Thickness limit of Welder qualification test (WQT)
The welder qualification test (WQT) thickness limit depends on the deposited weld metal on the test coupon, by the welder. It does not depend on the base metal, only the welding procedure specification (WPS) test thickness limit depends on the base metal.
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| Thickness limit of WQT. |
American society of mechanical engineering, Boiler, and pressure vessel code (ASME BPVC sec IX), provides guidelines for the welder qualification test (WQT) thickness range up to which a welder can weld. It can found in table QW-452.1(b) of ASME SEC-IX. A simplified table is given below,-
Table QW-452.1(b)
NOTES:
(1) When more than one welders and or more than one processes and more than one filler metals, F‐Number is used to deposited weld metal in the test coupon, the thicknesses, t, of the weld metal deposition in the test coupon deposited by each welder with each process and each filler metal F‐Number in accordance with the applicable variables under table QW-404 (See below) shall be determined and used individually in the thickness ‘t’, of Weld Metal deposition in the Coupon, column to determine the “Thickness of Weld Metal Qualified.”
(2) When a two or more pipe of test coupons with the different weld metals thicknesses may be used to determine the weld metals thickness qualified, and that of the thickness may be applied to productions of the weld to the smallest diameter, for which the welders are qualified in accordance with Table QW-452.3 (See below).
(3) The thickness of the test coupon of 19 mm or over shall be used for qualifying a combination of three or more welders, each of whom may use the same or a different welding process.
Explanation:
* If the welder qualified deposited weld metal is "t" then they which can weld "2t", but there are no criteria for minimum thickness in ASME.
* If the welder weld or deposited welding on test coupon more than 13 mm within a minimum 3 layers, in this case, the welder qualify for unlimited thickness. But there are no criteria for minimum thickness in ASME.
FILLER METALS
* An increase of greater than 10 percent in the cross‐section area of the filler metal added or in the wire‐feed speed beyond that qualified.
* The decrease in the thicknesses or change in nominal specified chemical analysis of weld metals buttering beyond that qualified.
* When a change in the size of the filler metal.
* A changes from one F‐Number in table QW-432 to in any other F‐Number or to any other filler metals don't list in Table QW-432.
* (Applicable only to ferrous metals.) Changes in the chemical compositions of the weld deposited from one A‐Number to any other A‐Number in the table QW-442. Qualification with A‐No. 1 shall qualify for A‐No. 2 and vice versa. The weld metals chemical compositions may be determined by any of the following:
(a) For all welding processes from the chemical analysis of the weld deposition taken from the procedure qualification test/ welder qualification test (WQT) coupon.
(b) For shielded metal arc welding (SMAW), LBW, PAW, and gas tungsten arc welding (GTAW), from the chemical analysis of the weld deposit prepared according to the filler metal specification, or from the chemical composition as reported either in the filler metal specifications or and the manufacturer’s or and supplier’s certificates of compliance.
(c) For gas metal arc welding (GMAW) and EGW, from the chemicals analysis of the weld deposition prepared according to the filler metal specifications or the manufacturer’s or and supplier’s certificates of compliance. when the shielding gas used was the same as that used to weld the procedure qualification test (PQT) coupon. 80 ASME BPVC.IX-2015
(d) For submerged arc welding (SAW), from the chemical analysis of the weld depositions prepared according to the filler metal specifications or the manufacturer’s or and supplier’s certificates of the compliance. when the flux used was the same as that used to weld the procedure qualification test/record coupon.
In lieu of A‐Number designations, the nominal chemical compositions of the weld depositions shall be indicated on the welding procedure specification (WPS) and on the procedure qualification record (PQR). The designations of the nominal chemical composition are may also be by reference to the American welding society (AWS) classification except for the suffix classifications, the manufacturer’s trade designations, or other established procurement documents.
* A change in the nominal size of the electrodes or electrodes specified in the welding procedure specifications (WPS).
* A change in the nominal diameter of the electrode to over 6 mm. This variable does not apply when a Welding procedure specification (WPS) is qualified with a Post weld heat treatment (PWHT) above the upper transformation temperature or when an austenitic material is a solution annealed after welding.
* Addition or deletion, or a change of more than 10 percent in the nominal amount or compositions of the supplementary deoxidation materials (in addition to filler metals) beyond that qualified.
(a) A change in the indicator for minimum tensile strength, when the flux wire combinations are classified in Sections II, Part C.
(b) A change in either the flux trades name or and wire trades name, when neither the flux nor the wire is classified in Sections II, Part C.
(c) A change in flux trades name, when the wire is classified in Section II, Part C, but the flux is not classified. A change in the wire classifications within the requirements of table QW-404.5 does not require requalification.
