EXTERNAL INSULATION FOR STAINLESS STEEL

[rogervm]

I need to external insulate some 316L SS and 304L SS pipes, and I dont know what is the best insulation material for that. Is ok to use Mineral wool? or it is required to use an specific material to insulate stainless steel pipes?

Thanks is advamce ....

 

[ash9144]

Need to specify low chlorides or you can get leaching.

 

[EdStainless]

There is a ASTM spec for insulation with low leachable chlorides, but I can't find the number right now.
If this will be in a place where it can get wet, and the lines are hot, I would suggest that you consider painting them with epoxy before you insulate.


= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[kenvlach]

You haven't given the temperature (max & min) nor the environment (indoors, on an offshore platform?)

If any chance of salt in the atmosphere or insulation plus condensing humidity (during shutdowns), see
SS Insulation
thread378-192069

 

[rogervm]

Thank you very much for your answer. I was reading and may the ASTM you are talking about is ASTM C 795.

I have other two queations related to this matter:

1.- What material are low chlorides? For example can I use Mineral Wool?

2.- What would be the best cover (finishing) for the insulation? Jacket?, with vapor barrier?, breather type mastic?

 

[rogervm]

In this specific case the operating temperature is 13 C for liquid H2S service, and 38 C for vapor H2S service.

This installation is indoor (not heating room) and onshore.

 

[IRstuff]

Seems to me, you're asking the questions backwards. What loss is tolerable? What thickness of material is tolerable?

Only then, can you start asking about materials.

TTFN

FAQ731-376

 

[dcasto]

Why insulate?

If you are insulating for freeze protection, you'll need heat tracing too. Fiberglass, rockwool, foam glas... ok.

Vapor barrier? Depends on the dew point temperature of the air and the temperature of the procress.

Finishing, depends on material and vapor barrier needs.

 

[ash9144]

Electric heat trace is very good for H2S service.

I would be hesitant to put an H2S line inside though. Any necessity for that?

 

[kenvlach]

The freezing point of H₂S is -85.5 C, so unless you have moisture also, maybe forego insulation & heat tracing. Just run a few coils of the line through a thermostated bath at the enduse point.

 

[rogervm]

This particular case is a H2S Vaporizer that will Vaporize (outlet line) the liquid H2s (inlet line).

An evaluation was done to decide that the heat tracing is not required from the process point of view.

The H2S liquid line and the H2S vapor line are 316L, and the shell (bath side) of vaporizer (glycol + water)is 304L.

I have been reading, and I understand that it is required to meet the requirements of ASTM 795, ASTM C 871, ASTM C 692, but I still have some doubts:

1.- Is recommended to paint the stainless steel before to insulate?

2.- What is the best cover for the insulation: SS Jacket, Breather type mastic?.

Thanks.

 

[dcasto]

Those ASTM standards are for testing and assuring the insulation doesn't produce stress corrosion. If you do not use insulation, then you don't need the standards. The 304 SS with glycol will need insulating to keep from personal scaulding or "burns". Here is an insulation that complies with the ASTM std. ROXUL BOARD INSULATION 15080TM RHT 606


You do not have to insulate to protect from scaulding, you can put a screen around the pipe to keep people from touching it and getting hurt.

 

[EdStainless]

I have this nasty feeling about putting H2S into 316L.
Considering the risk if there was a leak, and the cost involved, I would be very tempted to use 2205 for the lines. And I would paint (epoxy, two coats) before I insulated.
I am sorry, but CSCC scares the heck out of me, I see so much of it.
If this is indoors most people would use a plastic or Al jacket, just to prevent casual damage to the insulation.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[dcasto]

I run lots of H2S in 304 or 316 at 700 psig. H2S is really non corrosive, its the water that'll get you.

 

[strider6]

rogervm

It's recommended, better mandatory if you are in Offshore or near the sea with high conc of chloride in the atmosphere, if the operating temperature of the line is in the range 50 - 160 °C in order to avoid any possibility of chloride SCC.
In your case, 15-40°C, indoor and onshore, i don't see the necessity to paint.

Look at the NACE standard:
NACE Standard RP0198, "The Control of Corrosion Under Thermal Insulation and Fireproofing Materials—A Systems Approach"

http://www.nace.org/nacestore/assets/freestandardsreports/RP019804.pdf

Is pure H2S or H2S + water or something else?

hope this help

regards
Strider

http://www.corrosionist.com

 

[rogervm]

Thanks to everyone for your valuable answers.


Answering to Strider6,

It is pure H2S.

 

[rogervm]

Answering to dcasto

In fact we are insulating the shell (bath side) of vessel because we are heating the glycol + water with an electric coil and it is necessary to conserve the heat inside the vessel to vaporize the H2S (piping coil of H2S vaporizer).

Thanks.

 

[SJones]

Roger,

It looks like you need a bit more guidance on insulation. The best standard for you to look at is the Dutch CINI Manual if you can get hold of it.

CINI
Stichting Isolatie Nederlandse Industrie
Ceintuurbaan 182
1403 AK Bussum
The Netherlands T: +035 6920225
F: +035 6920225

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/