What is ASTM A249 tube Heat Treatment Requirement？

ASTM A249 standard
ASTM A249 stainless steel tube is a standard specification for welded austenitic steel boiler, superheater, heat exchanger, and condenser tubes. It covers a range of sizes and thicknesses and is commonly used in high-temperature applications.

ASTM A249 tubing Heat Treatment

All material shall be furnished in the heat-treated condition in accordance with the requirements of Table.
One important aspect of producing ASTM A249 tubes is heat treatment. Heat treatment is a process of heating and cooling a material to alter its physical and mechanical properties. For tubes made of austenitic steel, the heat treatment process is critical to achieving the desired properties and performance characteristics. The heat treatment requirements for ASTM A249 ss welded tubes depend on the specific grade and type of steel used in the manufacturing process. Generally, the tubes are heat treated by either annealing, quenching and tempering, or stress relieving.

A solution annealing temperature above 1950°F [1065°C] may impair the resistance to intergranular corrosion after subsequent exposure to sensitizing conditions in TP309HCb, TP310HCb, TP321, TP321H, TP347, TP347H, TP348, and TP348H. When specified by the purchaser, a lower temperature stabilization or re-solution anneal shall be used subsequent to the initial high temperature solution anneal.

ASTM A249 Heat Treatment Requirements

Grade	UNS Number	Solutioning Temperature,min or range	Quenching Method
All grades not individually listed below		1900°F [1040°C]	A
...	S30815	1920°F [1050°C]	B
TP309HCb	S30941	1900°F [1040°C]C	B
TP310H	S3100g	1900F [1040°C]	B
TP310HCb	S31041	1900°F[1040°C]C	B
...	S31254	2100°F [1150℃]	B
TP316H	S31609	1900°F [1040°C]	B
TP321	S32100	1900°F [1040°C]C	B
TP321H	S32109	2000°F [1100°C]C	B
...	S32654	2100°F [1150℃]	B
...	S33228	2050°F [1120°C]	B
...	S34565	2050°F [1120℃]	B
...		2140°F [1170℃]	B
TP347	S34700	1900°F [1040°C]C	B
TP347H	S34709	2000F [1100°C]C	B
TP348	S34800	1900°F[1040°C]C	B
TP348H	S34809	2000°F [1100°C]C	B
...	S35045	2000°F [1100°C]	D
...	S38815	1950°F[1065°C]	B
...	N08367	2025°F [1110°C]	B
...	N08904	2000°F [1100°C]	B
...	N08926	2010°F[1105°C]	B

Notes:
A. Quenched in water or rapidly cooled by other methods, at a rate sufficient to prevent reprecipitation of carbides, as demonstrated by the capability of passing Practices A 262, Practice E. Note that Practices A 262 requires the test to be performed on sensitized specimens in the low carbon and stabilized types and on specimens representative of the as shipped condition of the other types. In the case of low-carbon types containing 3 % or more molybdenum, the applicability of the sensitizing treatment prior to testing shall be a matter for negotiation between the seller and purchaser.

B. Quenched in water or rapidly cooled by other methods.

C. A solution treating temperature above 1950°F [1065°C] may impair resistance to intergranular corrosion after subsequent exposure to sensitizing conditions in the indicated grades. When specified by the purchaser, a lower temperature stabilization or re-solution anneal shall be used subsequent to the higher-temperature solution anneal prescribed in this table.

D. Cooled in still air, or faster.