ASTM A789/A789M

ASTM A789 A789M Covers Grades of nominal wall thickness, stainless steel tubing for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures.

This specification covers standard requirements for grades of nominal wall thickness, stainless steel tubing for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures. Heat and product analyses shall be performed wherein the steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, nitrogen, copper, and others. All tubes shall be furnished in the heat-treated condition in accordance with the specified temperature and quench conditions. When the final heat treatment is in a continuous furnace, or when heat treated condition is obtained directly by quenching after hot forming, the number of tubes of the same size and from the same heat in a lot shall be determined from the prescribed sizes of the tubes. The material shall conform to the prescribed tensile and hardness properties. Mechanical tests such as tension test, flaring test (for seamless tubes), flange test (for welded tubes), hardness test, and reverse flattening test shall be performed on the steel tubing. Each tube shall also be subjected to the nondestructive electric test or the hydrostatic test.

Scope

1.1 This specification2 covers grades of average wall thickness, or, if specified on the order, minimum wall thickness, of stainless steel tubing for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures.

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

1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Referenced Documents:

ASTM Referenced Standards.

A450 A450M Specification for General requirements for carbon, Ferritic Alloy, and Austenitic alloy steel tubes.

A480 A480M Specification for general requirements for flat-rolled stainless and heat-resisting steel plate, sheet, and strip.

A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys.

E527 Practice for numbering metals and alloys (UNS).

Chemical Composition

Heat Treatment Requirements

Tensile Requirements

Flange Test (for welded tubes)

One test shall be made on specimens from one end of one tube from each lot of finished tubes.

Flaring Test

One test shall be made on specimens from one end of one tube from each lot of finished tubes. The minimum expansion of the inside diameter shall be 10%.

Reverse Flattening Test

For welded tubes, one reverse flattening test shall be made on a specimen from each 1500Ft or 450m of finished tubing.

Hydrostatic or Nondestructive Testing

Each pipe shall be subjected to the nondestructive electric test or the hydrostatic test, the type of test to be used shall be at the option of the manufacturer, unless otherwise specified in the purchase order.

The hydrostatic test shall be in accordance with specification A 450/A 450M, except that in the calculation of the hydrostatic test pressure 64000(441.2) shall be substituted for 32000(220.6).

Markings

Marking prescribed in specification A450/A 450M, The marking shall indicate whether the tubing is seamless or welded.

Note:

• Mill test certificates will be issued according to EN10204.3.
• All tubes shall be supplied as per applicable ASTM A789 /A789M Specification.