ASTM A350 Specification

Forgings, Fasteners, Boltings, Stud Bolts, Screws, Nuts

Scope

ASTM A350 specification covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials, it does not cover raw material produced in these product forms.
No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.
Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified by the purchaser in the order.
ASTM A350 specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.

Related Specifications of ASTM A350

ASTM A350 Chemical Composition

Composition, wt. %
Grade Element
C, max Mn P, max S, max SiA Ni Cr Mo Cu Nb V N
ASTM A350 Grade LF1 0.30 0.60-1.35 0.035 0.040 0.15-0.30 0.40 maxB 0.30 maxB,C 0.12 maxB,C 0.40 maxB 0.02 maxD 0.08 max . . .
ASTM A350 Grade LF2 0.30 0.60-1.35 0.035 0.040 0.15-0.30 0.40 maxB 0.30 maxB,C 0.12 maxB,C 0.40 maxB 0.02 maxD 0.08 max . . .
ASTM A350 Grade LF3 0.20 0.90 max 0.035 0.040 0.20-0.35 3.3-3.7 0.30 maxC 0.12 maxC 0.40 max 0.02 max 0.03 max . . .
ASTM A350 Grade LF5 0.30 0.60-1.35 0.035 0.040 0.20-0.35 1.0-2.0 0.30 maxC 0.12 maxC 0.40 max 0.02 max 0.03 max . . .
ASTM A350 Grade LF6 0.22 1.15-1.50 0.025 0.025 0.15-0.30 0.40 maxB 0.30 maxB,C 0.12 maxB,C 0.40 maxB 0.02 max 0.04-0.11 0.01-0.030
ASTM A350 Grade LF9 0.20 0.40-1.06 0.035 0.040 ... 1.60-2.24 0.30 maxC 0.12 maxC 0.75-1.25 0.02 max 0.03 max . . .
ASTM A350 Grade LF787 0.07 0.40-0.70 0.025 0.025 0.40 max 0.70-1.00 0.60-0.90 0.15-0.25 1.00-1.30 0.02 min 0.03 max . . .
  • A When vacuum carbon-deoxidation is required by Supplementary Requirement S4, the silicon content shall be 0.12 % maximum.
    B The sum of copper, nickel, chromium, vanadium and molybdenum shall not exceed 1.00 % on heat analysis.
    C The sum of chromium and molybdenum shall not exceed 0.32 % on heat analysis.
    D By agreement, the limit for columbium may be increased up to 0.05 % on heat analysis and 0.06 % on product analysis.

ASTM A350 Mechanical Requirements

Properties Grades
ASTM A350 Grade LF1 and ASTM A350 Grade LF5 ASTM A350 Grade LF2 Classes 1 and 2 LF5 Class 2 ASTM A350 Grade LF3 ASTM A350 Grade LF6 ASTM A350 Grade LF9 ASTM A350 Grade LF787
Class 1 Classes 1 and 2 Class 1 Classes 2 and 3 Class 2 Class 3
Tensile strength, ksi [MPa] 60-85 [415-585] 70-95 [485-655] 70-95 [485-655] 66-91 [455-630] 75-100 [515-690] 63-88 [435-605] 65-85 [450-585] 75-95 [515-655]
Yield strength, min, ksi [MPa]B,C 30 [205] 36 [250] 37.5 [260] 52 [360] 60 [415] 46 [315] 55 [380] 65 [450]
Elongation: Standard round specimen, or small proportional specimen, min % in 4D gage length 25 22 22 22 20 25 20 20
Strip specimen for wall thickness 5⁄16 in. [7.94 mm] and over and for all small sizes tested in full section; min % in 2 in. [50 mm] 28 30 30 30 28 28 28 28
Equation for calculating min elongation for strip specimens thinner than 5⁄16 in. [7.94 mm]; min % in 2 in. [50 mm] t = actual thickness in inches 48t + 13 48t + 15 48t + 15 48t + 15 48t + 13 48t + 13 48t + 13 48t + 13
Reduction of area, min, % 38 30 35 40 40 38 45 45
  • A See 7.3 for hardness tests.
    B Determined by either the 0.2 % offset method or the 0.5 % extension under load method.
    C For round specimens only

ASTM A350 Certifications

  • EN 10204 3.1
  • EN 10204 3.2
  • PED 2014/68/EC
  • MERKBLATT AD 2000 W2/W7/W10
  • API 20 E BSL 1/ BSL 2
  • NACE MR 0175
  • NACE MR 0103

ASTM A350 Supplementary Requirements

S1 Other Impact Test Temperatures
S2 Stress-Relieved Test Specimens
S3 Lateral Expansion
S4 Vacuum Carbon-Deoxidized Steels
S5 Special Impact Test Requirements for Flanges
S6 Carbon Equivalent