ASME Section IX Quick Review on Essential Variables Green=update ASME 2010-2011a 1-Guide (Preheat)
The need for and the temperature of preheat are dependent upon a number of factors such as chemical analysis, degree of restraint of the p arts being joined, elevated temperature mechanical properties, and material thicknesses. When welding two different P-Number materials, the minimum preheat temperature required shall be the higher temperature temperature for the material material to be welded. Also, thickness referred to for the minimum preheat is the greater of the nominal thicknesses at the weld of the parts to be joined. ASME Section IX, QW-406.1: A decrease of more than 100 °F (55 °C) in the preheat temperature qualified needs a re-qualification, for these processes: SMAW, SAW, GMAW, FCAW, GTAW, PAW, EBW, LBW, and Stud Welding. Note: The minimum temperature for welding shall be specified in the WPS. 2-Guide (Postweld Heat Treatment)
When pressure parts of two different P-Number groups are joined by welding, the PWHT shall be that specified according to ASME Table and applicable notes for the material requiring the higher PWHT temperature. When a non-pressure part is welded to a pressure part, and PWHT is required for either part, heat treatment temperature of pressure parts shall control. 1) In Tables ASME Section I and VIII Div. 1, the term thickness governing PWHT, is the thickness of the weld or the thinner of the sections being joined, whichever is least. For fillet welds, the nominal thickness is the throat thickness, and for partial penetration and material repair welds, the nominal thickness is the depth of the weld groove or preparation; p reparation; for clad, the total thickness of the material, including the clad and weld deposit overlay. For combination groove and fillet welds, nominal thickness is either the depth of the groove weld or the fillet throat dimension, whichever is greater. 2) In Tables ASME B31.1 and B31.3, the term nominal thickness (T) governing PWHT, is: For B31.3, T refers to thicker component measured at the joint, except that for branch and fillet weld connections, See details in Clause 331 .1 For B31.1, T refers to the lesser thickness of (A) the thickness of the weld or (B) the thicker of the materials being joined at the weld. For definition of thickness of the weld for branch welds, See details in Clause 132.4.2
3-Guide (Heat input)
ASME Section IX, QW-409.1: An increase in heat input or an increase in volume of weld metal deposited per unit length of weld, over that qualified is Supplementary Essential variable for SAW, GTAW, SMAW, FCAW, GMAW and EGW process, and therefore needs re-qualification for impacted test applications only.
The increase shall be determined by (a), (b), or (c) for nonwaveform controlled welding, or by (b) or (c) for waveform controlled welding (See Non-mandatory Appendix H): (a) Heat input [J /in. (J/mm)] = (Voltage x Amperage x 60)/ Travel Speed [in./min (mm/min)] (b) Volume of weld metal measured by (1) an increase in bead size (width x thickness), or (2) a decrease in length of weld bead per unit length of electrode (c) By measurements of instantaneous energy or power : Heat input [J /in. (J/mm)] = Energy (J)/ Weld Bead Length [in. (mm)] Heat input [J /in. (J/mm)] = Power (J/s or W) x arc time (s)/ Weld Bead Length [in. (mm)]
The requirement for measuring the heat input or volume of deposited weld metal does not apply when the WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding. 4-Guide (Joints) Sketches, Production Drawings, Weld Symbols or Written Description should show the general arrangement of the parts to be welded. Where applicable, the root spacing and the details of weld groove may be specified. At the option of the Manufacturer, sketches may be attached to illustrate joint design, weld layers and bead sequence, e.g., for notch toughness procedures, for multiple process procedures, etc. Type and Dimensions of Groove Welds of Test Coupon for PQR: ASME Section IX, QW-211: Qualification in plate also qualifies for pipe welding and vice versa. The dimensions of the test coupon shall be sufficient to provide the required test specimens. ASME Section IX, QW-212: Except as otherwise provided in QW-250, the type and dimensions of the welding groove are not essential variables.
For combination qualifications, the deposited weld metal thickness shall be recorded for each filler metal or process used. ASME Section IX, QW-402.1: A change in the type of groove (Vee groove, U-groove, single-bevel, double-bevel, etc.) is not essential variable for OFW, SMAW, SAW, GMAW, FCAW, GTAW, ESW and EGW process.
