Sheet1P No.Group No.ASME Section VIII-Division 1, Pressure VesselsASME Section I, Power BoilersASME B31.1, Power PipingASME B31.3, Process PipingPWHTPreheatPWHTPreheatPWHTPreheatPWHTPreheat11ASME Section VIII-Division 1; Requirements for PWHT of Table UCS-56 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal): Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating and Cooling rate: Max. Demo F (Demo C) per hr divided by the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C)/hr; Min. Demo F (Demo C)/hrFor Mandatory & Non-Mandatory thickness conditions of PWHT, See Note (2) of Table UCS-56For PWHT at lower temperatures for longer periods of time, See Note (1) of Table UCS-56ASME Section VIII-Division 1; Preheating from Appendix R (a) Demo F (Demo C) for material which has both a specified maximum carbon contentin excess of 0.30% and a thickness at the joint in excess of 1 in. (25 mm); (b) Demo F (Demo C) for all other materials of P-No. 1 group.ASME Section I; Mandatory Requirements for PWHT of Table PW-39 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal): Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating rate: The weldment shall be heated slowly to the holding temperature, Min. Demo F (Demo C)/hrCooling rate: Cool slowly in a still atmosphere to a temperature not exceeding Demo F (Demo C) For Non-Mandatory conditions of PWHT, See Notes (1), (3) of Table PW-39For PWHT at lower temperatures for longer periods of time, See Note (2) of Table PW-39ASME Section I; Preheating from Appendix A (A-100) (a) Demo F (Demo C) for material which has both a specified maximum carbon contentin excess of 0.30% and a thickness at the joint in excess of 1 in. (25 mm); (b) Demo F (Demo C) for all other materials of P-No. 1 group.ASME B31.1; Requirements for PWHT of Table 132 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended value, See Clause 132.2Heating and Cooling Rate: Demo F (Demo C) per hr divided by 1/2 the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C) per hrHolding Time Based on Nominal Thickness: Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)For Non-Mandatory conditions of PWHT, See Note (A) of Table 132For PWHT at lower temperatures for longer periods of time, See Note (B) of Table 132ASME B31.1; Preheating from Clause 131.4 Demo F (Demo C) for material which has both a specified maximum carbon content in excess of 0.30% and a thickness at the joint in excess of 1 in. (25 mm) for materials of P-No. 1 group.ASME B31.3; Requirements for PWHT of Table 331.1.1 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended valueHolding Time Based on Nominal Thickness: Over 3/4 in. (20 mm); 1 hr/in (2.4 min/mm), 1hr Min. PWHT is not required for thickness up to 3/4 in. (20 mm) for P-No. 1 group.ASME B31.3; Preheating from Table 330.1.1 Preheating is not required for P-No. 1 group.Recommended preheat based on Nominal Wall Thickness: Including and above 1 in. (25 mm): Demo F (Demo C)When Specified Min. Tensile Strength is above 71 ksi (490 MPa): Demo F (Demo C)31ASME Section VIII-Division 1; Requirements for PWHT of Table UCS-56 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating and Cooling rate: Max. Demo F (Demo C) per hr divided by the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C)/hr; Min. Demo F (Demo C)/hrFor Mandatory & Non-Mandatory thickness conditions of PWHT, See Notes (2), (3), (4) of Table UCS-56For PWHT at lower temperatures for longer periods of time, See Note (1) of Table UCS-56ASME Section VIII-Division 1; Preheating from Appendix R (a) Demo F (Demo C) for material which has either a specified minimum tensile strength in excess of 70,000 psi (480 MPa) or a thickness at the joint in excess of 5/8 in. (16 mm); (b) Demo F (Demo C) for all other materials of P-No. 3 group.ASME Section I; Mandatory Requirements for PWHT of Table PW-39 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating rate: The weldment shall be heated slowly to the holding temperature, Min. Demo F (Demo C)/hrCooling rate: Cool slowly in a still atmosphere to a temperature not exceeding Demo F (Demo C) For Non-Mandatory conditions of PWHT, See Notes (1), (3) of Table PW-39For PWHT at lower temperatures for longer periods of time, See Note (2) of Table PW-39ASME Section I; Preheating from Appendix A (A-100) (a) Demo F (Demo C) for material which has either a specified minimum tensile strength in excess of 70,000 psi (Demo MPa) or a thickness at the joint in excess of 5/8 in. (16 mm); (b) Demo F (Demo C) for all other materials of P-No. 3 group.ASME B31.1; Requirements for PWHT of Table 132 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended value, See Clause 132.2Heating and Cooling Rate: Demo F (Demo C) per hr divided by 1/2 the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C) per hrHolding Time Based on Nominal Thickness: Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)For