Incoloy 800 Stud Bolts

Incoloy 800 Stud Bolts are precision-threaded fasteners manufactured from UNS N08800, a nickel-iron-chromium alloy designed for long-term service in high-temperature environments. The alloy contains roughly 30–35% nickel, 19–23% chromium, and a balance of iron, giving it stable resistance to oxidation, carburisation, and creep at temperatures up to 900°C. These stud bolts are used on heat treatment equipment, petrochemical furnaces, power plant steam systems, and chemical processing plants where the integrity of the joint must be maintained under continuous heat. Their good corrosion resistance, together with reliable high temperature strength, make them a dependable choice in demanding thermal service.

Price of Incoloy 800 Stud Bolts

UNS N08800 Stud Bolts price varies depending on size, length, thread configuration, certifications required, and order volume. The reference figures below are for guidance in planning.

Approx Price Range

The approximate price of Incoloy 800 Stud Bolts in the Indian market is between Rs. 600 and Rs. 1,250 per kg. Indicative prices and subject to change depending on raw material prices, heat treatment requirements, and current market conditions.

Price Per Unit / Kg

Size	Approx Price Per Piece (INR)
M10 x 50 mm	Rs. 65 – Rs. 130
M12 x 75 mm	Rs. 110 – Rs. 210
M16 x 100 mm	Rs. 200 – Rs. 370
M20 x 150 mm	Rs. 380 – Rs. 680
M24 x 200 mm	Rs. 650 – Rs. 1,100

Factors Affecting Price

Raw material surcharges on nickel and chromium, thread form, annealing requirements, order quantity, third-party inspection scope, and delivery timeline all directly affect the final cost of Incoloy 800 Stud Bolts.

Types of Alloy 800 Stud Bolts

Incoloy 800 Stud Bolts are available in different configurations for different flange assemblies, pressure ratings, and installation methods.

Fully Threaded Stud Bolts
Double-End Stud Bolts
Tap-End Stud Bolts
Continuous Thread Stud Bolts

Specifications of UNS N08800 Stud Bolts

The table below covers the key material and dimensional standards applicable to Incoloy 800 Stud Bolts.

Specification	Details
Material	Incoloy 800 / UNS N08800 / W.Nr. 1.4876
Standard	ASTM B408 / ASME SB408
Thread Standard	ASME B18.2.1 / DIN 976 / ISO 4033
Thread Form	UNC, UNF, Metric Coarse, Metric Fine
Condition	Annealed / Solution Annealed
Hardness	85 HRB max
Length	25 mm to 3000 mm
Diameter	M6 to M100 / 1/4" to 4"
Finish	Plain, Passivated, Xylan Coated

Chemical Properties of Incoloy 800 Stud Bolts

The table below lists the chemical composition of UNS N08800. The controlled carbon, aluminium, and titanium content distinguishes Incoloy 800 from the higher-specification 800H and 800HT variants.

Element	Min (%)	Max (%)
Nickel (Ni)	30.00	35.00
Chromium (Cr)	19.00	23.00
Iron (Fe)	39.50 min	--
Carbon (C)	--	0.10
Aluminium (Al)	0.15	0.60
Titanium (Ti)	0.15	0.60
Al + Ti	0.30	1.20
Manganese (Mn)	--	1.50
Silicon (Si)	--	1.00
Copper (Cu)	--	0.75
Sulphur (S)	--	0.015

Mechanical Properties of Incoloy 800 Stud Bolts

These values apply to Alloy 800 Stud Bolts in the annealed condition. The high iron content keeps costs lower than pure nickel alloys while still delivering solid mechanical performance at elevated temperatures.

Property	Value
Tensile Strength	517 MPa min
0.2% Yield Strength	207 MPa min
Elongation	30% min
Reduction of Area	50% min
Hardness (HRB)	85 max
Modulus of Elasticity	196 GPa

Physical Properties of Incoloy 800 Stud Bolts

The physical constants below are used in thermal system design, flange load calculations, and selection for high-temperature cyclic service.

Property	Value
Density	7.94 g/cm³
Melting Range	1357 – 1385°C
Specific Heat	460 J/kg·°C
Thermal Conductivity	11.5 W/m·°C (at 21°C)
Electrical Resistivity	0.989 µΩ·m
Magnetic Permeability	1.014 (essentially non-magnetic)
Coefficient of Thermal Expansion	14.4 µm/m·°C (21–538°C)

Dimension Chart of Incoloy 800 Stud Bolts

The table below is consistent with dimensional data. All values apply to fully threaded and double-end stud bolts used with heavy hex nuts.

