
I did a corrosion dye test on some backstay hardware. First, you clean the hardware with "cleaner/remover" (seems like acetone). Second, you spray the dye on (see picture), and leave it on for "one to thirty minutes" (what happens if I leave it on for 31 minutes?). Third, you clean off the dye with the cleaner/remover, then apply "developer" which brings back the dye in any corroded areas. The test indicated corrosion in two places where it was apparent without the test. However, it also illuminated about an eighth of the surface of the the hardware in the picture. This was not a crack or line, but an entire section which appeared as perfectly sound stainless without the test. I wish I took a picture, but I didn't. Picture the top left section of the hardware (next to the hole) red, and the rest of the piece, shiny stainless steel. Anyone have any idea what this might indicate?
My guess is porosity, perhaps factory original. Those dyes are penetrants and to colour an area, rather than a line there would have to be some kind of porosity to the metal - this is not a form of cumulative failure mode AFAIK.

Those T-bolt turnbuckles are nasty things IMHO - replace them with proper jaw to eye ends.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.
Reply With Quote Share with Facebook
  #5  
Old 09-21-2011
pdqaltair's Avatar
Senior Member
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,082
Thanks: 1
Thanked 23 Times in 23 Posts
Rep Power: 6
pdqaltair is on a distinguished road
Quote:
Originally Posted by L124C View Post
Picture the top left section of the hardware (next to the hole) red, and the rest of the piece, shiny stainless steel. Anyone have any idea what this might indicate?
I find the description of the red portion a bit unclear, but if you mean the bend area of the toggle, next to the hole, it is almost certainly fatigue. My last boat would reliably fracture that piece every 5-8 years. it would start as a great number of micro-cracks, resembling surface roughness, and then it would start to open up.

Good that you caught it.

Yes, penatrant testing can show up porosity, but it is very rare. It is sometimes seen in carbon steel fuel tanks that have seen salt, sulfur, and bacteria. It is possible for a tank to ooze oil without any identifiable pinhole.
__________________
(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #6  
Old 09-22-2011
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,382
Thanks: 47
Thanked 3 Times in 3 Posts
Rep Power: 7
L124C is on a distinguished road
Quote:
Originally Posted by knothead View Post
Seriously, I urge you to just replace all those t-bolts. If your turnbuckle bodies are bronze and in good shape, you can just replace the t-bolts.
As I indicated in the other thread Backstay hardware, threaded or not? , I fully intend to replace the parts. This thread was posted strictly out of curiosity. Just trying to learn.
Reply With Quote Share with Facebook
  #7  
Old 09-22-2011
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,382
Thanks: 47
Thanked 3 Times in 3 Posts
Rep Power: 7
L124C is on a distinguished road
Quote:
Originally Posted by RichH View Post
To perform the dye penetrant test correctly you have to thoroughly wipe the red dye from the surface of the part being examined, the dye that penetrates into cracks and pin holes and therefore is not 'wiped away' will later be a reservoir for the 'developer' and will show a 'red line' (crack) or 'spot' (pin hole) in the developer.
I did clean off the dye using the cleaner/remover, before applying the developer. I left that out because I thought it was obvious. Guess I was wrong.
Reply With Quote Share with Facebook
  #8  
Old 09-22-2011
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,382
Thanks: 47
Thanked 3 Times in 3 Posts
Rep Power: 7
L124C is on a distinguished road
Quote:
Originally Posted by pdqaltair View Post
I find the description of the red portion a bit unclear, but if you mean the bend area of the toggle, next to the hole, it is almost certainly fatigue. My last boat would reliably fracture that piece every 5-8 years. it would start as a great number of micro-cracks, resembling surface roughness, and then it would start to open up.
Yes, penatrant testing can show up porosity, but it is very rare. It is sometimes seen in carbon steel fuel tanks that have seen salt, sulfur, and bacteria. It is possible for a tank to ooze oil without any identifiable pinhole.
I could kick my self for not taking a picture of the dye resurfacing! I used "paint" to mark the surface yellow where the dye resurfaced in this picture. There is no roughness to the surface, and it appears normal to my eye. Think I'll get a magnifying glass and have a look.
Attached Thumbnails
Corrosion dye test-0920111434.jpg  
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is this wire corrosion? L124C Electrical Systems 32 03-01-2011 01:59 AM
Serious corrosion mystery pwinkler Gear & Maintenance 8 09-10-2008 06:29 PM
Swage Corrosion tdw Gear & Maintenance 17 06-18-2007 12:47 PM
Rust and Corrosion. wind_magic Gear & Maintenance 4 06-17-2007 10:13 PM
Galvanic Corrosion Duke 7184 Gear & Maintenance 11 03-17-2007 09:09 AM


All times are GMT -4. The time now is 04:29 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012