(d) A change in the flux's trade name for the A‐No. 8 deposit.
* Where the alloy content of the weld metal is largely dependents upon the composition of the flux used or any change in any part of the welding procedures, which would result in the important alloying elements in the weld metals being outside the specification range of chemistry given in the Welding Procedure Specification (WPS). If there is evidence that the production welds are not being made in accordance with the welding procedure specification (WPS), the authorized agency inspector may require a that a check be made on the chemical compositions of the weld metals. Such a check shall preferably be made on a production welds.
* A change in the 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.
When a filler metal conforms to a filler metal classification, within an SFA specification, except for the suffix classifications, requalification is not required if a change is made in any of the following:
(a) from filler metals that are designated as moisture‐resistant to one that is not designated as moisture‐resistant and vice versa (i.e., from E7018R to E7018)
(b) From the one diffusible hydrogen levels to another (ex., from E7018‐H8 to E7018‐H16)
(c) For carbon, stainless steel, low alloy, and filler metals having the same minimum tensile strength and the same nominal chemical compositions, a change from one low hydrogen coatings type to another low hydrogen coating type.
(d) From one position usability designations to the other for flux‐cored electrodes.
(e) From a classifications that require impact testing to the same classifications which have a suffix which indicates that impact testing was performed at a lower temperature or exhibited greater toughness at the required temperature or both, as compared to the classification which was used during the procedure qualification (ex., a change from E7018 to E7018‐1)
(f) From the classification qualified to another filler metals within the same SFA specifications, when the weld metals are exempt from Impact testing by other Sections. This exemption does not apply to the hard‐facing and corrosion‐resistant overlays.
* The deletion or additions of the filler metals.
* A change from one F‐Number in Table QW-432 to any other F‐Number or to any other filler metal, except as permitted in QW-433.
* A change in the type of flux or compositions of the flux.
* A change from the wire to plate electrodes, and vice versa.
* A change from the consumable guide to a non-consumable guide, and vice versa.
* Any change in the method by which filler metal is added, such as preplaced shim, top strip, wire, wire feed, or prior weld metal buttering of one or both joint faces.
* For filler metal additions, of any changes from the nominal specified analysis of the filler metals qualified.
* The omissions or additions of consumable inserts. Qualification in the single‐welded butt joints, with or without consumable inserts, qualifies for fillet welds and single‐welded butt joints with backing or double‐welded butt weld joints. Consumable inserts that conform to SFA-5.30, except that the chemicals analysis of the insert 81 ASME BPVC SEC.IX-2015, code conforms to analysis for any bare wires given in any SFA specification or American welding society (AWS) Classifications, shall be considered as having the same F‐Number as that bare wires as given in Table QW-432.
* A change from one of the following filler metals product forms to another:
(a) bare (solid or metal-cored)
(b) flux-cored
(c) flux coated (solid or metal-cored)
(d) powder
* The addition, or deletion, and change of more than 10 percent in the volume of supplementary filler metals.
* Where the alloy content of the weld metals is largely dependents upon the composition of the supplementary filler metals (including powder filler metals for PAW), any change in any part of the welding procedure specification (WPS) that would result in the important alloying elements in the weld metal being outside of the specification range of chemistry given in the Welding Procedure Specification (WPS).
* A change in the flux trade name and designations.
* A change in deposited weld metals thickness beyond that qualified in accordance with table QW-451 for procedure qualification record (PQR) or QW-452 for performance qualification, except as otherwise permitted in QW-303.1 and QW-303.2. When a welder is qualified using a volumetric examination, the maximum thickness stated in Table QW-452.1(b) applies.
* The maximum thicknesses qualified is the thickness of the test coupons.
* For the low voltage short‐circuiting type of gas metal‐arc process, when the deposited weld metals thickness is less than 13 mm, and an increase in deposited weld metals thickness beyond 1.1 times that of the qualifications test deposited weld metal thickness. For weld metals thicknesses of 13 mm and greater, use table QW-451.1, table QW-451.2, or tables QW-452.1(a) and QW-452.1(b), as applicable.
* A change in the filler metal classifications within SFA specifications, or, if not conforming to a filler metals classification within an SFA specification, a change in the manufacturer’s trade name for the filler metal. When optional supplemental designators, such as those which indicate moisture resistance, diffusible hydrogen, and supplemental impacts testing, are specified on the welding procedure specification (WPS), only filler metals which conform to the classifications with the optional supplemental designator specified on the welding procedure specification (WPS) shall be used.