ASME Section IX, QW-202.2 Groove and Fillet Welds: Qualification for Groove Full Penetration Welds, Partial Penetration Groove Welds, and Fillet Welds. 5-Guide (Position) ASME Section IX, QW-203: Unless specifically required otherwise by the welding variables (QW-250), a qualification in any position qualifies the procedure for all positions. The welding process and electrodes must be suitable for all positions permitted by the WPS. Nonessential for OFW, SMAW, GMAW, FCAW, GTAW, SAW, PAW process: ASME Section IX, QW-405.1: The addition of other welding positions than those already qualified. Nonessential for SMAW, GMAW, FCAW, GTAW, PAW process: ASME Section IX, QW-405.3: A change from upward to downward, or from downward to upward, in the progression specified for any pass of a vertical weld, except that the cover or wash pass may be up or down. The root pass may also be run either up or down when the root pass is removed to sound weld metal in the preparation for welding the second side. Supplementary Essential for SMAW, GMAW, FCAW, GTAW, PAW process: ASME Section IX, QW-405.2: A change from any position to the vertical position uphill progression. Vertical-uphill progression (e.g., 3G, 5G, or 6G position) for PQR, qualifies WPS for all positions. In uphill progression, a change from stringer bead to weave bead. Note: Supplementary essential variables are required for metals for which other Sections specify notch-toughness tests and are in addition to the essential variables for each welding process. 6-Guide (Filler Metal) ASME Section IX, QW-250: Filler metal categories (F-No. and A-No.) are essential variables. For Non-impacted test applications only, filler metal classification within an SFA specification with the same F-No. and the same A-No. and the same minimum tensile strength and the same nominal chemical composition can be used with the same WPS. ASME Section IX, QW-404.12: For impacted test applications only, following changes in filler metals need a re-qualification: a change in filler metal classification within an SFA specification, or for a filler metal not covered by an SFA specification or a filler metal with a “G” suffix within an SFA specification, a change in the trade designation of the filler metal.
Any electrode diameter sizes can be used in WPS, as it is not an essential variable for most process. (ASME Section IX, QW-250) For combination qualifications, the deposited weld metal thickness shall be recorded for each filler metal or process used.
7-Guide (Thickness of Base Metal Range) See revision for 2011 in green T: Thickness of Test Coupon Welded
T less than 1/16 in. (1.5 mm): Qualified Thickness Range: T Min., 2T Max. [For GMAW-Short Circuit Arc: 1.1T Max. ASME IX, QW-403.10]
T from 1/16 in. to 3/8 in. (1.5 mm to 10 mm), incl.: Qualified Thickness Range: 1/16 in. (1.5 mm) Min., 2T Max. [For GMAW-Short Circuit Arc: 1.1T Max. ASME IX, QW-403.10] [For ferrous base metals other than P-No. 7, 8 and 45 (when test coupon receives a PWHT above the upper transformation temperature or a solution heat treatment for P-No. 10H materials): 1.1T Max. ASME IX, QW-407.4 ] [For impact test application, except ESW process: Min. Qualified Thickness is either a) T when T is 1/4 in. (6 mm) up to 3/8 in. (10 mm) or b) 1/2T Min. when T is less than 1/4 in. (6 mm); This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding. ASME IX, QW-403.6 ] T over 3/8 in. (10 mm), but less than 1-1/2 in. (38 mm): Qualified Thickness Range: 3/16 in. (5 mm) Min., 2T Max. [For GMAW-Short Circuit Arc, when T is less than 1/2 in. (13 mm): 1.1T Max. ASME IX, QW-403.10] [For any weld pass greater than 1/2 in. (13 mm) thick: 1.1T Max. (Except GTAW process). ASME IX, QW-403.9 ] [For ferrous base metals other than P-No. 7, 8 and 45 (when test coupon receives a PWHT above the upper transformation temperature or a solution heat treatment for P-No. 10H materials): 1.1T Max. ASME IX, QW-407.4 ] [For impact test application, except ESW process: Min. Qualified Thickness is either T or 5/8 in. (16 mm), whichever is less; This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding. ASME IX, QW-403.6 ] T from 1-1/2 in. (38 mm) to 6 in. (150 mm), incl.: Qualified Thickness Range: 3/16 in. (5 mm) Min., 8 in. (200 mm) *** Max. (***For SMAW, SAW, GMAW, FCAW, PAW, and GTAW on ly; otherwise 2T Max.) [When testing longitudinal-bend tests only: 2T Max.] [For any weld pass greater than 1/2 in. (13 mm) thick: 1.1T Max. (Except GTAW process). ASME IX, QW-403.9 ] [For ferrous base metals other than P-No. 7, 8 and 45 (when test coupon receives a PWHT above the upper transformation temperature or a solution heat treatment for P-No. 10H materials): 1.1T Max. ASME IX, QW-407.4 ] [For impact test application, except ESW process: Min. Qualified Thickness is 5/8 in. (16 mm); This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding. ASME IX, QW-403.6 ] T over 6 in. (150 mm): Qualified Thickness Range: 3/16 in. (5 mm) Min., 1.33T Max.
