Bolts Designed to be Rapidly Corrode in Seawater

[Ping6809]

I'm working on a project where we have an instance where we want some bolts to quickly distinegrate to nothing in seawater over the course of a few hours. I've heard of bolts like this that immediatly start to seem to boil the seawater upon contact. What type of bolt should I use for this job?

 

[unclesyd]

If it is worth retrieving the way to go is the Fiobouy. This equipment works like a charm.

http://www.fiomarine.com/index.html

http://www.rsaqua.co.uk/uploads/pdfs/Products/Fiomarine/Introducing_Fiobuoy.pdf

 

[metengr]

Few hours might be idealistic. Looks like magnesium bolts coupled with steel based on an excerpt from the following report....

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD404524&Location=U2&doc=GetTRDoc.pdf

An example of electrochemical attack on one of the
magnesium bolts is seen in Figure 3 where the nut, washers and plates
are steel and the result of 24 hours immersion in sea water in the
laboratory is demonstrated by the corroded magnesium bolt. Complete
disintegration of the bolt took place in 72 hours.

 

[PeterStock]

When I was in school years ago, a former student was in the business of makeing corrosion release systems for lobster pots. This used a link that would hold the bouy to the pot. The idea was you desided when you would be back to check on your pots and picked the correct link, it would corrode to the point that it broke and the bouy rose to the surface for you to pickup. I do not know if he is still in business (I believe there was some environmental concern).

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[MJCronin]

These work well....

http://www.psemc.com/ebolts.htm

No problem with "timing" for these babys......

 

[Ping6809]

I actually had looked into exploding bolts as a possibility for releasing my underwater mooring system. Another possibility I investigated was 90% Magnesium 10% Iron alloy bolts. These seemed to work well and you could size the magnesium in such a way to get the corrosion down to a release in a matter of tens of minutes. The problem with that solution was too much red tape in "fire hazards" of machining the magnesium. My most successful avenue has been in been in distinigrating a 22 AWG NiCrFe wire capable of holding 300 lbs with a jolt of electricity.