ASTM A106 Seamless Pipe

ASTM A106, identical with ASME SA-106, is the standard specification for carbon steel seamless pipe for high temperature service. It covers pipes sized from NPS 1/8 [DN 6] to NPS 48 [DN 1200] with nominal wall thickness as given in ASME B36.10M. Pipe having other dimensions can also be furnished under this standard provided such pipe complies with all other requirements of this specification. There are 3 grades available: Grade A, Grade B, and Grade C. The seamless pipe shall be suitable for bending, flanging, coiling and other similar forming operations, and for welding. Shijiazhuang Metalsin maintains a huge stock of ASTM A106 Gr.B seamless carbon steel pipes in 1/2″ to 36″ with wall thickness of SCH 40, SCH 80, XS, SCH 160, etc.

Material, Manufacture & Heat Treatment

The pipe shall be made from killed steel with the primary melting process being open-hearth, basic-oxygen, or electric furnace, possibly combined with separate degassing or refining. ASTM A106 seamless pipe shall be manufactured by the hot finished or cold drawn process. Hot finished pipe need not be heat treated. When required, it shall be heat treated at a temperature of 1200°F [650°C] or higher. Cold-drawn pipe shall be heat treated after the final cold draw pass at a temperature of 1200°F [650°C] or higher.

Chemical Requirements

ASTM A106	Grade A	Grade B	Grade C
C	≤ 0.25	≤ 0.30	≤ 0.35
Mn	0.27~0.93	0.29~1.06	0.29~1.06
P	≤ 0.035	≤ 0.035	≤ 0.035
S	≤ 0.035	≤ 0.035	≤ 0.035
Si	≥ 0.10	≥ 0.10	≥ 0.10
Cr	≤ 0.40	≤ 0.40	≤ 0.40
Cu	≤ 0.40	≤ 0.40	≤ 0.40
Mo	≤ 0.15	≤ 0.15	≤ 0.15
Ni	≤ 0.40	≤ 0.40	≤ 0.40
V	≤ 0.08	≤ 0.08	≤ 0.08

*All values are in weight percent. The sum of Cr, Cu, Mo, Ni, and V shall not exceed 1%.

Tensile Properties

ASTM A106	Grade A	Grade B	Grade C
T.S min. ksi [MPa]	48 [330]	60 [415]	70 [485]
Y.S min. ksi [MPa]	30 [205]	35 [240]	40 [275]

*T.S min.: tensile strength, minimum; Y.S min.: yield strength, minimum.

ASTM A106	Grade A		Grade B		Grade C
	L	T	L	T	L	T
EL-1, %	35	25	30	16.5	30	16.5
EL-2, %	28	20	22	12	20	12

*EL-1: basic minimum elongation transverse strip tests, and for all small sizes tested in full section. *EL-2: the minimum elongation when standard round 2″ [50 mm] gauge length test specimen is used. *L: longitudinal; *T: transverse.

Testing and Inspection

Chemical analysis, tensile test, bending test, flattening test, hydrostatic test, nondestructive electric test (NDE) which includes ultrasonic test and eddy current testing, dimensional inspection & visual examination.

Dimensions, Weights & Permissible Variations

The mass of any length of pipe shall not vary more than 10% over and 3.5% under that specified in ASME B36.10M. Generally, pipes ≤ 4″ may be weighed in convenient lot; pipe larger than 4″ shall be weighed separately. The tolerances (permissible variations) for outside diameter of ASTM A106 pipe are specified in below table. The minimum wall thickness at any point shall not be more than 12.5% under the specified wall thickness.

NPS	Tolerances in O.D
	Over	Under
	mm	mm
1/8 ≤ NPS ≤ 1-1/2	0.4	0.4
1-1/2 < NPS ≤ 4	0.8	0.8
4 < NPS ≤ 8	1.6	0.8
8 < NPS ≤ 18	2.4	0.8
18 < NPS ≤ 26	3.2	0.8
26 < NPS ≤ 34	4.0	0.8
34 < NPS ≤ 48	4.8	0.8

*For special OD or ID that is over 250 mm, the diameter tolerance is ±1% of the specified OD or ID.

Lengths and End Finishes

Similar to ASTM A53 pipe, seamless pipe conforming to ASTM A106 can be furnished in fixed length, single random length, or double random length. The fixed length are generally provided as 5.8 m, 11.8 m, 6 m or 12 m. Single random length generally indicates 4.8 m to 6.7 m in length while double random length usually refers to a minimum average length of 10.7 m and a minimum length of 6.7 m.

For sizes 1-1/2″ and smaller, all pipes shall be plain-end square cut. For sizes 2″ and larger, walls through extra strong weights shall be plain-end beveled. For sizes 2″ and larger, walls heavier than extra strong weights, shall be plain-end square cut. Plain-end beveled pipe has a bevel angle of 30°, 5° or 0° and a root face of 1.6 mm ± 0.8 mm shall be furnished.

ASME Code Applicability, Marking & Carbon Equivalent

ASTM A106 seamless pipe can be applied to a number of ASME Codes including ASME Boiler and Pressure Vessel Code Section I, Section III, Section VIII Division 1, Section XII. It is also applicable to almost all ASME pressure piping codes covered by ASME B31. A typical marking of the pipe can be shown as:  M  ASTM A106 Grade B  8″  SCH80  L=6m UT Heat No.85787. The carbon equivalent CE = %C + %Mn / 6 + ( %Cr + %Mo + %V ) / 5 + ( %Ni + %Cu ) / 15.