Corrosion dye test - SailNet Community
 
LinkBack Thread Tools
post #1 of 8 Old 09-21-2011 Thread Starter
Senior Member
 
L124C's Avatar
 
Join Date: Oct 2007
Posts: 1,398
Thanks: 51
Thanked 3 Times in 3 Posts
Rep Power: 8
 
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
0920111434.jpg  

Last edited by L124C; 09-21-2011 at 04:07 PM.
L124C is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 8 Old 09-21-2011
Senior Member
 
Join Date: Apr 2003
Posts: 4,192
Thanks: 50
Thanked 38 Times in 37 Posts
Rep Power: 15
     
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.
knothead is offline  
Quote Quick Reply Share with Facebook
post #3 of 8 Old 09-21-2011
Senior Member
 
RichH's Avatar
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 3,385
Thanks: 23
Thanked 141 Times in 131 Posts
Rep Power: 15
 
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.
RichH is offline  
Quote Quick Reply Share with Facebook
post #4 of 8 Old 09-21-2011
Senior Moment Member
 
SloopJonB's Avatar
 
Join Date: Jun 2011
Location: West Vancouver B.C.
Posts: 11,359
Thanks: 59
Thanked 67 Times in 64 Posts
Rep Power: 5
 
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.

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.
SloopJonB is offline  
Quote Quick Reply Share with Facebook
post #5 of 8 Old 09-21-2011
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,517
Thanks: 1
Thanked 49 Times in 49 Posts
Rep Power: 7
 
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.
pdqaltair is offline  
Quote Quick Reply Share with Facebook
post #6 of 8 Old 09-22-2011 Thread Starter
Senior Member
 
L124C's Avatar
 
Join Date: Oct 2007
Posts: 1,398
Thanks: 51
Thanked 3 Times in 3 Posts
Rep Power: 8
 
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.
L124C is offline  
Quote Quick Reply Share with Facebook
post #7 of 8 Old 09-22-2011 Thread Starter
Senior Member
 
L124C's Avatar
 
Join Date: Oct 2007
Posts: 1,398
Thanks: 51
Thanked 3 Times in 3 Posts
Rep Power: 8
 
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.
L124C is offline  
Quote Quick Reply Share with Facebook
post #8 of 8 Old 09-22-2011 Thread Starter
Senior Member
 
L124C's Avatar
 
Join Date: Oct 2007
Posts: 1,398
Thanks: 51
Thanked 3 Times in 3 Posts
Rep Power: 8
 
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
0920111434.jpg  
L124C is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome