Hastelloy type for hydrochloride acid and sodium hydroxide

How severe is the caustic? In general Ni alloys don't like high pH, especially if the conditions are reducing.
I will try to find you some corrosion data for "C" type alloys in in caustic.

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Corrosion never sleeps, but it can be managed.

EdStainless,

Thanks for your quick repley. The conditions are as follows:
HCl 30% 5 barg @ 60 deg C / NaOH 22% 5 barg @ 60 deg C.

I would probably go for a PFA/PTFE lined sample valve. We use a lot Manufacturers whe have used CRP-Flexrite, Technova, Halwachs. Can get a bit pricy but do the job. They have some good safety features most of them will design around a standard valve for unusual duties.

Good luck.

Biggy

According to Philip A Schweitzer the following Hastelloy grades are resistant to both sodium hydroxide as well as hydrochloric acid: (Temperature degree Fahrenheit). The tabled value indicates the resistance is "good".
"Good" is defined as <20 mils/year.

HCl Dilute 20% 35% 38% 50%
Hastelloy B/B-2 180 220 200 140 80
Hastelloy C/C-276 160 150 140 140 80

NaOH 10% 15% 30% 50% 70% Conc
Hastelloy B/B-2 230 210 250 250 220 200
Hastelloy C/C-276 230 210 210 210 220 120