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ASTM A268 / ASME SA268 / Seamless and Welded Ferritic Stainless Steel Tubing supplier & distributor in India

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ASTM A268 

SEAMLESS AND WELDED FERRITIC STAINLESS STEEL TUBING 
FOR GENERAL SERVICE

This standard is issued under the fixed designation A 268; 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 specification² covers a number of grades of nominal-wall-thickness, stainless steel tubing for general corrosion-resisting and high-temperature service. Most of these grades are commonly known as the "straight-chromium" types and are characterized by being ferromag-netic. Two of these grades, TP410 and UNS S41500 (Table1), are amenable to hardening by heat treatment, and the high-chromium, ferritic alloys are sensitive to notch-brit-tleness on slow cooling to ordinary temperatures. These features should be recognized in the use of these materials.
Grade TP439 is used primarily for hot-water tank service and does not require post-weld heat treatment to prevent attack of the heat affected zone.

NOTE 1-TP329 (S32900) formerly in this specification. has been transferred to Specifications A 789/A 789M and 790/A 790M.

1.2 An optional supplementary requirement is provided,and when desire, shall be so stated in the order.

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

1.3 The values stated in either inch-pound units or SIunits 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; therefore, 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.

Grade   Remaks (Similar to JIS) Possibility Temperature
   
TP405 - - (SUS 405TB)
TP410 - - -
TP429 - - (SUS 430TB)
TP430 - - -
TP443 - - -
TP446-1 - - -
TP446-2 - - -
S40800 - - -
TP409 - - -
S41500 - - -
TP439 - - -
TP430Ti - - (SUS XM27TB)
TPXM-27 - - -
XM-33 - - -
18Cr-2Mo - - -
29-4 - - -
29-4-2 - - -
26-3-3 - - -
25-4-4 - - -
S44735 - - -




Chemical Requirements 


NOTE - TP329(S32900), formerly part of this specification, has been transferred to A 789/A 789M.

Grade TP 405 TP 410 TP 429 TP 430 TP 443 TP 446-1 TP 446-2A ... TP 409
UNS
DesignationB
S40500 S41000 S42900 S43000 S44300 S44600 S44600 S40800 S40900
Element Composition, %
C, max 0.18 0.15 0.12 0.12 0.20 0.20 0.12 0.08 0.08
Mn, max 1.00 1.00 1.00 1.00 1.00 1.50 1.50 1.00 1.00
P, max 0.040 0.040 0.040 0.040 0.040 0.040 0.040 0.045 0.045
S, max 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.045 0.045
Si, max 0.75 0.75 0.75 0.75 0.75 0.75 0.75 1.00 1.00
Ni 0.50max 0.50max 0.50max 0.50max 0.50max 0.50max 0.50max 0.80max 0.50max
Cr 11.5-13.5 11.5-13.5 14.0-16.0 16.0-18.0 18.0-23.0 23.0-30.0 23.0-30.0 11.5-13.0 10.50-11.75
Mo ... ... ... ... ... ... ... ... ...
Al 0.10-0.30 ... ... ... ... ... ... ... ...
Cu ... ... ... ... 0.90-0.25 ... ... ... ...
N ... ... ... ... ... 0.10-0.25 0.10-0.25 ... ...
Ti ... ... ... ... ... ... ... 12xC min;
1.10max
6xC min;
0.75max

