This specification2 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. This 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.
| Element | Grade LF1 | Grade LF2 | Grade LF3 | Grade LF5 | Grade LF6 | Grade LF9 | Grade LF787 |
|---|---|---|---|---|---|---|---|
| Carbon,max | 0.30 | 0.30 | 0.20 | 0.30 | 0.22 | 0.20 | 0.07 |
| Manganese | 0.60-1.35 | 0.60-1.35 | 0.90 max | 0.60-1.35 | 1.15-1.50 | 0.40-1.06 | 0.40-0.70 |
| Phosphorus, max | 0.035 | 0.035 | 0.035 | 0.035 | 0.025 | 0.035 | 0.025 |
| Sulfur, max | 0.040 | 0.040 | 0.040 | 0.040 | 0.025 | 0.040 | 0.025 |
| SiiconA | 0.15-0.30 | 0.15-0.30 | 0.20-0.35 | 0.20-0.35 | 0.15-0.30 | ... | 0.40 max |
| Nickel | 0.40 maxB | 0.40 maxB | 3.3-3.7 | 1.0-2.0 | 0.40 maxB | 1.60-2.24 | 0.70-1.00 |
| Chromium | 0.30 maxB,C | 0.30 maxB,C | 0.30 maxC | 0.30 maxC | 0.30 maxB,C | 0.30 maxC | 0.60-0.90 |
| Molybdenum | 0.12 maxB,C | 0.12 maxB,C | 0.12 maxC | 0.12 maxC | 0.12 maxB,C | 0.12 maxC | 0.15--0.25 |
| Copper | 0.40 maxB | 0.40 maxB | 0.40 max | 0.40 max | 0.40 maxB | 0.75-1.25 | 1.00-1.30 |
| Columbium | 0.02 maxD | 0.02 maxD | 0.02 max | 0.02 max | 0.02 max | 0.02 max | 0.02 min |
| Vanadium | 0.08 max | 0.08 max | 0.03 max | 0.03 max | 0.04-0.11 | 0.03 max | 0.03 max |
| Nitrogen | ... | ... | ... | ... | 0.01-0.000 | ... | ... |
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.
| Grades | ||||||||
|---|---|---|---|---|---|---|---|---|
| LF1 and LF5 Class 1 | LF2 Classes 1 and 2 | LF3 Classes 1 and 2 LF5 Class 2 | LF6 | LF9 | LF787 | |||
| 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 Elongation: | 30 [205] | 36 [250] | 37.5 [260] | 52 [360] | 60 [415] | 46 [315] | 55 [380] | 65 [450] |
| Standard round specimen, or small proportional specimen, min % in | 25 | 22 | 22 | 22 | 20 | 25 | 20 | 20 |
| 4D gage length 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 | 48 t + 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