ASTM A350 LF2 Flange

A350 LF2 flange is designed to be used in low temperature service down to -50°F (-46°C).

ASTM A350 LF2 Flange

A350 LF2 flanges are manufactured in accordance with ASTM A350 standard which specifies low-temperature carbon steel forgings for piping components such as flanges, fittings, valves and other similar parts. A350 LF2 flanges are commonly used in cryogenic applications where low temperature materials are required to ensure efficient and reliable operations.

ASTM A350 specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and valves for low-temperature service. The steel specimens shall be melt processed using open-hearth, basic oxygen, electric furnace or vacuum-induction melting. A sufficient discard shall be made to secure freedom from injurious piping and undue segregation. The materials shall be forged and shall undergo heat treatment such as normalizing, tempering, quenching and precipitation heat treatment. Heat analysis and product analysis shall be performed wherein the steel materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, columbium, vanadium, and nitrogen. The materials shall also undergo tension tests and shall conform to the required values of tensile strength, yield strength and elongation. Impact tests shall also be performed and the steel materials shall conform to the required values of minimum impact energy, temperature, and minimum equivalent absorbed energy. Hardness and hydrostatic tests shall also be performed.

ASTM A350 (ASME SA350) is the standard specification for carbon steel and low alloy steel forged flanges and flanged fittings for low temperature services.

Common use grade is ASTM A350 LF2 Class 1, corresponding material for piping in ASTM A333 Grade 6 and pipe fittings in ASTM A420 WPL6. With yield strength minimum 240 Mpa, and tensile strength in 480 Mpa to 655 Mpa, impact test temperature at -45℃.

Scope

ASTM A350 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.

Product furnished in ASTM A350/ ASME SA350 shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order. Failure to comply with A961/A961M will be considered nonconformance with A350. And in case of conflict between ASTM A350 and A961/A961M, this specification shall prevail.

ASTM A350 Chemical composition requirements

Element Composition, w.t % Grades
LF1 LF2 LF3 LF5 LF6 LF9 LF787
C ≤0.30 ≤0.30 ≤0.20 ≤0.30 ≤0.22 ≤0.20 ≤0.07
Mn 0.60-1.35 0.60-1.35 ≤0.90 0.60-1.35 1.15–1.50 0.40–1.06 0.40–0.70
P ≤0.035 ≤0.035 ≤0.035 ≤0.035 ≤0.025 ≤0.035 ≤0.025
S ≤0.040 ≤0.040 ≤0.040 ≤0.040 ≤0.025 ≤0.040 ≤0.025
Si 0.15-0.30 0.15-0.30 0.20-0.35 0.20-0.35 0.15-0.30 ... ≤0.40
Ni ≤0.40 ≤0.40 3.30-3.70 1.00-2.00 ≤0.40 1.60-2.24 0.70–1.00
Cr ≤0.30 ≤0.30 ≤0.30 ≤0.30 ≤0.30 ≤0.30 0.60–0.90
Mo ≤0.12 ≤0.12 ≤0.12 ≤0.12 ≤0.12 ≤0.12 0.15-0.25
Cu ≤0.40 ≤0.40 ≤0.40 ≤0.40 ≤0.40 0.75–1.25 1.00-1.30
Cb ≤0.02 ≤0.02 ≤0.02 ≤0.02 ≤0.02 ≤0.02 ≥0.02
V ≤0.08 ≤0.08 ≤0.03 ≤0.03 0.04-0.11 ≤0.03 ≤0.03
N ... ... ... ... 0.01–0.030 ... ...

*1. When vacuum carbon-deoxidation is required, the silicon content shall be 0.12% maximum.
*2. For grades LF1, LF2 & LF6, the sum of Cu, Ni, Cr, V and Mo shall not exceed 1.00 % on heat analysis.
*3. For all grades except grade LF787, the sum of Cr and Mo shall not exceed 0.32 % on heat analysis.
*4. For grades LF1 & LF2, the limit for Cb may be increased up to 0.05 % on heat analysis and 0.06 % on product analysis.
*5. The carbon equivalent C.E = [C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15] shall not exceed 0.45%.