Grade TP 439 ... TP 430 Ti TP 
XM-27
TP
XM-33D
18Cr-2Mo 29-4 26-4-2 26-3-3 25-4-4 ...C
UNS
Designation
S43035 S41500c S43036 S44627 S44626 S44400 S44700 S44800 S44660 S44635 S44735
Element Composition, %
C, max 0.07 0.05 0.10 0.01D 0.06 0.025 0.010 0.010 0.030 0.025 0.030
Mn, max 1.00 0.5-1.0 1.00 0.40 0.75 1.00 0.30 0.30 1.00 1.00 1.00
P, max 0.040 0.03 0.040 0.02 0.040 0.040 0.025 0.025 0.040 0.040 0.040
S, max 0.030 0.03 0.030 0.02 0.020 0.030 0.020 0.020 0.030 0.030 0.030
Si, max 1.00 0.60 1.00 0.40 0.75 1.00 0.20 0.20 1.00 0.75 1.00
Ni 0.050max 3.5-5.5 0.75max 0.5Fmax 0.50max 1.00max 0.15max 2.0-2.5 1.0-3.50 3.5-4.5 1.00max
Cr 17.00-19.00 11.5-14.0 16.00-19.50 25.0-27.5 25.0-27.0 17.5-19.5 28.0-30.0 28.0-30.0 25.0-28.0 24.5-26.0 28.00-30.00
Mo ... 0.5-1.0 ... 0.75-1.50 0.75-1.50 1.75-2.50 3.5-4.2 3.5-4.2 3.0-4.0 3.5-4.5 3.60-4.20
Al, max 0.15 ... ... ... ... ... ... ... ... ... ...
Cu, max ... ... ... 0.2 0.20 ... 0.15 0.15 ... ... ...
N, max 0.04 ... ... 0.015 0.040 0.035 0.020G 0.020G 0.040 0.035 0.045
Ti 0.20+4
(C+N)min;
1.10max
... 5xC min;
0.75max
... 7x(C+N)but
no less
than 0.20min;
100max
(TI+Cb)
0.20+4
(C+N)
min; 0.80
max
... ... (Ti+Cb)=
0.20-1.00
and 6x(C+N)
min
(Ti+Cb)=
0.20+4
(C+N)
min to
0.80max
(Ti+Cb)=
0.20-1.00
with 6(C+N)min
Cb ... ... ... 0.05-0.20 ... ... ... ... ... ... ...


ATPS446-2 is a lower carbon version of TP 446-1 that has a lower tensile strength but improved ductility and fracture toughness.

BNew designation established in accordance with Practice E 527 and SAE J10886. Practice for Numbering Metals and Alloys (UNS).

CW hen intergranular corrosion testing is specified, the test will be Practices A 763, using samples prepared as agrred upon between the seller and the purchaser.

DF or smal 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 average wall thickness (0.040 in.[1mm] in minimum wall thickness).

EPlate version of CA6NM.
FNickel plus copper.
GCarbon plus nitrogen = 0.025% max.

Number of Tubies in a Lot Heat Treated by the Continuous Process


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 or 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 diameter not more than 125 tubes

Tensile Requirements


NOTE - TP 329 (S32900), fomerly part of this specification has been transfered to A 789/A 789M and A 790/A 79M.

Grade and UNS Designation Tensile strength,
min,
ksi[MPa]
Yield strength,
min
ksi[MPa]
ElongationA
in 2 in or 50
mm, min,%
TP 405 
S40500
30[415] 30[205] 20
...
S40800
55[380] 30[205] 20
TP 410
S41000
60[415] 30[215] 20
TP 429, TP 430, and TP 430 Ti
S429000, S43000, and S43036
60[415] 35[240] 20
TP 443
S44300
70[485] 40[275] 20
TP 446-1
S44600
70[485] 40[275] 18
TP 446-2
S44600
65[450] 40[275] 20
TP 409
S40900
55[380] 30[205] 20
TP 439
S43035
60[415] 30[205] 20
...
S41500
115[795] 90[620] 15
TPXM-27
S44627
65[450] 40[275] 20
TPXM-33
S44626
68[470] 45[310] 20
18Cr-2Mo
S44400
60[415] 40[275] 20
29-4 and 29-4-2
S44700 and S44800
80[550] 60[415] 20
26-3-3
S44600
85[585] 65[450] 20
25-4-4
S44635
90[620] 75[515] 20
...
S44735
75[515] 60[415] 15


AFor longitudinal strip tests a deduction of 0.90% for TP 446-1 and S44735 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 5/16 in.[8mm]. 
The following table gives the computed minimum values.

