This specification covers forged low alloy and stainless steel piping components for use in pressure systems. Included are flanges, fittings, valves, and similar parts to specified dimensions or to dimensional standards.

TABLE 1 Heat Treating Requirements
Grade	Heat Treat Type	Austenitizing/Solutioning		Cooling	Quenching Cool	Tempering Temperature,
		Temperature, Minimum		Media		Minimum or
			or Range, °F [°C]A		Below °F [°C]	Range, °F [°C]
			Low Alloy Steels
F 5, F 5a	anneal	1750	[955]	furnace cool	B	B
	normalize and temper	1750	[955]	air cool	B	1250 [675]
F 9	anneal	1750	[955]	furnace cool	B	B
	normalize and temper	1750	[955]	air cool	B	1250 [675]
F 91	normalize and temper	1900-1975 [1040-1080]		air cool	B	1350–1470 [730–800]
F 11, Class 1, 2, 3	anneal	1650	[900]	furnace cool	B	B
	normalize and temper	1650	[900]	air cool	B	1150 [620]
F 12, Class 1, 2	anneal	1650	[900]	furnace cool	B	B
	normalize and temper	1650	[900]	air cool	B	1150 [620]
F 22, Class 1, 3	anneal	1650	[900]	furnace cool	B	B
	normalize and temper	1650	[900]	air cool	B	1250 [675]
F 22V	normalize and temper or	1650	[900]	air cool or liquid	B	1250 [675]
	quench and temper

TABLE 2 Chemical RequirementsA

Identifi-

UNS

Grade

Composition, %

cation

Desig-

Carbon

Manga-

Phos-

Sulfur

Silicon

Nickel

Chromium

Molybde-

Colum-

Titan-

Other

Symbol

nation

nese

phorus

num

bium

ium

Elements

Low Alloy Steels

F 5C

K41545

4 to 6 % chromium

0.15

0.30–0.60 0.030

0.03

0.5

0.5

4.0–6.0

0.44–0.65

...

...

...

F 5aC

K42544

4 to 6 % chromium

0.25

0.6

0.04

0.03

0.5

0.5

4.0–6.0

0.44–0.65

...

...

...

F 9

K90941

9 % chromium

0.15

0.30–0.60 0.030

0.03

0.50–1.00

...

8.0–10.0

0.90–1.10

...

...

...

F 91

K90901

9 % chromium, 1 %

0.08–0.12

0.30–0.60 0.020

0.01

0.20–0.50

0.4

8.0–9.5

0.85–1.05

0.06–0.10  ...

N 0.03–0.07

molybdenum, 0.2 %

Al 0.02D

vanadium plus

V 0.18–0.25

columbium and

Ti 0.01D

Zr 0.01D

nitrogen

F 11

K11597

1.25 % chromium,

0.05–0.15

0.30–0.60 0.030

0.03

0.50–1.00

...

1.00–1.50

0.44–0.65

...

...

...

Class 1

0.5 % molybdenum

F 11

K11572

1.25 % chromium,

0.10–0.20

0.30–0.80 0.040

0.04

0.50–1.00

...

1.00–1.50

0.44–0.65

...

...

...

Class 2

0.5 % molybdenum

F 11

K11572

1.25 % chromium,

0.10–0.20

0.30–0.80 0.040

0.04

0.50–1.00

...

1.00–1.50

0.44–0.65

...

...

...

Class 3

0.5 % molybdenum

F 12

K11562

1 % chromium,

0.05–0.15

0.30–0.60 0.045

0.045

0.50 max

...

0.80–1.25

0.44–0.65

...

...

...

Class 1

0.5 % molybdenum

F 12

K11564

1 % chromium,

0.10–0.20

0.30–0.80 0.040

0.04

0.10–0.60

...

0.80–1.25

0.44–0.65

...

...

...

Class 2

0.5 % molybdenum

F 22

K21590 chromium-molybdenum

0.05–0.15

0.30–0.60 0.040

0.04

0.5

...

2.00–2.50

0.87–1.13

...

...

...

Class 1

...

F 22

K21590 chromium-molybdenum

0.05–0.15

0.30–0.60 0.040

0.04

0.5

...

2.00–2.50

0.87–1.13

...

...

...

Class 3

F 22V

K31835 2.25 % chromium, 1 %

0.11–0.15

0.30–0.60 0.015

0.01

0.1

0.25

2.00–2.50

0.90–1.10

0.07

0.03

Cu 0.20

molybdenum, 0.25 %

V 0.25–0.35

vanadium

B 0.002

Ca 0.015E

TABLE 3 Tensile and Hardness Requirements A
Grade Symbol	Tensile Strength, min, ksi [MPa]		Yield Strength, min, ksi [MPa]B	Elongation in 2 in. [50 mm] or 4D, min, %	Reduction of Area, min, %	Brinell Hardness Number, HBW
Low Alloy Steels
F 5	70	[485]	40 [275]	20	35	143–217
F 5a	90	[620]	65 [450]	22	50	187–248
F 9	85	[585]	55 [380]	20	40	179–217
F 91	90	[620]	60 [415]	20	40	190–248
F 11 Class 1	60	[415]	30 [205]	20	45	121–174
F 11 Class 2	70	[485]	40 [275]	20	30	143–207
F 11 Class 3	75	[515]	45 [310]	20	30	156–207
F 12 Class 1	60	[415]	32 [220]	20	45	121–174
F 12 Class 2	70	[485]	40 [275]	20	30	143–207
F 22 Class 1	60	[415]	30 [205]	20	35	170 max
F 22 Class 3	75	[515]	45 [310]	20	30	156–207
F 22V	85–110 [585–780]		60 [415]	18	45	174–237

A Where ellipses appear in this table, there is no requirement and the test for the value need neither be performed nor a value reported.
B Determined by the 0.2 % offset method. For ferritic steels only, the 0.5 % extension-under-load method may also be used.
C For sections over 5 in. [130 mm] in thickness, the minimum tensile strength shall be 70 ksi [485 MPa].
D For sections over 5 in. [130 mm] in thickness, the minimum tensile strength shall be 65 ksi [450 MPa].
E Longitudinal. The transverse elongation shall be 25 % in 2 in. or 50 mm, min.
F Longitudinal. The transverse reduction of area shall be 45 % min.
G For sections over 2 in. [50 mm] in thickness, the minimum tensile strength shall be 106 ksi [730 MPa]; the minimum yield strength shall be 75 ksi [515 MPa]