[When testing longitudinal-bend tests only: 2T Max.] [For any weld pass greater than 1/2 in. (13 mm) thick: 1.1T Max. (Except GTAW process). ASME IX, QW-403.9 ] [For ferrous base metals other than P-No. 7, 8 and 45 (when test coupon receives a PWHT above the upper transformation temperature or a solution heat treatment for P-No. 10H materials): 1.1T Max. ASME IX, QW-407.4 ] [For impact test application, except ESW process: Min. Qualified Thickness is 5/8 in. (16 mm); This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding. ASME IX, QW-403.6 ]
See Notes of Table QW-451.1 of ASME Section IX , for restriction on qualified thickness range for short-circuiting transfer mode of GMAW process, etc.; also when testing longitudinal-bend tests only {T over 3/8 in. (10 mm)}, 2T Max. for all of the above T ranges, See Table QW-451.2 ASME Section IX, QW- QW-403.6 (Supplementary Essential Variable-T Limits impact test): For impact test applications only: The minimum base metal thickness qualified is the thickness of the test coupon T or 5/8 in. (16 mm), whichever is less. However, where T is less than ¼ in. (6 mm), the minimum thickness qualified is 1/2T. This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic material or P-No. 10H is solution annealed after welding. Note: This applies to SMAW, SAW, FCAW, GMAW, GTAW, PAW, and EGW process.
[For impact test application: Min. Qualified Thickness is either a) T o r 5/8 in. (16 mm), whichever is less or b) 1/2T Min. when T is less than 1/4 in. (6 mm)] ASME Section IX, QW-407.4 (Essential Variable-T Limits): For ferrous base metals other than P-No. 7, P-No. 8, and P-No. 45, when a procedure qualification test coupon receives a PWHT above the upper transformation temperature or a solution heat treatment for P-No. 10H materials, the maximum qualified base metal thickness, T, shall not exceed 1.1 times the thickness of the test coupon. Note: This applies to SMAW, SAW, FCAW, GMAW, GTAW, PAW, ESW, and EGW process. ASME Section IX, QW-403.10 (Essential Variable-T Limits-GMAW-S. cir. arc): For short-circuiting transfer mode of the gas metal-arc process, when the qualification test coupon thickness is less than ½ in. (13 mm), the maximum qualified base metal thickness, T, shall not exceed 1.1 times the thickness of the qualification test coupon. For thicknesses of ½ in. (13 mm) and greater, use Table QW-451.1 or Table QW-451.2, as applicable.
(For GMAW-Short Circuit Arc, when T is less than 1/2 in. (13 mm): 1.1T Max.) ASME Section IX, QW-403.9 (Essential Variable-t pass > ½ in. (13 mm)): For single pass or multipass welding in which any pass is greater than 1/2 in. (13 mm) thick, the maximum qualified base metal thickness, T, shall not exceed 1.1 times the thickness of the qualification test coupon. Note: This applies to SMAW, SAW, FCAW, GMAW, ESW, and EGW
(For single or multipass welding in which any pass is greater than 1/2 in. (13 mm) thick: 3/16 in. (5 mm) Min., 1.1T Max.) ASME Section IX, QW-403.2(Essential Variable-T Limits-OFW): For OFW process, the maximum thickness qualified is the thickness of test coupon. ASME Section IX, QW-211: Qualification in plate also qualifies for pipe welding and vice versa. The dimensions of the test coupon shall be sufficient to provide the required test specimens. Qualified Diameter Range: All Nominal Pipe (Tube) Sizes. FILLET-WELDS Qualified Range is all fillet sizes on all base metal thicknesses and all diameters as per Table QW-451 8-Guide (Thickness of Weld Metal Range) T: Thickness of Test Coupon Welded