ASTM A350 mechanical properties

Grade/Class Tensile Strength Yield Strength, min. Elongation, min. Hardness, max.
ksi MPa ksi MPa % HBW
LF1 CL1 60-85 415–585 30 205 25 197
LF5 CL1 60-85 415–585 30 205 25 197
LF2 CL1 70–95 485–655 36 250 22 197
LF2 CL2 70–95 485–655 36 250 22 197
LF3 CL1 70–95 485–655 37.5 260 22 197
LF3 CL2 70–95 485–655 37.5 260 22 197
LF5 CL2 70–95 485–655 37.5 260 22 197
LF6 CL1 66–91 455–630 52 360 22 197
LF6 CL2 75–100 515–690 60 415 20 197
LF6 CL3 75–100 515–690 60 415 20 197
LF9 63–88 435–605 46 315 25 197
LF787 CL2 65-85 450-585 55 380 20 197
LF787 CL3 75-95 515-655 65 450 20 197

*1. The elongation values are on the basis of standard round specimen, or small proportional specimen, min % in 4D gauge length.
*2. The yield strength shall be determined by either the 0.2 % offset method or the 0.5 % extension under load method.

Mechanical Properties

Tension Tests Requirements—The material shall conform to requirements for tensile properties in below table.

Heat Analysis and Product Analysis

A chemical heat analysis and product analysis in accordance with Specification A961/A961M shall be made and conform to the requirements as to chemical composition prescribed in this table. Leaded steels shall not be permitted. Product analysis

Heat Treatment & Welding Process

As specified by ASTM A350, after hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range. Forgings of grades other than Grade LF787 shall be furnished in the normalized, or normalized and tempered, or quenched and tempered condition. All quenched forgings shall be then tempered at 1100 °F [590 °C], minimum, holding at temperature a minimum of 30 min/in. [30 min/25 mm] of maximum thickness, but in no case less than 30 min. Grade LF787 forgings shall be furnished in either the normalized-and-precipitation heat treated condition or in the quenched-and-precipitation heat treated condition.

For Grade LF1 and LF2 forgings, the weld metal shall be deposited using carbon steel electrodes E 7015, E 7016, or E 7018, complying with AWS A 5.1. For Grade LF2 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 7015-A1; E 7016-A1, or E 7018-A1 complying with AWS 5.5; for Grade LF3 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 8016-C2 or E 8018-C2 complying with AWS A 5.5; for Grades LF5, LF9, and LF787 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 8016-C1 or E 8018-C1 complying withAWS A 5.5. For Grade LF6, the electrodes shall be low-hydrogen, E-XX15, E-XX16, or E-XX18 complying with AWS A 5.1 or A 5.5, as applicable.

The dimensional standards for ASTM A350 forgings

ASME B16.5 Steel Pipe Flanges and Flanged Fittings
ASME B16.9 Factory-MadeWroughtSteelButt-WeldingFittings
ASME B16.11 Forged Steel Fittings, Socket-Welding and Threaded4
ASME B16.34 Valves-Flanged, Threaded, and Welding End
ASME B16.47 Large Diameter Steel Flanges
API 600 Steel Gate Valves with Flanged or Butt-Welding Ends
API 602 Compact Design Carbon Steel Gate Valves for Refinery Use
API 605 Large Diameter Carbon Steel Flanges

Referenced Documents

ASTM Standards:

ASME Standards:

AWS Standards:

API Standards:

Manufacture – Melting and Forging

Melting Process – The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric-furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining, and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).

Discard – A sufficient discard shall be made to secure freedom from injurious piping and undue segregation.

Forging Process

Material for forgings shall consist of ingots, or forged, rolled, or strand cast blooms, billets, slabs, or bars.

Heat Treatment

After hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range.

Forgings grades except Grade LF787, should be heat treated in normalized, or normalized and tempered, or quenched and tempered. By manufacturer’s option, material that performed in quenched and tempered could be normalized prior to the austenitize/quenched operation.

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.

Hydro-static Test

Forgings manufactured under ASTM A350/ ASME SA350 shall be performed with a hydro-static test compatible with the rating of the finished item. Such tests shall be conducted by the manufacturer only when Supplementary Requirement S57 of Specification A961/A961M is specified.

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.

Ni-Hard Wearback Pipes Ni-Hard Wearback Pipes