Advice for HCL & Cl SCC

[Normankhan]

Hello All

I require some feedback from you guys. very soon we are going to shift from H2S04 to 20%HCL (Dilute) usuage in one of our equipment for making end product.I have two concerns regarding Material of construction, one is for HCL itself and CL (chloride ions). As chloride itself might cause Cloride SCC. Currently we are using following materials as MOC in our equipments and piping for H2SO4 but will use same once shifted to HCL under operating temp: say 85 C or in worst case say 100 C with PH=4(acidic as max value) and chlordie%=1.6-2.0%.

-Piping MOC: Glass reinforced FRP Epoxy resin,CPVC,SS-316L,C.S A-106 Gr-B
-Equipments including Tanks and agigtators:C.S Rubber/lined,Alloy 20,SS-316L,SS-304,SS-310,FRP,Chem flake chemical coating.

I would like to know that under above operating conditions will these Materials would be compatible for HCL and resisting chloride SCC???

kindly provide some details.

Thanks
Norm

 

[micalbrch]

I'm not a corrosion expert but I'm sure that SS-316L and SS-304 will not last. HCl is worse for standard stainless steels than H2SO4. 1.6 to 2 % chlorides should be o.k. for SS-316L and SS-310 but most probably not for SS-304.

Rubber lining C.S. might be good, even for HCl but that depends upon the kind of rubber.

 

[strider6]

you've severeal different materials, and the operating conditions are very demanding
i suggest you to make a careful materials evaluation..

have a look at this doc from NIDI:

http://www.corrosionsource.com/technicallibrary/nidi/literature/pdf/10020.pdf

hope this help

S.

Corrosion & Rust Prevention Control

 

[EdStainless]

If you want to stay with metals you will need to go up the food chain quite a ways.
Are there any metals in this solution. If there is Fe or Cu you need to look at Ti.
If not then a 6% Mo superaustenitic or a superduplex should get you there.

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Plymouth Tube

 

[rodneybennet]

The operating conditions requires rigorous material evaluation.

The preferable material is most probably reinforced epoxy, but exact epoxy and laminate build-up depends on the lifetime requirement, since the composite will defitenly age in the circumstances given.

More quantitive support can be acquired using the CheFEM simulation device (more info at

http://www.composite-agency.com/CheFEM.htm).

Kind Regards,
Rodney

 

[George77577]

Hands down best material is Novolac Vinyl Ester such as Ashland Derakane 470-350 with 200 mil corrosion barrier, double carbon veil. 20% HCL good to 110C, up to 25% 100C, 30% 95C. Write a good specification and choose your fabricator carefully and will last for 25 years. Carbon veil is much more resistant to blister formation.