T less than 3/4 in. (19 mm): Qualified Deposited Weld Metal Thickness t: 2t Max. [ASME IX, QW-404.32: For GMAW-Short Circuit Arc, when t is less than 1/2 in. (13 mm): 1.1t Max.] T from 3/4 in. (19 mm) to less than 1-1/2 in. (38 mm): Qualified Deposited Weld Metal Thickness t: 2t when t < 3/4 in. (19 mm) and 2T when t >= 3/4 in. (19 mm) [ASME IX, QW-404.32: For GMAW-Short Circuit Arc, when t is less than 1/2 in. (13 mm): 1.1t Max.] [When testing longitudinal-bend tests only: 2t Max.] T from1-1/2 in. (38 mm) to 6 in. (150 mm), incl.: Qualified Deposited Weld Metal Thickness t: 2t when t < 3/4 in. (19 mm) and 8 in. (200 mm) *** when t >= 3/4 in. (19 mm) (***For SMAW, SAW, GMAW, FCAW, PAW, and GTAW on ly; otherwise 2t Max.) [ASME IX, QW-404.32: For GMAW-Short Circuit Arc, when t is less than 1/2 in. (13 mm): 1.1t Max.] [When testing longitudinal-bend tests only: 2t Max.] T over 6 in. (150 mm): Qualified Deposited Weld Metal Thickness t: 2t when t < 3/4 in. (19 mm) and 1.33T when t >= 3/4 in. (19 mm) [ASME IX, QW-404.32: For GMAW-Short Circuit Arc, when t is less than 1/2 in. (13 mm): 1.1t Max.] [When testing longitudinal-bend tests only: 2t Max.]
See Notes of Table QW-451.2 of ASME Section IX , for restriction on qualified thickness range for short-circuiting transfer mode of GMAW process, etc.; also when testing longitudinal-bend tests only 2t for all of the abo ve T ranges, See Table QW-451.2
ASME Section IX, QW-404.32 (Essential Variable-t Limits-GMAW-S. cir. arc): For short-circuiting transfer mode of the gas metal-arc process, when the depo sited weld metal thickness is less than ½ in. (13 mm), the maximum qualified deposited weld metal thickness, t, shall not exceed 1.1 times that of the qualification test deposited weld metal thickness. For weld metal thicknesses of ½ in. (13 mm) and greater, use Table QW-451.1, Table QW-451.2, or Table QW-452.1, as applicable.
(For GMAW-Short Circuit Arc, when t is less than 1/2 in. (13 mm): 1.1t Max.) FILLET-WELDS Qualified Range is all fillet sizes on all base metal thicknesses and all diameters as per Table QW-451 9-Guide (Base Metals) QW-420 (2011a): Please note that for materials listed in QW/QB-422 (also in our database), only those that have a specified minimum tensile strength shall be used for groove weld procedure qualification test coupons. QW-420 (2011a): If an unlisted base metal has the same UNS number designation as a base metal listed in QW/QB-422 (our database), that base metal is also assigned that P Number or P-Number plus Group Number. If the unlisted base metal is used for procedure qualification, the minimum tensile value of the listed base metal shall apply for the tension test specimens.
ASME Section IX, QW-424 Base Metal (s) with the same P-No. Used for PQR Qualify WPS for any metals of the same P-No. In addition: (P-No. 3 metals also qualify any P-No. 3 to P-No. 3 or 1) (P-No. 4 metals also qualify any P-No. 4 to P-No. 4, 3 or 1) (P-No. 5A metals also qualify any P-No. 5A to P-No. 5A, 4, 3 or 1) (P-No. 15E metals also qualify any P-No. 15E or 5B to P-No. 15E or 5B)
Base Metal (s) with a different P-No. Used for PQR Qualify WPS for any metals of the first to any metals of the second P-No. In addition:
One metal from P-No. 5A to a metal from P-No. 4, 3 or 1 Qualify any metals from P-No. 5A to any metals from P-No. 4, 3 or 1
One metal from P-No. 4 to a metal from P-No. 3 or 1 Qualify any metals from P-No. 4 to any metals from P-No. 3 or 1
One metal from P-No. 15E to a metal from any other P-No. Qualify any metals from P-No. 15E or 5B to any metals from the second P-No. Unassigned metals : metals that do not appear in table QW/QB-422 are considered to be unassigned metals except as otherwise defined for base metals having the same UNS
Any unassigned metal to the same unassigned metal Qualify the unassigned metal to itself Any unassigned metal to any metal with P-No. Qualify the unassigned metal to any metals from the same P-No. Any unassigned metal to any metal from P-No. 15E Qualify the unassigned metal to any metals from P-No. 15E or 5B Any unassigned metal to any other unassigned metal Qualify first unassigned metal to the second unassigned metal