Non-Mandatory conditions of PWHT, See Note (A) of Table 132For PWHT at lower temperatures for longer periods of time, See Note (B) of Table 132ASME B31.1; Preheating from Clause 131.4Demo F (Demo C) for material which has either a specified minimum tensile strengthin excess of 60,000 psi (410 MPa) or a thickness at the joint in excess of 1/2 in. (13 mm) for materials of P-No. 3 group.ASME B31.3; Requirements for PWHT of Table 331.1.1 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended valueHolding Time Based on Nominal Thickness: Over 3/4 in. (20 mm); 1 hr/in (2.4 min/mm), 1hr Min.Up to 3/4 in. (20 mm), if Min. T. S. is greater than 71 ksi (490 MPa):1 hr/in (2.4 min/mm), 1hr Min.PWHT for thickness up to 3/4 in. (20 mm) is not required, when Min. Tensile Strength is up to 71 ksi (490 MPa) for P-No. 3 group.ASME B31.3; Preheating from Table 330.1.1 Preheating is not required for P-No. 3 group.Recommended preheat based on Nominal Wall Thickness: Including and above 1/2 in. (13 mm): Demo F (Demo C)When Specified Min. Tensile Strength is above 71 ksi (490 MPa): Demo F (Demo C)32ASME Section VIII-Division 1; Requirements for PWHT of Table UCS-56 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating and Cooling rate: Max. Demo F (Demo C) per hr divided by the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C)/hr; Min. Demo F (Demo C)/hrFor Mandatory & Non-Mandatory thickness conditions of PWHT, See Notes (2), (3), (4) of Table UCS-56For PWHT at lower temperatures for longer periods of time, See Note (1) of Table UCS-56ASME Section VIII-Division 1; Preheating from Appendix R (a) Demo F (Demo C) for material which has either a specified minimum tensile strength in excess of 70,000 psi (480 MPa) or a thickness at the joint in excess of 5/8 in. (16 mm); (b) Demo F (Demo C) for all other materials of P-No. 3 group.ASME Section I; Mandatory Requirements for PWHT of Table PW-39 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)Heating rate: The weldment shall be heated slowly to the holding temperature, Min. Demo F (Demo C)/hrCooling rate: Cool slowly in a still atmosphere to a temperature not exceeding Demo F (Demo C) For Non-Mandatory conditions of PWHT, See Notes (1), (3) of Table PW-39For PWHT at lower temperatures for longer periods of time, See Note (2) of Table PW-39ASME Section I; Preheating from Appendix A (A-100) (a) Demo F (Demo C) for material which has either a specified minimum tensile strength in excess of 70,000 psi (Demo MPa) or a thickness at the joint in excess of 5/8 in. (16 mm); (b) Demo F (Demo C) for all other materials of P-No. 3 group.ASME B31.1; Requirements for PWHT of Table 132 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended value, See Clause 132.2Heating and Cooling Rate: Demo F (Demo C) per hr divided by 1/2 the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C) per hrHolding Time Based on Nominal Thickness: Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)For Non-Mandatory conditions of PWHT, See Note (A) of Table 132For PWHT at lower temperatures for longer periods of time, See Note (B) of Table 132ASME B31.1; Preheating from Clause 131.4Demo F (Demo C) for material which has either a specified minimum tensile strengthin excess of 60,000 psi (410 MPa) or a thickness at the joint in excess of 1/2 in. (13 mm) for materials of P-No. 3 group.ASME B31.3; Requirements for PWHT of Table 331.1.1 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended valueHolding Time Based on Nominal Thickness: Over 3/4 in. (20 mm); 1 hr/in (2.4 min/mm), 1hr Min.Up to 3/4 in. (20 mm), if Min. T. S. is greater than 71 ksi (490 MPa):1 hr/in (2.4 min/mm), 1hr Min.PWHT for thickness up to 3/4 in. (20 mm) is not required, when Min. Tensile Strength is up to 71 ksi (490 MPa) for P-No. 3 group.ASME B31.3; Preheating from Table 330.1.1 Preheating is not required for P-No. 3 group.Recommended preheat based on Nominal Wall Thickness: Including and above 1/2 in. (13 mm): Demo F (Demo C)When Specified Min. Tensile Strength is above 71 ksi (490 MPa): Demo F (Demo C)41ASME Section VIII-Division 1; Requirements for PWHT of Table UCS-56 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm) to 5 in. (125 mm); 1 hr/in. (2 min/mm)Over 5 in. (125 mm); 5 hr plus 15 min for each additional inch over 5 in. (125 mm)Heating and Cooling rate: Max. Demo F (Demo C) per hr divided by the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C)/hr; Min. Demo F (Demo C)/hrFor Mandatory & Non-Mandatory conditions of PWHT, See Notes (1), (2) of Table UCS-56ASME Section VIII-Division 1; Preheating from Appendix R (a) Demo F (Demo C) for material which has either a specified minimum tensile strength inexcess of 60,000 psi (410 MPa) or a thickness at the joint in excess of 1/2 in. (13 mm);(b) Demo F (Demo C) for all other materials of P-No. 4 group.ASME Section I; Mandatory Requirements for PWHT of Table PW-39 