Pipe fittings of ASTM A420 WPL6 are widely utilized in pressure piping and pressure vessel service at low-temperatures. They can be furnished in accordance with a variety of ASME and MSS standards. According to ASME Boiler and Pressure Vessel Code, ASTM A420 WPL6 is not permitted for use in the construction of power boiler. However, it can be used for ASME Section III, Section VIII Division 1, and Section XII with maximum applicable temperature of 700°F, 850°F, and 650°F respectively. It pertains to material Group 1 designated with P-Number 1.

1. Chemical Composition of ASTM A420 WPL6

C	Mn	P	S	Si	Ni	Cr	Mo	Cu	Cb	V
≤0.30	0.50~1.05	≤0.035	≤0.040	0.15~0.40	≤0.40	≤0.30	≤0.12	≤0.40	≤0.02	≤0.08

*All values are in % unit.

2. Mechanical Properties of ASTM A420 WPL6

Tensile Strength, min.		Yield Strength, min.		Elongation (2 in.), min.
ksi	MPa	ksi	MPa	Longitudinal, %	Transverse, %
60~95	415~655	35	240	30	16.5

*All properties shall be measured at room temperature.

3. Charpy Impact Requirements

Size of Specimen	A*		B*
mm	ft·lbf	J	ft·lbf	J
10 by 10.0	13	17.6	10	13.6
10 by 7.5	10	13.6	8	10.8
10 by 5.0	7	9.5	5	7.0
10 by 2.5	4	5.4	3	4.1

*A – Charpy V-Notch Impact Value Required for Acceptance (Average of Three Specimens).
*B – Minimum Charpy V-Notch Impact Value Without Requiring Retest (One Specimen Only of a Set).
*The impact test temperature shall be -50°F[-45°C] for ASTM A420 Gr. WPL6.

4. Maximum Allowable Stress at Elevated Temperatures

Temp.	-20~100	150	200	300	400	500
*MAS	17.1	17.1	17.1	17.1	17.1	17.1
Temp.	600	650	700	750	800	850
*MAS	17.1	17.1	15.6	13.0	10.8	8.7

*Temp.: metal temperature, °F, not exceeding. *MAS: maximum allowable stress, ksi.

5. Design Stress Intensity at Elevated Temperatures

*Temp.	-20~100	150	200	300	400	500	600	650	700
*DSI	20.0	20.0	20.0	20.0	19.9	19.0	17.9	17.3	16.8

*Temp.: metal temperature, °F, not exceeding. *DSI: design stress intensity of A420 Gr. WPL6, ksi.

6. Tensile Strength at Elevated Temperatures

*Temp.	-20~100	200	300	400	500	600	650
*TS	60.0	60.0	60.0	60.0	60.0	60.0	60.0
*Temp.	700	750	800	850	900	950	1000
*TS	60.0	59.3	55.1	50.2	44.8	39.4	34.6

*Temp.: metal temperature, °F, not exceeding. *TS: tensile strength of ASTM A420 WPL6, ksi.

7. Yield Strength at Elevated Temperatures

*Temp.	-20~100	150	200	250	300	400	500	600
*YS	35.0	32.9	32.1	31.5	31.0	22.9	28.5	26.8
*Temp.	650	700	750	800	850	900	950	1000
*YS	25.9	25.1	24.2	23.5	22.8	22.1	21.5	20.8

*Temp.: metal temperature, °F, not exceeding. *YS: yield strength of ASTM A420 WPL6, ksi.