Seamless and Welded Ferritic and Martensitic Stainless

Standard Specification for

Seamless and Welded Ferritic and Martensitic Stainless

Steel Tubing for General Service1

This standard is issued under the fixed designation A 268/A 268M; 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 (e) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

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 ferromagnetic. Two of these

grades, TP410 and UNS S 41500 (Table 1), are amenable to

hardening by heat treatment, and 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 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.

1.2 An optional supplementary requirement is provided, and

when desired, shall be so stated in the order.

1.3 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; 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.

2. Referenced Documents

2.1 ASTM Standards: 3

A 480/A 480M Specification for General Requirements for

Flat-Rolled Stainless and Heat-Resisting Steel Plate,

Sheet, and Strip

A 763 Practices for Detecting Susceptibility to Intergranular

Attack in Ferritic Stainless Steels

A 1016/A 1016M Specification for General Requirements

for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless

Steel Tubes

E 213 Practice for Ultrasonic Examination of Metal Pipe

and Tubing

E 273 Practice for Ultrasonic Examination of the Weld

Zone of Welded Pipe and Tubing

3. Terminology

3.1 Lot Definitions:

3.1.1 For flange and flaring 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. If final heat treatment is in a batch-type furnace, a lot

shall include only those tubes of the same size and from the

same heat that are heat treated in the same furnace charge. If

the final heat treatment is in a continuous furnace, 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 given in Table 2.

3.1.2 For tensile and hardness test requirements, the term lot

applies to all tubes, prior to cutting, of the same nominal

diameter and wall thickness that are produced from the same

heat of steel. If final heat treatment is in a batch-type furnace,

a lot shall include only those tubes of the same size and the

same heat that are heat treated in the same furnace charge. If

the final heat treatment is in a continuous

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