SS Condensate Pipe 2

[Jeffrey W]

We are upgrading our condensate piping from CS to SS. The condensate piping is stainless steel that is being insulated. Do we need to paint the SS piping to address Chloride stress corrosion cracking concerns? The condensate piping will be above the critical stress corrosion cracking temperature of 140F, and uncoated stainless steel under insulation leaves the potential for chlorides to build up on the surface of the piping under the insulation.

Condensate operating temperature 441F.

 

[LittleInch]

Please choose ONE forum and delete the other posts or else they will just vanish on you. This ones pretty good for your question.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

The answer to your question may depend on the particular installation which you have not posted. Is this installation located on a coastal oil rig or in a power plant? What is the type of insulation?

 

[Jeffrey W]

It will be installed at a Chemical plant, and the entire piping system will be exposed to the elements.

Insulation: 3" Thick Foamglas

 

[Latexman]

Near the coast, or inland?

Good Luck,
Latexman

 

[Jeffrey W]

inland

 

[SJones]

API RP 572 - degradation mechanism CUI
API RP 583
NACE SP0198
EFC Publication 55

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

What does the plant make?
Does the site use any Cl?
You don't say but we will presume light gage 304 or 316 SS.
If there is any environmental Cl (natural or otherwise) then paint.
While the risk of SCC at ambient temp is low there are some Cl compounds that can form which are much more aggressive.
Compared to a high-quality coating application you might want to look at the cost of doing this in sch5 2205 duplex.

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P.E. Metallurgy, consulting work welcomed

 

[SJones]

The critical temperature range is considered to be 50 to 175 deg C. At 227 deg C, the CUI (External SCC) risk might be considered lowered dependent upon the quality of the insulation materials, and the nature of the external environment. The main consideration is the potential for cycling through the high risk temperature range which could cause wetting, drying, and salt concentration. If you are looking for peace of mind, and low maintenance, liquid paint systems might not be the optimum corrosion protection solution: they get damaged, they degrade significantly over time, and they are unable to apply cathodic protection to exposed stainless steel substrate areas. For that reason, many oil and gas operators have turned to either aluminium foil wrapping, or thermal spray aluminium as the corrosion protection solution.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[georgeverghese]

At the OpCo I used to work in, standard solution is to apply TSA (thermal spray Al) on SS316 piping before insulating. For added insurance against CUI, use foamglass insulation to minimise risk of external water ingress.

 

[EdStainless]

TSA, foamglass, and good rain covers (that are well maintained and have drains) will be a great choice.

I have seen a number of cases where there was CSCC failure at ambient temperature.
They all involved lots of Cl (process leaks or near coast) and lots of organics (windblown from local woods and fields) which formed chloramines.
One of them was inside a building where the piping never saw rain to wash it.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed