ASTM A182 F5 Flanges

ASTM A182 F5 flanges are forged flanges manufactured from a chromium-molybdenum low alloy steel know as 5Cr-0.5Mo with a UNS designation of K41545. They are widely utilized in pressure high-temperature services such as oil refineries, chemical and petrochemical industries, power plant piping, heat exchangers, and various pressure vessels.

Chemical composition of ASTM A182 Gr. F5

C	Mn	P	S	Si	Ni	Cr	Mo
0.15 max	0.30~0.60	0.030 max	0.030 max	0.50 max	0.50 max	4.0~6.0	0.44~0.65

The chromium (Cr) added in F5 not only increases resistance to abrasion and corrosion but also improves resistance to high-temperature hydrogen attack and graphitization. The molybdenum (Mo) content is acting as a grain refiner which enhances creep resistance and high-temperature strength. It also improves resistance to pitting corrosion in many environments. The creep strength of chromium-molybdenum low alloy is derived mainly from two sources: solid-solution strengthening of the matrix ferrite by  carbon, molybdenum and chromium as well as precipitation hardening by carbides. As a result, the creep strength (for 1% elongation in 10⁵ hours) of A182 Grade F5 may reach approx. 170 MPa at 450 °C.

Mechanical requirements and heat treatment.

Tensile Strength, min, ksi [MPa]	Yield Strength, min, kis [MPa]	Elongation, min, %	Reduction of Area, min, %	Brinell Hardness, HBW
70 [485]	40 [275]	20	35	143~217

According to ASME B16.5, pipe flanges manufactured from A812 Gr. F5 material shall be normalized and tempered at a temperature higher than 955 °C (1750 °F). The material is permissible but not recommended for prolonged use above 590 °C.

Pressure-Temperature ratings for ASTM A182 F5 flanges.

Temp. °C	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
-29~38	19.8	51.7	68.9	103.4	155.1	258.6	430.9
50	19.5	51.5	68.7	103.0	154.5	257.5	429.2
100	17.7	50.4	67.3	100.9	151.3	252.2	420.4
150	15.8	48.2	64.2	96.4	144.5	240.9	401.5
200	13.8	46.3	61.7	92.5	138.8	231.3	385.6
250	12.1	44.8	59.8	89.6	134.5	224.1	373.5
300	10.2	42.9	57.0	85.7	128.6	214.4	357.1
325	9.3	41.4	55.0	82.6	124.0	206.6	344.3
350	8.4	40.3	53.6	80.4	120.7	201.1	335.3
375	7.4	38.9	51.6	77.6	116.5	194.1	323.2
400	6.5	36.5	48.9	73.3	109.8	183.1	304.9
425	5.5	35.2	46.5	70.0	105.1	175.1	291.6
450	4.6	33.7	45.1	67.7	101.4	169.0	281.8
475	3.7	27.9	37.1	55.7	83.6	139.3	232.1
500	2.8	21.4	28.5	42.8	64.1	106.9	178.2
538	1.4	13.7	18.3	27.4	41.1	68.6	114.3
550	-	12.0	16.1	24.1	36.1	60.2	100.4
575	-	8.8	11.7	17.6	26.4	44.0	73.4
600	-	6.1	8.1	12.1	18.2	30.3	50.4
625	-	4.0	5.3	8.0	12.0	20.0	33.3
650	-	2.4	3.2	4.7	7.1	11.8	19.7