ASTM A105 Carbon Steel Flanges Manufacturer in India

What is ASTM A105 Carbon Steel?

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ASTM A105 (ASME SA105) is the premier standard specification for carbon steel forgings used in piping applications — flanges, fittings, valves, and pressure vessel nozzles — operating from ambient to elevated temperatures. The specification covers carbon-manganese steel forgings with a maximum carbon content of 0.35%, delivering a minimum UTS of 485 MPa (70 ksi) and yield strength of 250 MPa (36 ksi). The suffix "N" (A105N) indicates the normalised heat treatment condition, which refines grain structure, improves toughness, and ensures dimensional consistency — A105N is the industry-standard supply condition for flanges destined for oil and gas, petrochemical, and power generation service.

As the most widely used carbon steel flange material in the world, ASTM A105 flanges account for the vast majority of flanged piping connections in onshore oil fields, refineries, power plants, and general industrial pipework. They are specified under ASME B31.3 (Process Piping), ASME B31.4 (Pipeline Transportation), and ASME B31.8 (Gas Transmission) codes, and are rated for service between −29°C (−20°F) and 538°C (1000°F). Tesco Steel & Engineering manufactures ASTM A105 / ASME SA105 flanges in all types — WNRF, SORF, BLRF, SWRF, LJTF, THRF, RTJ — from NPS ½ to 60, Class 150 to 2500, with EN 10204 3.1 MTC on every shipment.

Important: Carbon steel (ASTM A105) has no inherent corrosion resistance. Unlike stainless steel or alloy steel, it requires external protection — paint, epoxy coating, hot-dip galvanising, or cathodic protection — for any service involving moisture, soil contact, or corrosive media. For corrosive fluid service, specify stainless steel (A182 F304/F316) or alloy steel grades.

Carbon Steel Flange Grade Selection Guide

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Three ASTM forged carbon and alloy steel standards cover the full temperature spectrum for piping flanges:

ASTM A105 Chemical Composition

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Element	ASTM A105 Limit (%)	Role in the Alloy
Carbon (C)	≤ 0.35	Primary strengthening element; limited to ensure weldability and ductility
Manganese (Mn)	0.60 – 1.05	Solid solution strengthener; improves hardenability and deoxidation
Silicon (Si)	0.10 – 0.35	Deoxidiser during steelmaking; minor solid solution strengthening
Phosphorus (P)	≤ 0.035	Controlled to prevent temper embrittlement and cold brittleness
Sulphur (S)	≤ 0.040	Limited to prevent hot cracking during welding and improve toughness
Copper (Cu)	≤ 0.40	Minor corrosion resistance improvement in atmospheric exposure
Nickel (Ni)	≤ 0.40	Toughness improvement; limited as it adds cost
Chromium (Cr)	≤ 0.30	Minor hardenability and oxidation resistance contribution
Molybdenum (Mo)	≤ 0.12	Minor creep resistance contribution at elevated temperatures
Vanadium (V)	≤ 0.08	Grain refinement; minor strengthening contribution
Cu + Ni + Cr + Mo + V	≤ 1.00 (sum)	Total alloying cap — ensures A105 remains a carbon steel, not alloy steel

Mechanical Properties — ASTM A105 vs Comparable Carbon & Alloy Steel Flange Grades

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Property	A105 / SA105 Carbon Steel	A350 LF2 Low-Temp CS	A182 F11 1.25Cr-0.5Mo	A182 F22 2.25Cr-1Mo
UTS (MPa min)	485	485	485	585
Yield Strength (MPa min)	250	250	275	380
Elongation (% min)	22	22	20	20
Reduction of Area (% min)	30	30	30	30
Max Hardness (HBW)	187	187	197	241
Min Service Temp (°C)	−29	−46	−29	−29
Max Service Temp (°C)	538	343	593	649
Impact Test Required?	No (default)	Yes, −46°C, 27 J	Optional	Optional
Density (g/cm³)	7.85	7.85	7.85	7.85
Forging Standard	ASTM A105	ASTM A350	ASTM A182	ASTM A182

ASTM A105 Pressure-Temperature Ratings (ASME B16.5 Group 1.1)

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ASME B16.5 Group 1.1 includes ASTM A105 and equivalent carbon steel forging grades. Allowable pressures (in bar) at key temperatures:

Temperature (°C)	Class 150 (bar)	Class 300 (bar)	Class 600 (bar)	Class 900 (bar)	Class 1500 (bar)	Class 2500 (bar)
−29 to 38	19.6	51.1	102.1	153.2	255.3	425.4
50	19.2	50.1	100.3	150.3	250.6	417.3
100	17.7	46.6	93.2	139.8	232.9	388.2
150	15.8	41.4	82.7	124.1	206.8	344.7
200	13.8	36.0	72.0	108.0	180.0	300.0
260	12.1	31.7	63.4	95.2	158.5	264.2
316	10.2	26.8	53.4	80.3	133.5	222.6
371	9.3	24.4	48.8	73.2	121.9	203.2
427	8.6	22.5	45.0	67.5	112.5	187.5
482	6.8	17.7	35.4	53.1	88.5	147.5
538	4.3	11.2	22.4	33.6	55.9	93.2

* Values from ASME B16.5-2017 Table 2-1.1 (Group 1.1). Note the sharp pressure drop above 427°C — for high-temperature sustained service, specify A182 F11 or F22 flanges instead.

