No registration or passwords; no pop-up ads -- just aloha, fun, & answers.
(as an eBay Partner & Amazon Affiliate earns from qualifying purchases).
Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Advertise
 
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989



-----

EN plating for 25 year seawater service




What EN plating and thickness would be recommended for a 25 year life of a component immersed in seawater at 4 °C. The component would be a low carbon free machining mild steel.

Can you also recommend an accelerated test method to evaluate the component life.

Kevin Raymond Green
Subsea control valve manufacturer - Gt Yarmouth, Norfolk, England
2004



simultaneous replies

Theoretically, the corrosion of 10-1/2% phosphorous EN is almost zero immersed in sea water, but 25 years is a lot. I don't know of any lab test or experiment that can predict over such a long term. Besides corrosion, there will be erosion issues to deal with and those depend on water velocity, presence of sand, adhesion of foreign unknown matter just to name a few.

Guillermo Marrufo
Monterrey, NL, Mexico
2004



2004

Oil field and subsea components are typically plated with 75 microns of a high phosphorous type (>11%P) EN. However, it is unlikely that you will obtain a "perfect" coating without any pores, that will provide complete protection for 25 years, especially on free machining steel. You should expect that small pores in the coating will result in some rust spots. Usually, in seawater the pores become plugged with rust and stop growing after a few months. Electroless nickel coated components have been used successfully for periods greater than 10 years in seawater.

Ron Duncan
Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.



Wow, you are asking for what I would think was close to impossible and then you want to make it out of the cheapest material possible. Leaded steel is begging for a plating problem and occasional failure! To stand any chance of lasting 25 years it would probably be a high P EN with a minimum of 0.002 per side. I suspect that you are also going to have a galvanic couple which means that something is going to corrode over a long period. More gloom, there is no accelerated testing that will have any direct relationship to how long it will last in your use. Accelerated testing is a quality control test and not a functional use test.

James Watts
- Navarre, Florida
2004


Than you for all of the responses so far they are much appreciated. Would a coating of a nickel PTFE composite plating perform any better than a high Phos EN plating.

Kevin Green
- England
2004


Theoretically no, on the contrary, but it may happen that a composite plated object outperforms another with plain EN only because it was done by a more experienced and professional plater.

Guillermo Marrufo
Monterrey, NL, Mexico
2004




(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact  -  Privacy Policy  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"