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ASME 1331.3-2016
<br /> Table 331.1.2 Alternate Postweld Heat Treatment (b) Any required PWHT shall be as required by the
<br /> Requirements for Carbon and Low Alloy Steels, qualified WPS.
<br /> P-Nos. 1 and 3 (c) For welds that require PWHT in accordance with
<br /> Minimum Holding Time at Table 331.1.1, the temperature of the material during
<br /> Decrease in Specified Minimum Decreased Temperature, PWHT shall be within the range specified. However,if
<br /> Temperature, °C( F) h [Note(1)] specified by the designer, the range may be extended
<br /> as permitted by Table 331.1.2,provided the lower critical
<br /> 55 (100)0) 4
<br /> 30 ( 2 temperature of the material is not exceeded.
<br /> 85 (150) [Note (2)] 10 331.2 Specific Requirements
<br /> 110 (200) [Note (2)] 20
<br /> Where warranted by experience or knowledge of ser-
<br /> NOTES: vice conditions, alternative methods of heat treatment
<br /> (1) Times shown apply to thicknesses 525 mm (1 in.).Add or exceptions to the basic heat treatment provisions of
<br /> 15 min/25 mm (15 min/in.) of thickness for control thick
<br /> nesses>25 mm (1 in.) (see para. 331.1.3). para.331.1 may be adopted as provided in paras.331.2.1
<br /> (2) A decrease>55°C (100°0 below the minimum specified and 331.2.2.
<br /> temperature is allowable only for P-No. 1, Group Nos. 1 and 2 331.2.1 Alternative Heat Treatment. Normalizing,
<br /> materials.
<br /> or normalizing and tempering, or annealing may be
<br /> applied in lieu of the required heat treatment after weld-
<br /> Fig. 328.5.4E This thickness shall be computed using ing,bending,or forming,provided that the mechanical
<br /> the following formulas: properties of any affected weld and base metal meet
<br /> (-a) for Fig. 328.5.41) use specification requirements after such treatment and that
<br /> the substitution is approved by the designer.
<br /> illustration(1) = Tb+ t,
<br /> 331.2.2 Exceptions to Basic Requirements. As indi-
<br /> illustration(2) = Th+t, cated in para.331,the basic practices therein may require
<br /> modification to suit service conditions in some cases.
<br /> illustration(3) = greater of Tb+ t,or T, + t, In such cases, the designer may specify more stringent
<br /> requirements in the engineering design,including heat
<br /> illustration(4) = Th+T + t treatment and hardness limitations for lesser thickness,
<br /> illustration(5) = Tb+ t, or may specify less stringent heat treatment and hard-
<br /> ness requirements,including none.
<br /> (-b) for Fig.328.5.4F use T,,,+t,for all illustrations When provisions less stringent than those in para.
<br /> (c) The term nominal material thickness as used in 331 are specified,the designer must demonstrate to the
<br /> Table 331.1.3 is the thicker of the materials being joined owner's satisfaction the adequacy of those provisions
<br /> at the weld. by comparable service experience, considering service
<br /> temperature and its effects, frequency and intensity of
<br /> 331.1.4 Heating and Cooling. The heating method thermal cycling, flexibility stress levels, probability of
<br /> shall provide the required metal temperature,metal tem- brittle failure, and other pertinent factors. In addition,
<br /> perature uniformity,and temperature control,and may appropriate tests shall be conducted, including WPS
<br /> include an enclosed furnace,local flame heating,electric qualification tests.
<br /> resistance, electric induction, or exothermic chemical
<br /> reaction. Above 315°C (600°F), the rate of heating and 331.2.3 Dissimilar Materials
<br /> cooling shall not exceed 335°C/h(600°F/hr)divided by (a) Heat treatment of welded joints between dissimi-
<br /> one-half the maximum material thickness in inches at lar ferritic metals or between ferritic metals using dis-
<br /> the weld,but in no case shall the rate exceed 335°C/h similar ferritic filler metal shall be at the higher of the
<br /> (600°F/hr). See Table 331.1.1 for cooling rate require- temperature ranges in Table 331.1.1 for the materials in
<br /> ments for P-Nos. 7, 10I, 11A, and 62 materials. the joint. This may require the use of material transition
<br /> joint designs.
<br /> 331.1.6 Temperature Verification. Heat treatment nt Heat treatment of welded joints including both
<br /> temperature shall be checked by thermocouple pyrome- ferritic and austenitic components and filler metals shall
<br /> ters or other suitable methods to ensure that the WPS requirements are met. See para. 328.7 for attachment of be as required for the ferritic material or materials unless
<br /> otherwise specified in the engineering design.
<br /> thermocouples by the low energy capacitor discharge
<br /> method of welding. 331.2.4 Delayed Heat Treatment. If a weldment is
<br /> (a) If used, the heat treatment furnace shall be cali- allowed to cool prior to heat treatment,the rate of cool-
<br /> brated such that the PWHT can be controlled within the ing shall be controlled or other means shall be used to
<br /> required temperature range. prevent detrimental effects in the piping.
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