ASTM A791 / ASME SA791 / Welded Unannealde Ferritic Stainless Steel Tubing supplier & distributor in India

ASTM A 791-88 / ASME SA 791

WELDED UNANNEALED FERRITIC STAINLESS STEEL TUBING1

This standard is issued under the fixed designation A 791; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ε) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This specification covers welded, unannealed, ferritic stainless steel tubing intended for high-temperature and corrosive serice where post-weld heat treatment is not necessary for corrosion resistance. These grades are com-monly known as the "straight-chromium" types and are characterized by being ferromagnetic. The high-chromium, ferritic alloys are sensitive to notch-brittleness on slow cooling to ordinary temperatures. These features should be recognized in the use of thest materials.The user requiring additional testing or examination is referred to the Supple-mentary Requirements or Ordering Information Section, or both. Users requiring a tubular product with post-weld heat treatment are referred to Specification A 2668 /A 268M.

1.2 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; theerfore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the "M" designation of this specification is specified in the order.

NOTE 1-For tubing smaller than 1/2 in. [12.7 mm] in outside diameter, the elongation values given for strip specimens in Table 1 shall apply. Mechanical property requirements do not apply to tubing smaller than 1/8 in. [3.2 mm]in outside diameter or with walls thinner than 0.015 in.[0.4mm].

Chemical composition

Grade	Mfg. Process	Chemical composition(%)
Grade	Mfg. Process	C	Si	Mn	P	S	Ni	Cr	Mo	Others
TP409	E, W	0.08Max	1.00Max	1.0Max	0.045Max	0.045Max	0.50Max	10.50~11.75	-	Ti 6C~0.75
TP439	E, W	0.07Max	1.00Max	1.00Max	0.040Max	0.030Max	0.50Max	17.00~19.00	N 0.04Max Al 0.15Max	Ti 0.20+ 4(C+N)~1.10
TPXM-27	E, W	0.01Max	0.40Max	0.40Max	0.02Max	0.02Max	0.50Max	25.0~27.0	0.75~1.50	Cu 0.2Max N 0.015Max
TPXM-33	E, W	0.06Max	0.75Max	0.75Max	0.040Max	0.020Max	0.50Max	25.0~27.0	Mo 0.75~1.50 Ti 7(C+N) 0.20Min 1.00Max	Cu 0.20Max N 0.040Max
25-4-4	E, W	0.025Max	0.75Max	0.75Max	0.040Max	0.030Max	3.5~4.5	24.5~26.0	3.5~4.2	N 0.035Max Ti+Cb 0.2+4(C+N)~0.080
26-3-3	E, W	0.030Max	1.00Max	1.00Max	0.040Max	0.030Max	1.0~3.50	25.0~28.0	3.0~3.50	N 0.040Max Ti+Cb=6(C+N) 0.20Min 1.00Max
29-4	E, W	0.010Max	0.20Max	0.30Max	0.025Max	0.15Max	28.0~30.0	3.5~4.2	-	Cu 0.15Max N 0.020Max
29-4-2	E, W	0.010Max	0.20Max	0.30Max	0.025Max	0.20Max	2.0~2.5	28.0~30.0	3.5~4.2	Cu 0.15Max N 0.020Max
18-2	E, W	0.030Max	1.00Max	1.00Max	0.040Max	1.00Max	1.00Max	28.0~30.0	3.60~4.20	N 0.045Max (Ti+Cb)=6(C+N) 0.20Min 1.00Max
29-4C	E, W	1.00Max	1.00Max	1.00Max	0.040Max	1.00Max	1.00Max	17.5~2.50	1.75~2.50	N 0.035Max (Ti+Cb)=6(C+N) 0.20Min 1.00Max

Mechanical Properties

Grade	Tensile Test MPa or N/mm2		Remaks (Similar to JIS)	Possibility Temperature
Grade	Min Yield point	Tensile Strength	Remaks (Similar to JIS)	Possibility Temperature
TP409	205	380	for High Temperature Service	-
TP439	205	415		-
TPXM-27	275	450		-
TPXM-33	310	415		-
25-4-4	515	620		-
26-3-3	450	585		-
29-4	415	550		-
29-4-2	415	550		-
18-2	240	415		-
29-4C	415	515		-

2. Referenced Documents

2.1 ASTM Standards : A 268/A 268M Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service2

A 450/A 450M Specification for General Requirements for Carbon, Ferritic Alloy, and Austenitic Alloy Steel Tubes2
A 700 Practices for Packaging, Marking, and Loading Methods for Steel Products for Domestic Shipment3
A 763 Practices for Detecting Susceptibility to Intergranular Attack in Ferritic Stainless Steels4

--------------------------------------

1This specification is under the jurisiction of ASTM Committee A-1 on Steel, Stainless Steel, and Prlated Alloys and is the direct responsibility of Subcommittee A01.10 on Pipe. Current edition approved July 15, 1991, Published September 1991.

