2mm thickness you have listed there is not sufficient to prevent any mechanical damage.  None.  In fact for a riser design I would not have confidence in a 2 mm wall steel pipe jacket.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

Quote:

corrosion and mechanical damage

Please clarify: mechanical damage to the riser or mechanical damage to the coating? As already pointed out, no anti-corrosion coating is going to offer any serious mechanical protection to the pipe.  

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
 

Sorry,
i was not clear.

2mm shall give protection against corrosion of steel and shall prevent mechanical damages to the coating:
the riser during its life shall not show parts where the steel is exposed. This condition, i think, is necessary in the splash zone.

Thanks for support.

 

Basically I think 2mm of anything = nothing.  
Even if it was 2mm steel in dirty water currents, I'd still have doubts.  Have you looked at 2mm on the ruler?  These days I need glasses to see it.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

What lifetime?  5 years? 10, 25?  

It sounds like you probably need to use an artist's #2 paint brush to apply it.  One-pass of a spray can gives me slightly more paint than that in some areas.  Sorry, you'll never convince me 2mm >= 25.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

I don't think that you'll find too many people willing to jump away from polychloroprene, EPDM, or monel sheathing on a riser. A 2 mm nominal DFT coating is probably in the atmospheric zone.

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
 

In fact i have doubts on this solution: 2mm of solid polyurethane tar free.
This is the solution proposed to me by our consultant.
Design life is 30 years.

I'm not an expert on coating material but it sounds me not reliable.

I'm pushing for a 20 mm of polychloroprene that is the solution i know and about wich i have references from other projects.
But consultant told me this is a widely used system.
Is he right?
 

"Widely" meaning exactly what?  Would "widely" include onshore pipe paint inside buildings?  I wouldn't even use 2 mm in the splash zone, or anywhere below the bottom deck for that matter.  If anything "bumps" it hard, it'll be there, or on the top deck.  

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

Widely used for jackets perhaps?

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
 

Widely used for risers!!!

Ok. You confirm my doubts.
Moreover I did not have any reference with this system from consultant after my request.

In conclusion, i think to stay in my position: >20 mm of polychloroprene.

Thanx all.

Just for information.

The final selection agreed with consultant:

20 mm of polyurethane mixture.

Not professing specific expertise here but I have noticed there is a book or two that discusses some aspects of these sorts of installations (e.g. http://books.google.com/books?id=3QqX-HZzi-MC&pg=PA85&lpg=PA85&;dq=concrete+coated+risers&;source=bl&ots=q-noQq6RWs&sig=5GsRaQ8zlWaLaHKFzQXkvshhGyY&hl=en&ei=bDcgSoGSPIq_twextL3CBg&sa=X&oi=book_result&ct=result&resnum=5 ).  All have a good weekend.   

In addition to above discussion, I have other question regarding splash zone coating. Is Polypropylene (4LPP) is suitable for splash zone and above splash zone area? Is it resistant to UV?

ek4putr4,
I noticed noone had yet responded to your sort of add-on inquiry.  I think it can be said that polymers/plastics in general are affected by UV, and for mechanisms you might refer to any applicable portions of the references mentioned in I suspect other searchable threads e.g. http://cr4.globalspec.com/thread/37780.  As far as polypropylene, this is of course a common plastic used in applications virtually all are familiar with, e.g. for rope etc. (and while it of course is likely not be the same formulation as the coatings you are dealing with, most of us have however seen what happens to such ropes in longtime exposure).  This of course does not necessarily mean that you wouldn't get some serviceability/utility from such coatings in even a rough environment like "splash zone" however, as it is claimed the basic material can of course be compounded with additives that reportedly resist such degradation (e.g. see http://www.inplexllc.com/material.htm).  I noticed there was also a very current thread on another forum at http://www.eng-tips.com/viewthread.cfm?qid=246662&page=1 ,having to do it appears with some sort of composite PP coating system.
Maybe you will get other responses that will be more helpful from some folks who have actually used such coatings for similar service.
  

For what specific items is '4LPP' being considered as a coating system?

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
 

This is taken from NORSK M001 - Material Selection
http://www.standard.no/PageFiles/1194/M-001.pdf

"Splash zone protection
Splash zone protection depends on the maintenance philosophy and the environmental conditions at the
site.
For North Sea use, the following maintenance philosophy applies: Coating on structural steel will not be
repaired during the lifetime. Coating on risers will be repaired within 2 years after a damage exposing bare
steel. Then the corrosion protection for permanently installed equipment shall consist of coating and
corrosion allowance calculated as follows:
• corrosion allowance for carbon steel in the splash zone with thin film coating: minimum 5 mm. For design
lives more than 17,5 years: Corrosion allowance = (design life – X years) x 0,4 mm/year, where X = 5 for
thin film coating and X = 10 for thick film coating. Thick film coating is understood as an abrasion resistant
coating with thickness of minimum 1000 micron and applied in minimum 2 coats or layers;
• corrosion allowance for carbon steel and SM13Cr risers: minimum 2 mm in combination with minimum 12
mm vulcanised chloroprene rubber. At elevated temperature the corrosion allowance shall be increased
by 1 mm per 10 °C increase in operating temperature above 25 °C;
• stainless steel risers: minimum 12 mm vulcanised chloroprene rubber."

hope this help

S

Corrosion Prevention & Corrosion Control