TABLE 3 Continued


Wall Thickness Elongation in 2 in. or 50 mm, min,%
in. mm TP 446-1and S44735 S41500 All Other Grades
5/16[0.312] 8 18 15 20
9/32[0.281] 7.2 17 14 19
1/4[0.250] 6.4 16 14 18
7/32[0.219] 5.6 15 13 17
3/16[0.188] 4.8 14 12 16
5/32[0.156] 4 13 11 15
1/8[0.125] 3.2 13 11 14
3/32[0/094] 2.4 12 10 13
1/16[0/062] 1.6 11 9 12
0.062-0.035,excl 1.6-0.9 10 8 12
0.035-0.022, excl 0.9-0.6 10 8 11
0.022-0.015,incl 0.6-0.4 10 8 11



NOTE - The above table gives the computed minimum 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 :

Grade Equation
TP 446-1 and S44735 E = 28.8t + 9.00[E = 1.13t +9.00]
S41500 E = 24t + 7.5
All other grades E = 32t + 10.00 [E = 1.25f + 10.00]


where : 
E = elongation in 2in. or 50mm, %, and
t = actual thickness of specimen, in.[mm].
BCalculated elongation requirements shall be rounded to the nearest whole number.


Hardness Requirements 


NOTE - TP329 (S32900), formerly part of this specification, has been transferred to A 789/A 789M and A790/A 790M.

Grade UNS Designation Brinell Hardness,max Rockwell Hardness,
B Scale, max
TP 405 S40500 207 95
... S40800 207 95
TP 410 S41000 207 95
TP 429, TP 430, and
TP 430 Ti
S42900,S43000,
and S43036
190 90
TP 443 S44300 207 95
TP 446-1 and
TP 446-2
S44600 207 95
TP 409 S40900 207 95
TP 439 S43055 190 90
... S41500 295A 32
TP XM-33 and
TPXM-27
S44626 and
S44627
241 100
18CR-2Mo S44400 217 95
29-4 and 29-4-2 S44700 and
S44800
207 100
26-3-3 S44660 265 25A
25-4-4 S44635 270 27A
... S44735 ... 100

ARockwell hardness, C scale.

TABLE 5 Permissible Variations in Dimensions 

Group Size, Outside
Diameter, in.
[mm]
Permissible Variations 
in Outside Diameter, in.[mm]
Permissible
Variations in
Wall Thickness,C
%
Permissble Variations in Cut
Length, in.A[mm]
Thin Walled TubesB
Over Under
1 Up to 1/2[12.7],excl ±0.005[0.13] ±15 1/8 [3] 0 ...
2 1/2 to 1 1/2[12.7 to 38.1], excl ±0.005[0.13] ±10 1/8 [3] 0 less than 0.065[1.6mm]
nominal
3 1 1/2 to 3 1/2[38.1 to 88.9],excl ±0.010[0.25] ±10 3/16 [5] 0 less than 0.095[2.4mm]
nominal
4 3 1/2 to5 1/2[88.9 to 139.7],excl ±0.015[0.38] ±10 3/16 [5] 0 less than 0.150[3.8mm]
nominal
5 5 1/2 to 8[139.7 to 203.2],incl ±0.030[0.76] ±10 3/16 [5] 0 less than 0.150[3.8mm]
nominal

AThese tolerances apply to cut lengths up to and including 24 ft[7.3m].

For lengths over 24ft[7.3m] an additional over tolerance of 1/8 in.[3mm] for each 10 ft[3m] 
or fraction thereof shall be permissible up to a maximum of 1/2 in.[13mm].
BOvality provisions of 12.2 apply.
CW hen tubes as ordered require wall thicknesses 3/4 in.[19mm] or over,
or an inside diameter 60% or less of the outside diameter, 
a wider variation in wall thickness is required. 
On such sizes a variation in wall thickness of 12.5% over or under will be permitted. 
For tubes less than 1/2 in.[12.7mm] in inside diameter which cannot be successfully drawn over mandrel,
the wall thickness may vary ±15% from that specified.      




Material Comparison Tables (ASTM →KS, JIS, DIN, BS, NBN, NF, UNI)

ASTMSTANDARD UNS NO. KOREA/JAPANES GERMAN BRITISH BELGIAN FRENCH ITALIAN
KS/JIS Symbol KS/JIS Numbe Remarks DIN Type DIN Number Materiral Number Remarks B.S Number B.S Grade Remarks NBN Type NBN Grade Remarks AFNOR Type NF Number UNI Type UNI Number Ramarks
A 268 Seamless and welded Ferritic Stainless Steel Tubing for General Service                                    
Type 405 S40500     (3) X7 CrAl 17440 1.4002 (3b)     (3b)              
Type 410 S41000 STS 405 TB / SUS 405 TB D 3577 / G3463   X10 Cr13 17440 1.4006 (3b)     (3b)         (3)    

 

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