ASTM A105 Flange Face Types Available

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Type	Abbreviation	Description & Application
Weld Neck Raised Face	WNRF	Long tapered hub welded to pipe butt-end. Superior stress distribution and fatigue resistance. First choice for high-pressure, elevated-temperature, or vibrating service — ASME B31.3 preferred type for process piping Class 900 and above.
Slip-On Raised Face	SORF	Slides over pipe and double-fillet welded. Easier to align during erection; 30–50% lower material cost than WNRF. Used extensively in Class 150–600 general plant and utility piping systems.
Blind Raised Face	BLRF	Solid disc to close a pipe end, vessel nozzle, or branch connection. Specified for line isolation, hydrostatic testing, and periodic access connections. The thickest, highest-stressed flange type per ASME B16.5.
Socket Weld Raised Face	SWRF	Pipe inserted into counterbore socket and fillet-welded. Standard for small-bore (NPS ½–2) Class 3000/6000 high-pressure instrument and utility lines.
Threaded / Screwed Raised Face	THRF / SCRF	Internal NPT or BSP threads engage directly onto threaded pipe. Used where welding is not permitted (explosive atmospheres) or for temporary connections. Not recommended for elevated temperature cyclic service.
Lap Joint (Van Stone)	LJTF	Used with a stub-end; flange rotates freely for bolt-hole alignment. Cost-effective for systems requiring frequent dismantling, such as heat exchanger nozzles and sampling connections.
Ring Type Joint	RTJ	Machined groove accepts an octagonal or oval metallic ring gasket. Mandatory for Class 900, 1500, and 2500 in high-pressure service such as wellheads, subsea manifolds, and high-pressure separator vessels.
Long Weld Neck	LWN	Extended weld neck acts as a nozzle neck. Used on vessel manways, pressure vessel nozzles, and equipment connections where a welding neck extension is needed.

ASTM A105 Grade Cross-Reference & Equivalents

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Standard / System	Designation / Equivalent
ASTM / ASME (Flanges & Forgings)	A105 / SA105 (normalised: A105N / SA105N)
ASME (Bolting)	A193 B7 studs / A194 2H heavy hex nuts (standard companion fasteners)
DIN / EN Material Number	1.0460 (C22.8) — close equivalent
EN Standard	EN 10222-2 P280GH (elevated temperature forgings)
BS Standard	BS 1503 Grade 223 (carbon steel pressure vessel forgings)
JIS	JIS G3201 SF490A (carbon steel forgings for general use)
IS (Indian Standard)	IS 2062 Grade B / IS 2002 Grade 2B
GOST (Russian)	GOST 8479-70 Grade III
Heat Treatment Condition	Normalised (N) — standard supply condition for flanges
Filler Metal (GTAW)	ER70S-6 (AWS A5.18)
Electrode (SMAW)	E7018 (AWS A5.1) — low-hydrogen
Electrode (FCAW)	E71T-1 (AWS A5.20)
Related Low-Temp Grade	ASTM A350 LF2 (impact tested to −46°C)
Related High-Temp Grade	ASTM A182 F11 (1.25Cr-0.5Mo) / F22 (2.25Cr-1Mo)

ASTM A105 Flange Specifications & Dimensions

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Standard Dimensional & Supply Parameters
Size Range	NPS ½" to 60" (DN 15 to DN 1500)
Pressure Classes (ASME B16.5)	Class 150, 300, 600, 900, 1500, 2500
Pressure Classes (ASME B16.47)	Class 75, 150, 300, 400, 600, 900 (Series A & B)
Bore Schedule	STD, XS, XXS, Schedule 10, 20, 40, 80, 120, 160
PN Ratings (EN / DIN)	PN 6, 10, 16, 25, 40, 64, 100, 160, 250, 320, 400
Face Types	RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint), MF (Male & Female), TG (Tongue & Groove)
Face Finish	125–250 μin Ra AARH (serrated), 63–125 μin (smooth), RTJ groove per B16.20
Material Standard	ASTM A105 / ASME SA105
Dimensional Standards	ASME B16.5, ASME B16.47, MSS SP-44, AWWA C207, API 6A

ASME B16.5 Class 150 Raised Face — Representative Dimensions (ASTM A105 WNRF)