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal):Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm) to 5 in. (125 mm); 1 hr/in. (2 min/mm)Over 5 in. (125 mm); 5 hr plus 15 min for each additional inch over 5 in. (125 mm)Heating rate: The weldment shall be heated slowly to the holding temperature, Min. Demo F (Demo C)/hrCooling rate: Cool slowly in a still atmosphere to a temperature not exceeding Demo F (Demo C) For Non-Mandatory conditions of PWHT, See Notes (1), (2) of Table PW-39ASME Section I; Preheating from Appendix A (A-100) (a) Demo F (Demo C) for material which has either a specified minimum tensile strength inexcess of 60,000 psi (410 MPa) or a thickness at the joint in excess of 1/2 in. (13 mm);(b) Demo F (Demo C) for all other materials of P-No. 4 group.ASME B31.1; Requirements for PWHT of Table 132 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended value, See Clause 132.2Heating and Cooling Rate: Demo F (Demo C) per hr divided by 1/2 the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C) per hrHolding Time Based on Nominal Thickness: Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)For Non-Mandatory conditions of PWHT, See Note (A) of Table 132ASME B31.1; Preheating from Clause 131.42Demo F (Demo C) for materials of P-No. 4 group.ASME B31.3; Requirements for PWHT of Table 331.1.1 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended valueHolding Time Based on Nominal Thickness: Over 1/2 in. (13 mm); 1 hr/in (2.4 min/mm), 2 hr Min.Up to 1/2 in. (13 mm), if Min. T. S. is greater than 71 ksi (490 MPa):1 hr/in (2.4 min/mm), 2 hr Min.PWHT for thickness up to 1/2 in. (13 mm) is not required, when Min. Tensile Strength is up to 71 ksi (490 MPa) for P-No. 4 group.ASME B31.3; Preheating from Table 330.1.1 Demo F (Demo C) for P-No. 4 group.5A1ASME Section VIII-Division 1; Requirements for PWHT of Table UCS-56 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal): Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm) to 5 in. (125 mm); 1 hr/in. (2 min/mm)Over 5 in. (125 mm); 5 hr plus 15 min for each additional inch over 5 in. (125 mm)Heating and Cooling rate: Max. Demo F (Demo C) per hr divided by the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C)/hr; Min. Demo F (Demo C)/hrFor Non-Mandatory conditions of PWHT, See Notes (1), (2) of Table UCS-56For PWHT at lower temperatures for longer periods of time, See Note (3) of Table UCS-56ASME Section VIII-Division 1; Preheating from Appendix R(a) Demo F (Demo C) for material which has either a specified minimum tensile strength inexcess of 60,000 psi (410 MPa) or has both a specified minimum chromium content above 6.0% and a thickness at the joint in excess of 1/2 in. (13 mm); (b) Demo F (Demo C) for all other materials of P-No. 5A group.ASME Section I; Mandatory Requirements for PWHT of Table PW-39 Min. Holding Temperature; Demo F (Demo C) Min. Holding Time for Weld Thickness (Nominal): Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm) to 5 in. (125 mm); 1 hr/in. (2 min/mm)Over 5 in. (125 mm); 5 hr plus 15 min for each additional inch over 5 in. (125 mm)Heating rate: The weldment shall be heated slowly to the holding temperature, Min. Demo F (Demo C)/hrCooling rate: Cool slowly in a still atmosphere to a temperature not exceeding Demo F (Demo C) For Non-Mandatory conditions of PWHT, See Notes (1), (2), (3) of Table PW-39ASME Section I; Preheating from Appendix A (A-100) (a) Demo F (Demo C) for material which has either a specified minimum tensile strength inexcess of 60,000 psi (410 MPa) or has both a specified minimum chromium content above 6.0% and a thickness at the joint in excess of 1/2 in. (13 mm); (b) Demo F (Demo C) for all other materials of P-No. 5A group.ASME B31.1; Requirements for PWHT of Table 132 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended value, See Clause 132.2Heating and Cooling Rate: Demo F (Demo C) per hr divided by 1/2 the maximum thicknessof material in inches at the weld, but no more than Demo F (Demo C) per hrHolding Time Based on Nominal Thickness: Up to 2 in. (50 mm); 1 hr/in. (2 min/mm), 15 min Min.Over 2 in. (50 mm); 2 hr plus 15 min for each additional inch over 2 in. (50 mm)For Non-Mandatory conditions of PWHT, See Note (A) of Table 132ASME B31.1; Preheating from Clause 131.4(a) Demo F (Demo C) for material which has either a specified minimum tensile strength inexcess of 60,000 psi (410 MPa) or has both a specified minimum chromium content above 6.0% and a thickness at the joint in excess of 1/2 in. (13 mm); (b) Demo F (Demo C) for all other materials of P-No. 5A group.ASME B31.3; Requirements for PWHT of Table 331.1.1 Holding Temperature Range; Demo F (Demo C) to Demo F (Demo C)Upper limit temperature range is a recommended valueHolding Time Based on Nominal Thickness: For all Nominal Thickness sizes, if > 3% Cr and > 0.15% C:1 hr/in (2.4 min/mm), 2 hr Min.Over 1/2 in. (13 mm), if