Inconel is a registered trade name of Special Metal Alloys Corporation.
Inconel alloy 625(UNS 06625/W.Nr.: 2.4856) is a nickel-chromium-molybdenum alloy with an addition of niobium that acts with the molybdenum to stiffen the alloy’s matrix and thereby provide high strength without a strengthening heat treatment. The alloy resists a wide range of severely corrosive environments and is especially resistant to pitting and crevice corrosion.
The high molybdenum content makes this alloy very resistant to pitting and crevice corrosion, and niobium acts to stabilize the alloy against sensitization during welding, thereby preventing subsequent intergranular cracking. Also, the high nickel content provides freedom from chloride ion stress-corrosion cracking.
The outstanding and versatile corrosion resistance of INCONEL alloy 625 under a wide range of temperatures and pressures is a primary reason for its wide acceptance in the chemical processing field.
It is used in sour hydrocarbon, high pressure and high temperature applications. Where production gas is sour and wet containing chlorides, Inconel 625 is a suitable material for this application.
Following is a typical specification for class 1500 Inconel Alloy 625 piping 226 barg @ 103° C
Pipes
- 1½" & below------ Sch 80s ASTM B 444 UNS No 6625 Gr 1 seamless or SAW - 100 % radiography.
- 2" thru 4" ----------- Sch 40s ASTM B 444 UNS No 6625 Gr 1 seamless or SAW - 100 % radiography.
- 6" thru 10" --------- Sch 80s ASTM B 444 UNS No 6625 Gr 1 seamless or SAW - 100 % radiography.
Fittings
- 1½" & below------ Socket Weld forged fittings to ASTM B 564 UNS No 6625 material.
- 2" thru 10" --------- Butt weld fittings to ASTM B 366 Gr WPNCMC, S or WX material, Wall thickness same as pipe.
Welded wrought fittings WX must be 100 % radiographed after forming.
Flanges
- 1½" & below------ Socket Weld RTJ flanges to ASTM B 564 UNS No 6625 material.
- 2" thru 10" --------- Weld Neck RTJ flanges to ASTM B 564 UNS No 6625 material.
Gaskets
- Octogonal Ring Joint, Inconel 625, per ASME B 16.20, 1500 Lbs rating, 210 HRB maximum hardness.
Minimum hardness of flange ring joint groove facing will 230 HRB.
More information for Inconel Alloy 625 can be obtained from this link Special Metal Alloys