Nominal Diameter	Thread Pitch (UNC)	Body Diameter (mm)	Across Flats – Nut (mm)	Nut Height (mm)
1/4" (M6)	20 TPI	6.35	11.11	5.56
5/16" (M8)	18 TPI	7.94	14.29	6.75
3/8" (M10)	16 TPI	9.53	17.46	8.73
1/2" (M12)	13 TPI	12.70	22.23	11.18
5/8" (M16)	11 TPI	15.88	28.58	13.89
3/4" (M20)	10 TPI	19.05	34.93	16.67
7/8" (M22)	9 TPI	22.23	39.69	19.45
1" (M24)	8 TPI	25.40	44.45	22.23
1-1/4" (M30)	7 TPI	31.75	53.98	25.40
1-1/2" (M36)	6 TPI	38.10	65.09	31.75

Size Chart of Incoloy 800 Stud Bolts

The size chart below reflects standard lengths for UNS N08800 Stud Bolts. Non-standard lengths and custom thread forms are available on request.

Nominal Size (inches)	Length Range (mm)	Thread Length Each End (mm)	Full Thread Option
1/4"	25 – 150	16	Yes
3/8"	30 – 200	19	Yes
1/2"	40 – 300	22	Yes
5/8"	50 – 400	25	Yes
3/4"	60 – 500	28	Yes
7/8"	75 – 600	32	Yes
1"	100 – 750	38	Yes
1-1/4"	125 – 900	45	Yes
1-1/2"	150 – 1200	51	Yes
2"	200 – 1500	63	Yes

Torque Chart of Incoloy 800 Stud Bolts

Correct tightening torque is important for Alloy 800 Stud Bolts, particularly in high-temperature flanged joints where relaxation under heat can cause leakage. Values below are for dry (unlubricated) conditions at ambient temperature. Apply a 15–20% reduction when using anti-seize compound.

Bolt Size	Tensile Stress Area (mm²)	Recommended Torque – Dry (Nm)	Recommended Torque – Lubricated (Nm)
M10	58.0	55	47
M12	84.3	95	80
M16	157.0	230	195
M20	245.0	460	390
M24	353.0	790	670
M30	561.0	1,580	1,340
M36	817.0	2,700	2,295
1/2" UNC	126.7	120	100
5/8" UNC	198.1	245	208
3/4" UNC	284.9	430	365
1" UNC	506.7	950	807

Key Features of Incoloy 800 Stud Bolts

Below are 8 important features of Incoloy 800 Stud Bolts.

High-temperature oxidation resistance
Carburisation resistance
Creep strength
Corrosion resistance
Stress corrosion cracking resistance
Good weldability
Non-magnetic
Broad temperature capability

Applications of Incoloy 800 Stud Bolts

UNS N08800 Stud Bolts are chosen for applications where heat resistance and joint reliability over long service intervals matter most.

Petrochemical furnaces
Power generation
Chemical processing
Heat treatment equipment
Nuclear power
Offshore and marine
Food and pharmaceutical

How to Choose the Right Incoloy 800 Stud Bolts Supplier?

The wrong supplier can deliver material that meets the grade designation on paper but fails to perform in service. Below are the practical steps for vetting any supplier before placing an order for W.Nr. 1.4876 Stud Bolts.

Supplier Selection Criteria

Work only with suppliers who can provide full heat traceability back to the mill. The mill test report (MTR) should list the chemical composition, mechanical test results, and heat treatment condition for the specific heat number supplied with your order. Suppliers unable to furnish this documentation should not be used for critical service applications.

Technical Considerations

Confirm that the stud bolts are produced from bar stock per ASTM B408 / ASME SB408. Threading should conform to ASME B18.2.1 for inch series or DIN 976 for metric. For high-temperature service above 600°C, verify that the material is in the annealed condition and that the carbon content is within the controlled range for Incoloy 800 rather than the 800H or 800HT variants, unless the design specifically calls for those grades.

Quality & Certification Check

Request EN 10204 3.1 material certificates as a minimum. In Europe, pressure equipment has to be PED compliant. Third-party inspection by Bureau Veritas, SGS, TUV, or Lloyd’s Register adds confidence, especially for large or long lead orders. ISO 9001 certification of the manufacturing facility is a minimum requirement.

Procurement Tips for Bulk Orders

For bulk orders, negotiate a sample inspection and first article approval before you commit to full production. Use thread protector caps/moisture-resistant wrapping for packaging and label each piece linking to its heat number. Confirm lead times in writing and allow re-inspection if delivery is not within the agreed date.