Super Deuplex or Inconel Grade 1

[mechmos]

I have been asked by someone in my company to look into what grade of either super duplex or inconel they will need for pipe for pumping 10%HCL at 90 degrees centigrade.

Any advice as I have not had experience of either of these before?

Greatly appreciated.

Mechmos

 

[Metalguy]

Hast. B. Big $$$$$$.

"When the eagles are silent, the parrots begin to jabber."
Winston Churchill

 

[EdStainless]

You need to know exactly what trace impurities are in it. If thetre are NO oxidizing agents (Fe III) then you should look into using B-2. This is a Ni-Mo alloy. It is very expensive and it was delevoped for hot acid service.
IF you do have oxidizing ions present then I am not sure what options you have. I don't believe that a "C" type alloy can handle this temp.

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Rust never sleeps
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[unclesyd]

The aforementioned Hastelloy B, now B-2, is highly sensitive to Ferric Iron Concentration, as low as 10 ppm.

Comeback with a little more information about your process especially the acid purity.

You might have to go to something like this.

http://www.resistoflex.com/thermalok_process.htm

 

[EdStainless]

Heck, B-2 even shows higher corrosion rates on airiated acid.
This temp is nothing to take lightly.

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

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

 

[joeswoes]

You must have high pressures, as this is a slam dunk for composite pipe

 

[EdStainless]

Good idea.

http://www.smithfibercast.com/main.htm

This is right at the temp limit, but even using heavy gage composite pipe with continous support it will be a lot less money than alloy.

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

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

 

[moltenmetal]

As I always say: you should never settle for corrosion resistance when you can have corrosion immunity.

Use lined pipe, unless pressures are very low, in which case FRP is a good choice as mentioned, especially at linesizes 3" and above. PVDF- or PTFE-lined will be fine down to the smallest linesize available (1"). You get the disadvantage of more potential leakage points since every tee, elbow etc. is flanged, but you also get the benefit of more mechanical robustness and greater pressure/temperature handling relative to FRP pipe.

 

[EdStainless]

The concern that I have with lined pipe in this application is that any leak will become catastrophic. If this were colder service then I would like the lined option. Creep of liners and failures at flanges are serious risks at the higer temps.

If you go with FRP in this service make sure that you validate the joining method. If you are glueing you must test glued joints in hot acid to make sure that they will hold up.

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

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

 

[TomEun]

Please find the followings.

1.

http://www.nickelinstitute.org/index.cfm/ci_id/3154/la_id/1/tecArticle/1

2. API TR938C-2005 Use of DSS in the Oil Refining Industry

 

[stanweld]

Zirconium has been used in similar applications but it too is susceptible to higher corrosion rates in oxygen and iron contaminated solutions. If you think Alloy B2 is expensive you'll really get an eye opener with Zirconium costs. Even more so with Tantalum.

Glass lined carbon steels have been used in similar applications for vessels but I don't know any glass lined steel pipe manufacturers for pipe.

I used polyvinylidene flouride lined Alloy 625 pipe and vessels (US GOV Project)in a similar application many years ago. Lesser alloys were not considered due to Ed's commentary regarding catastrophic failure. Design Life of the equipment was only 2 years. The equipment did survive its design life.

 

[moltenmetal]

Materials a great deal more hazardous than 10% aqueous HCl at 90 C are handled daily, safely, in teflon-lined carbon steel pipe. With design lives a lot longer than 2 years.

 

[EdStainless]

maybe more hazardous to people, but more hazardous to the pipe? I have seen both HCl and N2SO4 take out pipe due to liner creap at flanges, and the full destruction took a matter of hours.
If the system does not see thermal orpressure cycling, then maybe. Composite is still my first suggestion.

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

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

 

[moltenmetal]

EdStainless: we're not disagreeing. I will always choose corrosion immunity over corrosion resistance. Trying to find a metallic alloy for this service is foolhardy in my opinion.

The correct selection between the two options (FRP and lined metallic piping) depends on a great many factors the OP hasn't listed. Yes, lined metallic piping suffers from the vulnerability you've indicated, amongst others, but FRP piping is not without its pitfalls as well- especially at small linesizes (i.e. 1.5" and 2"). Just as you've seen liner failures leading to rapid loss of containment, I've seen Smith Fibrecast fittings which leak at several hundred locations right out of the box, and carefully assembled and fully cured socket-welded FRP pipe spools which exhibited 90% joint leakage during a hydrotest. Properly designed, tested, installed and monitored/ maintained, both systems can be fit for purpose.