For the service of sour gases or other Hydrogen Sulfide bearing hydrocarbon fluids. PSN offers NACE valves made of component materials specially heat treated and hardness-controlled in conformity with NACE MR0175 Stardard.
Typical NACE material configuration is shown below for PSN cast steel gate valves. A note should be taken on the fact that NACE hardness requirement conflicts with the one of valve seating surface specified by API 600, Table 3. PSN NACE steel valves are available only at your option.

Valve Part	ASTM Specification	NACE Hardnes	API 600 Hardness
Body/ bonnet	A216 WCB	HRC 22(237 HB)	250 HB*
Disc	A216 WCB or A276 410
Seat	***13Cr deposit or A276 410		-
Gland	***A276 410		275HB  200HB
Stem			-
Lantern ring			250HB
Bonnet bush			250 HB*
Body seat ring
Bonnet bolt	A193 B7	-	-
	A193 B7m**	HRC22
Boneet nut	A194 2H	-
	A194 2HM**	HRC22

* Hardness differential of 50 HB is required between the seats.
**Only when specified.
***Double tempered (Three step process)