Chemical Composition Element Specified / Typical Range (wt. %) C ≤0.08 Mn ≤2.00 Si ≤1.00 P ≤0.045 S ≤0.030 Cr 17.0–20.0 Ni 9.0–13.0 Mo — N ≤0.10 Nb+Ta ≥10×C; ≤1.00 Fe Balance Note: Values are presented as representative ASTM A182 grade requirements. The applicable standard edition and material certificate govern the final chemical limits.

Mechanical Properties Property Minimum / Requirement Tensile Strength, min. 515 MPa Yield Strength, 0.2%, min. 205 MPa Elongation, min. 30% Hardness As specified by applicable standard / product condition

Refinery and petrochemical piping High-temperature chemical processing Boiler and thermal equipment auxiliaries Heat exchangers and thermal cycling service Welded process systems requiring stabilization

Chemical Composition Element Specified / Typical Range (wt. %) C ≤0.08 Mn ≤2.00 Si ≤1.00 P ≤0.045 S ≤0.030 Cr 17.0–20.0 Ni 9.0–13.0 Mo — N ≤0.10 Nb+Ta ≥10×C; ≤1.00 Fe Balance Note: Values are presented as representative ASTM A182 grade requirements. The applicable standard edition and material certificate govern the final chemical limits.

Mechanical Properties Property Minimum / Requirement Tensile Strength, min. 515 MPa Yield Strength, 0.2%, min. 205 MPa Elongation, min. 30% Hardness As specified by applicable standard / product condition

Refinery and petrochemical piping High-temperature chemical processing Boiler and thermal equipment auxiliaries Heat exchangers and thermal cycling service Welded process systems requiring stabilization

347 Stainless Steel Flange

Grade: 347

Flange types：

Weld Neck (WN); Slip-On (SO); Blind (BL); Socket Weld (SW); Threaded (TH); Lap Joint (LJ); Orifice Flange where specified

Nominal size：

ASME: NPS 1/2–24 under B16.5; large diameter NPS 26–60 under B16.47; EN/JIS/GB/T sizes depend on applicable standard

Pressure rating：

ASME Class 150, 300, 400, 600, 900, 1500, 2500 (availability depends on size/type); EN/GB PN classes; JIS 5K–63K

347 is a niobium-stabilized austenitic stainless steel designed to provide improved resistance to intergranular corrosion after welding and during elevated-temperature exposure. Its composition is broadly similar to 304, with niobium added for stabilization. 347 flanges are commonly used in high-temperature piping, chemical processing, refinery equipment and applications where welded assemblies experience thermal cycling.

Chemical Composition

Element	Specified / Typical Range (wt. %)
C	≤0.08
Mn	≤2.00
Si	≤1.00
P	≤0.045
S	≤0.030
Cr	17.0–20.0
Ni	9.0–13.0
Mo	—
N	≤0.10
Nb+Ta	≥10×C; ≤1.00
Fe	Balance

Note: Values are presented as representative ASTM A182 grade requirements. The applicable standard edition and material certificate govern the final chemical limits.

Mechanical Properties

Property	Minimum / Requirement
Tensile Strength, min.	515 MPa
Yield Strength, 0.2%, min.	205 MPa
Elongation, min.	30%
Hardness	As specified by applicable standard / product condition

Refinery and petrochemical piping
High-temperature chemical processing
Boiler and thermal equipment auxiliaries
Heat exchangers and thermal cycling service
Welded process systems requiring stabilization

Introduction

Specification

Chemical Composition

Element	Specified / Typical Range (wt. %)
C	≤0.08
Mn	≤2.00
Si	≤1.00
P	≤0.045
S	≤0.030
Cr	17.0–20.0
Ni	9.0–13.0
Mo	—
N	≤0.10
Nb+Ta	≥10×C; ≤1.00
Fe	Balance

Note: Values are presented as representative ASTM A182 grade requirements. The applicable standard edition and material certificate govern the final chemical limits.

Mechanical

Mechanical Properties

Property	Minimum / Requirement
Tensile Strength, min.	515 MPa
Yield Strength, 0.2%, min.	205 MPa
Elongation, min.	30%
Hardness	As specified by applicable standard / product condition