NPS	OD (mm)	Bolt Circle (mm)	No. of Bolts	Bolt Size	Raised Face Dia. (mm)	Flange Thickness (mm)
½"	89	60	4	M12	35	9.6
¾"	98	69	4	M12	43	11.2
1"	108	79	4	M16	51	11.2
1½"	127	98	4	M16	73	12.7
2"	152	121	4	M16	92	14.2
3"	190	152	4	M20	127	15.9
4"	229	190	8	M20	157	17.5
6"	279	241	8	M24	216	20.6
8"	343	298	8	M24	270	22.4
10"	406	362	12	M27	324	23.9
12"	483	432	12	M27	381	25.4
16"	597	540	16	M30	489	28.6
20"	698	635	20	M30	597	31.8
24"	813	749	20	M30	711	34.9

* Dimensions per ASME B16.5-2017. For Class 300–2500, ASME B16.47 (NPS 26–60), or custom bores, contact us for certified dimensional drawings.

Welding ASTM A105 Carbon Steel Flanges — Requirements & Best Practice

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Parameter	Recommendation for ASTM A105
Filler — GTAW (TIG)	ER70S-6 (AWS A5.18) — recommended for its deoxidised chemistry on mill-scale surfaces
Electrode — SMAW (Stick)	E7018 (AWS A5.1) — low-hydrogen electrode; store and bake per AWS requirements to prevent hydrogen cracking
Wire — FCAW / GMAW	E71T-1C / E71T-1M (AWS A5.20); ER70S-6 for GMAW short-arc or spray transfer
Preheat Temperature	Min 93°C when t > 25 mm or CE > 0.43; min 10°C for t ≤ 25 mm to avoid hydrogen cracking on cold surfaces
Carbon Equivalent (CE)	CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15; typical A105: CE 0.38–0.47
Interpass Temperature	Max 300°C (to limit grain coarsening and impact property degradation in the HAZ)
Post-Weld Heat Treatment (PWHT)	Required per ASME B31.3 when nominal weld thickness > 19 mm (¾") in pressure-containing welds; temperature 620–680°C, hold time per code thickness tables
PWHT for Sour Service	Always perform PWHT at 620–680°C for sour (H₂S) service regardless of thickness, to reduce HAZ hardness to ≤ 248 HBW per NACE MR0175
Joint Preparation	Bevel per ASME B16.25 for butt welds; clean mill scale and rust from weld zone (25 mm each side) to bright metal before welding

Applications of ASTM A105 Carbon Steel Flanges

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International Standards for ASTM A105 Carbon Steel Flanges

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Category	Standard	Scope
Material (Forgings)	ASTM A105 / ASME SA105	Carbon steel forgings for piping — chemistry, mechanical properties, heat treatment
Flange Dimensions	ASME B16.5	Flanges NPS ½–24, Class 150–2500, RF/FF/RTJ
Large Flanges	ASME B16.47 Series A & B	Flanges NPS 26–60; Series A (MSS SP-44), Series B (API 605)
Pipeline Flanges	MSS SP-44	Steel pipeline flanges — large diameter (NPS 26–60)
Water Flanges	AWWA C207	Steel pipe flanges for water works service
Wellhead Flanges	API 6A / API 17D	Wellhead and Christmas tree flanges — A105 commonly used
Quality / MTC	EN 10204 Type 3.1	Material test certificates — chemistry, mechanical, heat treatment
NDE — MT	ASTM E709	Magnetic particle examination of carbon steel forgings
NDE — UT	ASTM A388 / ASME SA388	Ultrasonic examination of heavy forgings
Sour Service	NACE MR0175 / ISO 15156	Material requirements for H₂S-containing (sour) environments
Welding Filler	AWS A5.1 / A5.18 / A5.20	E7018 / ER70S-6 / E71T-1 filler metal specifications
European Standard	EN 1759-1 / EN 1092-1	Steel pipe flanges — European dimensional and material standards
JIS	JIS B2220	Japanese steel pipe flanges
Russian / CIS	GOST 33259	Pipeline flanges — Russian standard

ASTM A105 Flange Product Range — Tesco Steel & Engineering

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Tesco Steel & Engineering supplies the complete range of ASTM A105 / ASME SA105 carbon steel flanges: Weld Neck (WNRF / WNFF / WNRTJ), Slip-On (SORF / SOFF), Blind (BLRF / BLFF / BLRTJ), Socket Weld (SWRF / Class 3000 / 6000), Threaded / Screwed (THRF / Class 3000 / 6000), Lap Joint (LJTF), Long Weld Neck (LWN), Spectacle Blind, Plate Flanges, Orifice Flanges and custom nozzle flanges. Standard supply condition is A105N (normalised) with EN 10204 3.1 MTC. NACE MR0175-compliant material (hardness-verified) available on request.

