ASTM A376 Seamless Austenitic Steel Pipe for High Temperature Central Station Service

1. Scope * 

1.1 This specification2 covers seamless austenitic steel pipe intended for high-temperature central-station service. Among the grades covered are five H grades and two nitrogen grades 
(304N and 316N) that are specifically intended for high temperature service. 
1.2 Optional supplementary requirements (S1 through S10) are provided. These supplementary requirements specify additional tests that will be made only when stated in the order, 
together with the number of such tests required. 
1.3 Grades TP321 and TP321H have lower strength requirements for nominal wall thicknesses greater than 3⁄8 in. [9.5mm]. 
1.4 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. 
NOTE 1—The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.” 
 

2. Referenced Documents 
2.1 ASTM Standards:
A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels3 
A 941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys4 
A 999/A 999M Specification for General Requirements for Alloy and Stainless Steel Pipe4 
E 112 Test Methods for Determining Average Grain Size5 
E 213 Practice for Ultrasonic Examination of Metal Pipe and Tubing6 
E 381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings5 
E 426 Practice for Electromagnetic (Eddy-Current) Examination of Seamless and Welded Tubular Products, Austenitic Stainless Steel, and Similar Alloys6 
2.2 ASME Boiler and Pressure Vessel Code:Section IX Welding Qualifications7
2.3 Other Standards:
SNT-TC-1A Personnel Qualification and Certification in Nondestructive Testing8 
 

3. Terminology 
3.1 Definitions—For definitions of terms used in this specification, refer to Terminology A 941. 
 

4. Ordering Information 
4.1 Orders for material to this specification should include the following, as required to describe the desired material adequately: 
4.1.1 Quantity (feet, centimetres, or number of lengths), 
4.1.2 Name of material (seamless austenitic steel pipe), 
4.1.3 Grade (Table 1), 
4.1.4 Size (nominal size, or outside diameter and schedule number or average wall thickness), 
4.1.5 Lengths (specific or random), (Permissible Variations in Length Section of Specification A 999/A 999M), 
4.1.6 End finish (Ends Section of Specification A 999/A 999M), 
4.1.7 Optional requirements (Section 9) (see Hydrostatic Test Requirements Section and the Permissible Variation in Weight for Seamless Pipe Section for weighing individual lengths, of Specification A 999/A 999M), (see 10.6, repairing by welding; 14.3, die stamping),

TABLE 1 Chemical Requirements

A The method of analysis for nitrogen shall be a matter of agreement between the purchaser and manufacturer. 
B The titanium content shall be not less than five times the carbon content and not more than 0.70 %. 
C The titanium content shall be not less than four times the carbon content and not more than 0.70 %. 
D The columbium content shall be not less than ten times the carbon content and not more than 1.10 %. 
E The columbium content shall be not less than eight times the carbon content and not more than 1.10 %. 
F This grade is intended for special purpose applications.

Tensile and Hardness Requirements

A For grade TP304, NPS8 or larger, and in schedules 140 and heavier, the required minimum tensile strength shall be 70 ksi [480 MPa]. 
B Prior to the issuance of A 376/A 376M – 88, the tensile and yield strength values were 75 [520] and 30 [210] respectively, for nominal wall greater than 3⁄8 in. 
[9.5 mm]. 
Editorially corrected.

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