another clause in UG-8:
"The tubes, after finning, shall have a temper or condition that conforms to one of those provided in the
governing specifications, or, when specified, they may be furnished in the “as‐fabricated condition” where the finned portions of the tube are in the cold worked temper (as‐finned) resulting from the finning operation, and the unfinned portions in the temper of the tube prior to finning."
the same question about the word "temper".

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered at much higher temperatures.

Working metal introduces stresses in the material; different amounts dependent on the method of working. Hence the statements in the standard that talk about "cold worked" (as opposed to hot-rolled, or something else).

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I agree with Gr8blu.

Typically, when a temper/class/condition is required, it refers to a certain level of hardness. That level of hardness - and to a lesser extent, other material properties - is known to be as uniform as possible, based on the temperature and time of the tempering heat treatment.

The devil is in the details; she also wears prada.

hi, Gr8blu and DVWE,
Thanks for your reply.
i know what tempering heat treatment is referring to.
my question lies in its meaning in UG-8.
here is another sentence excerpted from general notes of SB-26 table-4 in SECTION II-B.
"Temper designations:
F As fabricated.
O Annealed.
T1 Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition.
T4 Solution heat-treated and naturally aged to a substantially stable condition.
T5 Cooled from an elevated temperature shaping process and then artificially aged.
T6 Solution heat-treated and then artificially aged.
T7 Solution heat-treated and stabilized."
from symbol F to T7， they stand for complete different condition of the material, but are all taken as a temper. does this temper referring to "tempering heat treatment"?
i doubt it.

hope for your further clarification.

Looking at your example of SB-26 material, go to Table 1B of II-D. You will see that the allowables vary with the different tempers.

Thus temper in the column heading in II-D is not a specific tempering method. It is merely the place where, if different tempers listed in a particular material specification will affect the allowable, then they will be noted here so you can select the appropriate row of the table.

hi, Geoff,
thanks for your reply.
i agree that temper here is not tempering heat treatment.
i guess it is generally equal to the word "condition", or something like that .
i just wonder why temper has such a practice.
thank you all.

They use 'Class/Condition/Temper' to cover all of the different options for different alloys.
The key is 'a temper of condition conforming to the governing specification'.
With some materials you are allowed to leave them as finned.
Some (stainless in some cases) require a full anneal after finning.
The condition has to match a listed one in the Code.

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P.E. Metallurgy, consulting work welcomed