Originally published as A790-81. Last previous edition A791/A 791M-90 2Annual Book of ASTM Standards, Vol 01.01. 3Annual Book of ASTM Standards, Vol 01.05. 4Annual Book of ASTM Standards, Vol 01.03.

TABLE 1 Tensile Requirements

Grade	UNS Designation	Tensile Strength, min, ksi [MPa]	Yield Strength, min, ksi [MPa]	ElongationA in 2 in. or 50mm min, %
TP 409	S40900	55[380]	30[205]	20
TP 439	S40335	60[415]	30[205]	20
TP XM-27	S44627	65[450]	40[275]	18
TP XM-33	S44626	68[410]	45[310]	20
25-4-4	S44635	90[620]	75[515]	12
26-3-3	S44660	85[585]	65[450]	20
29-4	S44700	80[550]	60[415]	20
29-4-2	S44800	80[550]	60[415]	20
18-2	S44400	60[415]	35[240]	20
29-4C	S44735	75[515]	60[415]	12

AFor longitudinal strip tests, a deduction of 0.60% for 29-4C, 0.90% for TPXM-27 and 1.00% for all other grades shall be made
from the basic minimum elongation for each 1/32 in. [0.8mm] decrease in wall thickness below 5/18 in.[8mm]. The following
table gives the computed minimum values :

Wall Thickness in.	mm	Elongation in 2 in. or 50mm, min, %
		29-4C	TP XM-27	All other Grades
5/16[0.312]	8	12	18	20
9/32[0.281]	7.2	11	17	19
1/4[0.250]	6.4	11	16	18
7/32[0.219]	5.6	10	15	17
3/16[0.188]	4.8	10	14	16
5/32[0.156]	4	9	13	15
1/8[0.125]	3.2	8	13	14
3/32[0.332]	2.4	8	12	13
1/16[0.062]	1.6	7	11	12
0.062 to 0.035, excl	1.6 to 0.9	7	10	12
0.035 to 0.222, excl	0.9 to 0.6	7	10	11
0.022 to 0.015, excl	0.6 to 0.4	6	10	11

NOTE - The above taaable gives the computed minimum elongation values for each 1/32 in.[0.8mm] decrease in
wall thickness. Where the wall thickness lies between two values shown above, the minimum elongation value
shall be determined by the following equation : B Grade 29-4C E = 19.2t +6.00 [E = 0.75t + 6.00]
Grade TP XM-27 E = 28.8t + 9.00 [E = 1.13t + 9.00]

All Other Grades E = 32t + 10.00 [E = 12.5t +10.00] where : E = elongation in 2 in. or 50mm, %, and
t = actual thickness of specimens, in.[mm].
BCalculated elongation requirements shall be rounded to the nearest whole number.

TABLE 2 Chemical Requirements

UNSS Grade	S40900 TP 409	S40335 TP 439	S44627 TP XM-327	S44626 TP XM-33	S44635 25-4-4	S44660 26-3-3	S44700 29-4	S44800 29-4-2	S44735 29-4C	S44500 18-2
Composition, %
Carbon, max	0.08	0.07	0.01C	0.06	0.025	0.030	0.010	0.010	0.030	0.025
Manganese,max	1.0	1.00	0.40	0.75	1.00	1.00	0.30	0.30	1.00	1.00
Phosphours,max	0.045	0.040	0.02	0.040	0.040	0.040	0.025	0.025	0.040	0.040
Sulfur,max	0.045	0.030	0.020.40	0.020	0.030	0.030	0.020	0.020	0.030	0.030
Siicon,max	1.00	1.00	0.5Dmax	0.75	0.75	1.00	0.20	0.20	1.00	1.00
Nickel	0.50max	0.50max	25.0-27.5	0.50max	3.5-4.5	1.0-3.50	2.0-2.5	2.0-2.5	1.00max	1.00max
Chromium	10.50-11.75	17.00-19.00	0.75-1.50	25.0-27.0	24.5-26.0	25.0-28.0	28.0-30.0	28.0-30.0	28.00-30.00	17.5-19.5
Molybdenum	...	...	...	0.75-1.00	3.5-4.5	3.0-4.0	3.5-4.2	3.5-4.2	3.60-4.20	1.75-2.50
Aluminum	...	0.15max	0.2max	...	...	...	...	...	...	...
Copper	...	...	0.015max	0.20max	...	...	0.15max	0.15max	...	...
Nitrogen	...	0.04max	...	0.040max	0.035max	0.040max	0.020maxB	0.020maxc	0.045max	0.035max
Titanium	6 x C min; 0.75 max	0.20+4(C+N) min; 1.10max		7X(C+N) but no less than 0.20min 1.00max	(Ti+Cb)= 0.20+4 (C+N) min;0.80 max	(Ti+Cb)= 6 X(C+N) but no less than 0.20min 1.00max			(Ti+Cb)= 6 X(C+N) but no less than 0.20min 1.00max	(Ti+Cb)= 0.20+4 (C+N) min;0.80 max
Columbium	...	...	0.05-0.20	...	...	...	...	...	...	...

