Incoloy 800 Flanges (ASTM B564 UNS N08800)

1. General Introduction

Incoloy 800 flanges (pipe flanges) refer to forged flanges manufactured to ASTM B564 according to the dimensional standards of ASME B16.5. Incoloy 800, also known as Alloy 800 or UNS N08800, is an iron-nickel-chromium alloy with good creep & stress-rupture strength and excellent resistance to oxidation, sulfurization and carburization in high-temperature services. It also resists corrosion by many aqueous environments. The forged Incoloy 800 flanges can be used in applications with temperatures up to 816°C while maintaining a stable, austenitic structure during prolonged exposure to high temperatures. The material is widely utilized in processing piping, heat exchangers, heating element sheathing, petrochemical pipeline(especially for heavy oil) and nuclear power plant, etc.

2. Pressure-Temperature ratings for Incoloy 800 flanges

Temp. °C	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
-29~38	19.0	49.6	66.2	99.3	148.9	248.2	413.7
50	18.7	48.8	65.1	97.6	146.4	244.0	406.7
100	17.5	45.6	60.8	91.2	136.9	228.1	380.1
150	15.8	44.0	58.7	88.0	132.0	219.9	366.6
200	13.8	42.8	57.1	85.6	128.4	214.0	356.7
250	12.1	41.7	55.7	83.5	125.2	208.7	347.9
300	10.2	40.8	54.4	81.6	122.5	204.1	340.2
325	9.3	40.3	53.8	80.6	120.9	201.6	336.0
350	8.4	39.8	53.0	79.5	119.3	198.8	331.3
375	7.4	38.9	51.6	77.6	116.5	194.1	323.2
400	6.5	36.5	48.9	73.3	109.8	183.1	304.9
425	5.5	35.2	46.5	70.0	105.1	175.1	291.6
450	4.6	33.7	45.1	67.7	101.4	169.0	281.8
475	3.7	31.7	42.3	63.4	95.1	158.2	263.9
500	2.8	28.2	37.6	56.5	84.7	140.9	235.0
538	1.4	25.2	33.4	50.0	75.2	125.5	208.9
550	-	25.0	33.3	49.8	74.8	124.9	208.0
575	-	24.0	31.9	47.9	71.8	119.7	199.5
600	-	21.6	28.6	42.9	64.2	107.0	178.5
625	-	18.3	24.3	36.6	54.9	91.2	152.0
650	-	14.1	18.9	28.1	42.5	70.7	117.7
675	-	10.3	13.7	20.5	30.8	51.3	85.6
700	-	5.6	7.4	11.1	16.7	27.8	46.3
725	-	4.0	5.4	8.1	12.1	20.1	33.6
750	-	3.0	4.0	6.1	9.1	15.1	25.2
775	-	2.5	3.3	4.9	7.4	12.4	20.6
800	-	2.2	2.9	4.3	6.5	10.8	18.0
816	-	1.9	2.5	3.8	5.7	9.5	15.8

*All the forged Alloy 800 flanges shall be annealed.

3. Chemical composition requirements for Incoloy 800 (UNS N08800).

Chemical Composition of Incoloy 800

Element	Content, %
Nickel (Ni)	30.0~35.0
Copper (Cu)	0.75 max
Iron (Fe)	39.5 min
Manganese (Mn)	1.5 max
Carbon (C)	0.10 max
Silicon (Si)	1.0 max
Sulfur (S)	0.015 max
Chromium (Cr)	19.0~23.0
Aluminum (Al)	0.15~0.60
Titanium (Ti)	0.15~0.60

*Chromium additions improve sulfidation resistance while aluminum and titanium allow strengthening through precipitation hardening (age hardening). Nickel content not only improves the fatigue strength and high-temperature performance(especially in reducing environments) but also inherently resists to reducing corrosion, both acid and alkali. Thus, Incoloy 800 has better resistance to reducing corrosion than common austenitic stainless steels.

4. Mechanical requirements for Incoloy 800 forgings.

Mechanical Properties of Incoloy 800

Tensile Strength, min ksi (MPa)	Yield Strength, min ksi (MPa)	Elongation min. %
75 (517)	30 (207)	30

*The forgings shall take ultrasonic test or liquid penetration inspection. Liquid penetration inspection is not applicable to forgings with hot finished surface.