Incoloy 800, 800H, and 800HT Flanges

Incoloy 800, 800H, and 800HT Flanges Supplier in Mumbai, India

Nicorex Alloys is an ISO 9001 and ISO 14001 certified trusted supplier of Incoloy 800/800H/800HT flanges in Mumbai, India. We provide these flanges manufactured in accordance with ASTM B564 / ASME SB564 standards for forgings.

These Incoloy 800-series flanges are designed for high-temperature service and resist carburisation, oxidation, and sulfidation in demanding process environments. All three grades use the same nickel–iron–chromium base chemistry (about 32% Ni, 21% Cr, 46% Fe), but they differ in carbon content, aluminium and titanium levels, and controlled grain size. These differences give each grade specific advantages in high-temperature creep and stress-rupture performance. Because of this optimised design, Incoloy 800-series flanges are often the most economical nickel alloy choice for high-temperature process piping, delivering long-term strength and reliability at a much lower cost than premium Inconel or Hastelloy grades. The main variants are Incoloy 800 (UNS N08800), 800H (UNS N08810), and 800HT (UNS N08811). All three grades are supplied as forged flanges. In the annealed condition, Incoloy 800 has a minimum tensile strength of 520 MPa (75 ksi), while 800H and 800HT have 450 MPa (65 ksi). The slightly lower room-temperature strength of 800H/800HT is deliberate, as a coarser grain structure improves long-term creep performance at high temperatures. Available flange types include weld neck (WNRF), slip-on (SORF), blind (BLRF), socket weld (SWRF), threaded, and lap joint.

Standard sizes range from NPS 1/2″ to 24″ and up to NPS 60″ in larger series, with pressure classes from 150 to 2500. Typical end-use industries include petrochemical, power generation, heat treatment, and nuclear.

Incoloy 800/H/HT Flanges Specifications

Key specification details for forged Incoloy 800, 800H, and 800HT flanges, including grades, sizes, pressure classes, and available facing options:

Specification	ASTM B564 / ASME SB564
Dimensional Standards	ASME B16.5, B16.47, MSS SP-44, EN 1092-1, JIS B2220
Flange Types	WNRF, BLRF, SORF, SWRF, Threaded, Lap Joint
Size (ASME B16.5)	NPS 1/2” to NPS 24”
Size (ASME B16.47)	NPS 26” to NPS 60”
Pressure Classes	150, 300, 600, 900, 1500, 2500
Face Types	RF, FF, RTJ

Understanding the Difference: Incoloy 800 vs 800H vs 800HT

Incoloy 800, 800H, and 800HT share a Ni-Fe-Cr base but differ in carbon, Al+Ti, and grain-size-controlled creep:

Parameter	800	800H	800HT
Carbon	0.10 max	0.05–0.10	0.06–0.10
Al+Ti	0.30–1.20	0.30–1.20	0.30–1.20
Grain Size	No requirement	ASTM No. 5 or coarser	ASTM No. 5 or coarser
Max Service Temp	~593°C (1100°F)	~900°C (1650°F)	~900°C (1650°F)
ASME BPVC	Section VIII	Section I & VIII	Section I & VIII
Key Advantage	Best weldability	Better creep than 800	Best creep/rupture

Below 593°C, standard 800 flanges are sufficient. For steam reformer furnaces, ethylene cracker piping, or any service above 593°C, specify 800H or 800HT.

Chemical Composition of Incoloy 800/800H/800HT Flanges

Standardised chemical composition of Incoloy 800-series flanges, as per ASTM B564 are provided in the following table:

Grade	Ni	Cr	Fe	C	Al	Ti	Al+Ti	Mn	Si	S	Cu
Alloy 800	30.0–35.0	19.0–23.0	39.5 min (bal)	0.10 max	0.15–0.60	0.15–0.60	0.30–1.20	1.5 max	1.0 max	0.015 max	0.75 max
Alloy 800H	30.0–35.0	19.0–23.0	39.5 min (bal)	0.05–0.10	0.15–0.60	0.15–0.60	0.30–1.20	1.5 max	1.0 max	0.015 max	0.75 max
Alloy 800HT	30.0–35.0	19.0–23.0	39.5 min (bal)	0.06–0.10	0.25–0.60	0.25–0.60	0.85–1.20	1.5 max	1.0 max	0.015 max	0.75 max

The key chemistry differences: 800H controls C at 0.05–0.10% for better creep. 800HT raises Al+Ti to ≥0.85%, strengthening grain boundaries for the highest stress rupture in the series.

Mechanical Properties of Incoloy 800/H/HT Flanges

Mechanical performance of Incoloy 800HT flanges in solution-annealed condition, specified and tested according to ASTM B564 forging requirements:

Property	Tensile (min)	Yield (min)	Elongation (min)
800 (N08800)	520 MPa (75 ksi)	205 MPa (30 ksi)	30%
800H (N08810)	450 MPa (65 ksi)	170 MPa (25 ksi)	30%
800HT (N08811)	450 MPa (65 ksi)	170 MPa (25 ksi)	30%

800H and 800HT show lower room-temperature strength than 800. Coarser grain (ASTM No. 5 or coarser) reduces tensile values but gives far better creep rupture. At 816°C (1500°F), 800HT has approximately 30% higher 10,000-hour stress rupture strength than standard 800.