Stock sizes available for immediate despatch: NPS ½ to 24 in Class 150, 300, and 600. Custom sizes NPS 26 to 60 in Class 150 to 2500 manufactured to order. Third-party inspection by SGS, Bureau Veritas, TÜV, Lloyd's, RINA, or TPIA accepted. Contact our team via Inquiry Form or call us for price list and lead times.

Frequently Asked Questions — ASTM A105 Carbon Steel Flanges

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What is ASTM A105 material for flanges?

ASTM A105 (ASME SA105) is the standard specification for carbon steel forgings for piping applications — flanges, fittings, and valve bodies for ambient and elevated temperature service. The material is a carbon-manganese steel with C ≤ 0.35%, Mn 0.60–1.05%, delivering minimum UTS 485 MPa and yield 250 MPa. The suffix "N" (A105N) denotes the normalised heat treatment condition — the standard supply condition for flanges.

What is the tensile strength of ASTM A105 carbon steel flanges?

Per ASTM A105 / ASME SA105: minimum UTS 485 MPa (70 ksi), minimum yield strength 250 MPa (36 ksi), minimum elongation 22% in 50 mm, and minimum reduction of area 30%. Maximum hardness is 187 HBW (96 HRB). Actual normalised material typically runs 500–580 MPa UTS in practice.

What is the maximum operating temperature for ASTM A105 flanges?

ASTM A105 flanges are rated to a maximum of 538°C (1000°F) per ASME B16.5 Group 1.1. However, the allowable pressure drops sharply above 427°C — Class 150 A105 at 427°C is only 8.6 bar vs 19.6 bar at ambient. For sustained service above 427°C, specify ASTM A182 F11 or F22 alloy steel flanges for better creep resistance.

What is the minimum operating temperature for ASTM A105 flanges?

ASTM A105 flanges are rated to a minimum service temperature of −29°C (−20°F) per ASME B16.5 without impact testing. Below −29°C, ASTM A350 LF2 (impact tested at −46°C, minimum 27 J Charpy) must be used instead.

What is the difference between ASTM A105 and ASTM A350 LF2 flanges?

Both grades share nearly identical chemistry and mechanical properties (UTS ≥ 485 MPa, YS ≥ 250 MPa). The critical difference: A350 LF2 mandates Charpy V-notch impact testing at −46°C with ≥ 27 J per specimen set, ensuring toughness in cold climates. A105 has no mandatory impact test and is only rated to −29°C. Use A350 LF2 for Arctic service, offshore cold-climate applications, and any system below −29°C.

What is the chemical composition of ASTM A105 carbon steel?

Per ASTM A105: C ≤ 0.35%; Mn 0.60–1.05%; Si 0.10–0.35%; P ≤ 0.035%; S ≤ 0.040%; Cu ≤ 0.40%; Ni ≤ 0.40%; Cr ≤ 0.30%; Mo ≤ 0.12%; V ≤ 0.08%. The sum of Cu + Ni + Cr + Mo + V must not exceed 1.00%. Carbon equivalent (CE) typically runs 0.38–0.47 for standard heat production material.

What filler metal is used for welding ASTM A105 carbon steel flanges?

Standard filler metals: ER70S-6 (AWS A5.18) for GTAW/TIG; E7018 (AWS A5.1) low-hydrogen electrode for SMAW; E71T-1 (AWS A5.20) for FCAW. Preheat to 93–150°C when t > 25 mm or CE > 0.43. PWHT at 620–680°C required per ASME B31.3 when weld thickness exceeds 19 mm in pressure-containing welds.

What hardness limit does ASTM A105 specify?

ASTM A105 specifies a maximum hardness of 187 HBW (96 HRB). For sour (H₂S) service per NACE MR0175 / ISO 15156, the effective limit is 250 HBW (22 HRC) for base metal and 248 HBW for HAZ and weld metal, to prevent sulphide stress cracking (SSC).

What dimensional standard applies to ASTM A105 flanges?

ASTM A105 flanges are dimensioned per: ASME B16.5 for NPS ½–24 in Classes 150–2500; ASME B16.47 Series A or B for NPS 26–60; MSS SP-44 for large-diameter pipeline flanges; and AWWA C207 for water works flanges. ASTM A105 only governs chemistry and mechanical properties — dimensional compliance is a separate purchase order requirement.

Can ASTM A105 flanges be used in sour (H₂S) service?

Yes, with restrictions. ASTM A105N flanges with hardness well below the 187 HBW ASTM limit are generally acceptable per NACE MR0175 / ISO 15156 provided: base metal hardness ≤ 250 HBW, HAZ and weld metal hardness ≤ 248 HBW after PWHT, and all weld repairs are PWHT-compliant. Always specify NACE compliance and hardness verification on the MTC for sour service orders.