ANew designation established in accordance with ASTM E 527 and SAE J1086, Practice for Numbering Metals and
Alloys (UNS). BCarbon plus nitrogen = 0.025max. CFor small diameter or thin walls, or both, tubing, where many
drawing passes are required, a carbon maximum of 0.015% is necessary. Small outside diameter tubes are defined
as those less than 0.500 in. [12.7mm] in outside diameter and light wall tubes as those less than 0.049 in.[1.2mm]
in everage wall thickness (0.040 in. [1mm]. DNickel plus copper.

TABLE 3 Hardness Requirements

Grade	Brinell Hardness, max	Rockwell Hardness, B Scale, max
TP 409	207	95
TP 439	207	95
TP XM-27	241	100
TP XM-33	241	100
25-4-4	...	30
26-3-3	265	25A
29-4	241	100
29-4-2	241	100
18-2	217	95
29-4C	...	25A

ARockwell hardness, C scale. NOTE 2 - For product analysis and flange requirements, the term lot applies to all tubes,
prior to cutting, of the same nominal size and wall thickness that are produced from the same heat of steel.
The number of tubes of the same size and from the same heat in a lot shall be determined from the size of the tubes as
prescribed in Table 4. NOTE 3 - For tensile and hardness test requirements, the term lot applies to all tubes,
prior to cutting, of the saaa8.1 The material shal conform to the tensile properties prescribed in Table 2.

TABLE4 Number of Tubes in a Lot

Size of Tube	Size of Lot
2 in.[50.8mm] and over in outside diameter and 0.200 in. [5.1mm] and over in wall thickness	not more than 50 tubes
Less than 2 in. [50.8mm] but over 1 in.[25.4mm] in outside diameter and under 0.200 in. [5.1mm] in wall thickness	not more than 75 tubes
1 in.[25.4mm] or less in outside diameters	not more than 125 tubes

10.2 The permissible variatioins in outside diameter given in Table 5 are not sufficient to provide for ovality in thin-walled tubes,
as defined in the Table. In such tubes, the maximum and minimum diameters at any cross section shall deviate from the
nominal diameter by no more than twice the permissible variation in outside diameter given in Table 5; however, the mean
diameter at that cross section must still be within the given permissible variation.

TABLE 5 Permissible Variations in Dimensions

Group	Size, Outside Dianmeter, in. [mm]	Permissible Variations in Outside Diameter, in.[mm]	Permissible Variations in Wall Thickness, %	Permissible Variations in Cut Lneght, in.[mm]A		Thin Walled TubesC
1	Up to 1/2[12.7], excl	±0.0055 [0.13]	±15	1/8 [3]	0	...
2	1/2 to 1 1/2[12.7 to 38.1], excl	±0.0005 [0.13]	±10	1/8 [3]	0	less than 0.065 in. [1.6mm] nominal
3	1 1/2 to 3 1/2[38.1 to 88.9], excl	±0.0010 [0.25]	±10	3/16 [5]	0	less than 0.095in. [2.4mm] nominal
4	3 1/2 to 5 1/2[88.9 to 139.7], excl	±0.0015 [0.38]	±10?	3/16 [5]	0	less than 0.150 in. [3.8mm] nominal
5	5 1/2 to 8[139.7 to 203.2], incl	±0.0030 [0.76]	±10	3/16 [5]	0	less than 0.150 in. [3.8mm] nominal

AThese tolerances apply to cut lengths up to and including 24 ft [7.3m]. For lengths over 24 ft [7.3m] andn additional over
tolerance of 1/8 in.[3mm] for each 10 ft [3.0m] or fraction thereof shall be permissible up to a maximum of 1/2 in.[3mm].

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