A105 Weld Neck Flange (ASME B16.5)

Forged carbon steel flange to ASTM A105 / ASME B16.5

A105 in the normalised condition is the standard forged carbon steel for flanges: 250 MPa minimum yield, 485 MPa minimum tensile, suitable for service from −29 °C to 425 °C. The weld neck design puts the weld away from the flange face and distributes stress along the hub, which is why it is the default for high-pressure and cyclic service. We supply DN15 to DN600 in classes 150 to 2500, plus larger sizes to ASME B16.47.

Equivalent grades

ASTM A105	A105 N
EN 1092-1	P250GH / 1.0460
JIS G3202	SF440A
GB/T 9124	A105

ASTM A105 · ASME B16.5

Chemical composition

C	Mn	Si	P	S	Cu	Ni	Cr	Mo
≤ 0.35	0.60 – 1.05	0.10 – 0.35	≤ 0.035	≤ 0.040	≤ 0.40	≤ 0.40	≤ 0.30	≤ 0.12

Values in % by mass. Limits are maxima unless a range is stated.

Mechanical properties

Grade	Rm (MPa)	Re (MPa)	A min (%)	Hardness
A105 N	≥ 485	≥ 250	≥ 22	≤ 187 HBW

Typical values per ASTM A105, ASME B16.5. The composition and mechanical properties of your order are stated on the EN 10204 3.1 mill test certificate.

Dimensions

Thickness / diameter (mm)	DN 15 – DN 600 (1/2″ – 24″)
Width / size class	Class 150 / 300 / 600 / 900 / 1500 / 2500
Length / face	Raised face RF, flat face FF, ring joint RTJ

Larger sizes to ASME B16.47. Forged, normalised, machined and marked · Sizes outside the ranges below are available on request — send the specification and quantity.

Typical applications

Pipeline and process piping
Oil, gas and petrochemical service
Steam and high-temperature lines
Pump and valve connections
Pressure vessel and heat exchanger nozzles

How to choose

Weld neck for high pressure, cyclic or high-temperature service; slip-on or plate flange where the line is low pressure and cost dominates. Below −29 °C, specify A350 LF2 rather than A105 — A105 loses impact toughness at low temperature.

Order & delivery

Lead time	15 – 30 days after deposit or L/C for mill-rolled material; stock sizes ship sooner.
Packing	Steel strapping, wooden pallets or crates, edge protection, custom shipping marks.
Payment	T/T with deposit, or L/C at sight. Terms are confirmed on the proforma invoice.
Minimum order	Normally one 20′ container per size; mixed sizes can be combined in one container.
Documents	Invoice, packing list, bill of lading, certificate of origin, EN 10204 3.1 mill test certificate.
Incoterms	FOB, CFR, CIF to your port. Third-party inspection (SGS, BV, Intertek) arranged on request.

FAQ

Do the flanges come with material certificates?

Yes: EN 10204 3.1 mill test certificate per heat, with the heat number stamped on the flange rim, plus dimensional inspection to ASME B16.5 and, on request, third-party witness.

Which materials can you supply in the same dimension?

A105, A350 LF2, A182 F304 / F316 / F316L / F321 and A694 F52 / F60, so a stainless or low-temperature line can be built from the same size range.

Full range, finishes and packing: Weld Neck Flange →