Incoloy 800/800H/800HT Equivalent International Grades

Global equivalents for Incoloy 800, 800H, and 800HT, listing corresponding UNS, Werkstoff, EN, and JIS designations:

Standard	UNS	Werkstoff	EN	JIS
Alloy 800	N08800	1.4876	X10NiCrAlTi32-21	NCF 800
Alloy 800H	N08810	1.4958	X5NiCrAlTi31-20	NCF 800H
Alloy 800HT	N08811	1.4959	X8NiCrAlTi32-21	NCF 800HP

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Available Types of Incoloy 800 Series Flanges

All three grades are available in the same forged flange types per ASTM B564:

Incoloy 800 Weld Neck Flange (WNRF)

Incoloy 800HT Blind Flange (BLRF)

Incoloy 800H Slip-On Flange (SORF)

Alloy 800 Socket Weld Flange (SWRF)

Incoloy 800HT Threaded Flange

Incoloy 800 Lap Joint Flange

Nickel Alloy 800H RTJ Flange

Inconel 800 Orifice Flange

Inconel 800HT Spectacle Blind Flange

Incoloy 800 Reducing Flange

Pressure-Temperature Ratings for Incoloy 800-Series Flanges

Incoloy 800-series flanges (800, 800H, 800HT) manufactured per ASTM B564 to ASME B16.5 are classified under Material Groups 3.6 and 3.15, with maximum allowable working pressures (psig) decreasing as service temperature rises from ambient to 1000°F (538°C) across Class 150 through 2500 ratings.

Temp °F (°C)	Incoloy 800 · Group 3.6						Incoloy 800H / 800HT · Group 3.15
Temp °F (°C)	150	300	600	900	1500	2500	150	300	600	900	1500	2500
-20 to 100 (38)	275	720	1,440	2,160	3,600	6,000	230	600	1,200	1,800	3,000	5,000
200 (93)	240	620	1,245	1,865	3,110	5,185	200	520	1,035	1,555	2,590	4,315
300 (149)	215	560	1,120	1,680	2,805	4,675	180	475	950	1,425	2,375	3,955
400 (204)	195	515	1,025	1,540	2,570	4,280	165	435	865	1,300	2,165	3,610
500 (260)	180	475	950	1,425	2,375	3,955	150	400	795	1,195	1,990	3,315
600 (316)	170	450	900	1,350	2,250	3,750	145	380	755	1,135	1,890	3,150
700 (371)	160	425	850	1,275	2,125	3,540	135	360	720	1,080	1,795	2,995
800 (427)	150	395	790	1,185	1,975	3,290	125	335	665	1,000	1,665	2,775
900 (482)	130	350	695	1,045	1,740	2,900	110	295	590	885	1,475	2,455
1000 (538)	105	280	555	835	1,390	2,315	85	230	455	685	1,140	1,900

All pressures in psig per ASME B16.5. Flanged end ratings terminate at 1000°F (538°C). Class 400 omitted. Linear interpolation permitted between listed temperatures. Always verify against the current edition of ASME B16.5 for final design.

Industrial Applications of Incoloy 800 Series Flanges

Incoloy 800 series flanges deliver reliable high-temperature performance across petrochemical, power, furnace, chemical, and nuclear applications worldwide.

Petrochemical Processing: Ethylene cracker radiant coil outlet flanges, steam methane reformer (SMR) pigtail connections, and transfer line exchanger (TLE) inlet flanges.
Power Generation: Superheater outlet header flanges, reheater manifold connections, and economiser piping. ASME Section I approved.
Heat Treatment & Industrial Furnaces: Furnace muffle connections, retort flanges, radiant tube outlets, and quench headers.
Chemical Processing: Nitric acid condenser flanges and sulfuric acid heat exchanger connections.
Nuclear Energy: CANDU reactor fuel channel and heat exchanger flanges.

How to Order Incoloy 800H Flanges from Nicorex Alloys

To order Incoloy 800/H/HT Flanges, provide these following details:

Flange Type: WNRF / BLRF / SORF / SWRF / RTJ
Size: NPS and Schedule (½" to 24"+)
Pressure Class: 150 / 300 / 600 / 900 / 1500 / 2500
Face Type: RF / FF / RTJ / T&G
Material Grade: 800 / UNS N08800 / 800H / UNS N08810 / 800HT / UNS N08811
Quantity: Number of pieces or kg
Standard: ASME B16.5 / B16.47 / ASTM B564
Documentation: MTC 3.1/3.2, PMI, Grain Size Report, TPI Certificate
Delivery: Domestic

Custom sizes available – Contact us today for a quick quote on Incoloy 800 flanges.

Frequently Asked Questions

What is the actual difference between Incoloy 800, 800H, and 800HT?

All share the same Ni-Fe-Cr base. 800H controls C at 0.05–0.10% with ASTM No. 5 or coarser grain for better creep. 800HT adds Al+Ti ≥0.85% for the highest stress rupture. Use 800 below 593°C; 800H/HT above.

Can Incoloy 800HT replace 800H in all applications?

Not always. 800HT has slightly lower weldability due to higher Al+Ti. For extensive welding, prefer 800H. Where maximum creep rupture is primary, 800HT is superior.

What is the Maximum Service Temperature for Incoloy 800HT Flanges?

ASME BPVC allows design temperatures to approximately 898°C (1650°F) for 800HT.

Is Incoloy 800 Resistant to Sulfidation at high temperatures?

Yes. The 19–23% Cr content provides good sulfidation resistance, superior to 300-series stainless steels in refinery furnace environments with sulphur-bearing process gases.

Does Nicorex Alloys Supply Incoloy 800HT Flanges for Ethylene Cracker Service?

Yes. 800HT flanges for ethylene furnace outlet piping and transfer line systems per ASTM B564 with grain size verification and full compliance documentation are available.