* A change in flux type for the multilayer deposits in P‐No. 1 material.
* A change in the flux/wire classifications or a change in either the electrodes or fluxes trade name when the flux/wire combination is not classified to an SFA specification. Requalification is not required when a flux/wire combination conforms to an SFA specification and the change in classification is (a) from one diffusible hydrogen level to another, or (b) to a larger number in the indicator for impact toughness, indicating classifications at a lower impact testing temperature. These variables do not apply when the weld metal is exempt from impact testing by other Sections. These exemptions don't apply to the hard facing and corrosion‐resistant overlays.
* When flux from crushed slag is used, each batch or blend, as defined in SFA-5.01, shall be tested in accordance with ASME Section II, Part C by either the manufacturer or user or qualified as an unclassified flux in accordance with table QW-404.9.
* A change in the composition of the deposited weld metal from one A‐Number in table QW-442 to any other A‐Number, or to an analysis not listed in the table. A change in the UNS number for each American welding society (AWS) classification of A‐No. 8 or A‐No. 9 analysis of table QW-442, or each nonferrous alloy in table QW-432, shall require separate welding procedure specification (WPS) qualification. A‐Numbers may be determined in accordance with QW-404.5.
* A change in the diameter of the nominal electrodes used for the first layer of deposit.
* For submerged‐arc welding (SAW) and electro slag welding, a change in the nominal compositions or type of flux used. When the change in flux, not required for requalification.
* A change of more than 10 percent in the powdered metal feed rate recorded on the procedure qualification record (PQR).
* A change of more than 5 percent in the particle size range of the powder.
* A changes in the powdered metal particle size range recorded on the procedure qualification record (PQR).
* A change from homogeneous powdered metals to a mechanical mixed powdered metal or vice versa.
* A change in the form of filler metals from solid to the fabricated wire, flux-cored wire, powdered metal, or vice versa.
* A change in the powder feed rate range qualified. 82 ASME BPVC section.IX-2015.
* A change of more than 10 percent in the filler metals size and powder metal particle size.
* A change of more than 10 percent in the powder metal density.
* A change of more than 10 percent in the filler metals or powder metal feed rate.
* The addition or deletion of flux to the face of weld joints for the purpose of affecting weld penetrations.
* The method of controls of moisture pickup during storage and distributions for the shielded metal arc welding (SMAW) and gas metal arc welding (GMAW) ‐FC electrodes and flux for the submerged arc welding (SAW).
* A change in the diffusible hydrogen levels.
* The additions and deletions of filler metal and, when used, a change in the filler metal nominal composition.
* An increases in the deposited weld metals thickness qualified.
* An increases in the thickness or width of the preplaced filler metals.
* A change to another type or grade of replaced filler metal (type or grade are materials of the same nominal chemical analysis and mechanical property range, even though of different product forms).
* An increases in the nominal thickness and width of the electrode for strip filler metals used with the submerged arc welding (SAW) and ESW processes for corrosion-resistants and hard-facing weld metals overlay.
Table QW-452.3
Groove-Weld Diameter Limits
GENERAL NOTES:
(a) The types and numbers of tests required shall be in accordance with table QW-452.1.
(b) 73 mm Outside diameter (O.D). is the equivalent of nominal pipe size (NPS) 21 /2 (DN 65).
Explanation:
* If the welder qualifies less than 25 mm weld metal deposition on the test coupon, it means the welder can weld minimum size welded of the test coupon, and the maximum can unlimited.
* If the welder qualifies between 25 mm to 73 mm weld metal deposition on the test coupon, it means the welder can weld minimum size 25 mm and the maximum can be unlimited.
* If the welder qualifies over 73 mm weld metal deposition on the test coupon, it means the welder can weld minimum size weld (73 mm) of the test coupon and maximum can unlimited
Table QW-452.4
Small Diameter Fillet-Weld Test
GENERAL NOTES:
(a) The types and numbers of tests required shall be in accordance with the table QW-452.5.
(b) 73 mm, Outside Diameter (O.D) is considered the equivalent of nominal pipe size (NPS) 21 /2 (DN 65).
Explanation:
* If the welder qualifies less than 25 mm weld metal deposition on the test coupon, it means the welder can weld minimum, size welded of the test coupon and qualify for all thickness.
* If the welder qualifies between 25 mm to 73 mm weld metal deposition on the test coupon, it means the welder can weld minimum size 25 mm and qualify for all thickness.
* If the welder qualifies over 73 mm weld metal deposition on the test coupon, it means the welder can weld minimum size welded (73 mm) of the test coupon and qualify for all thickness.
Quick link for more details;
Shielded metal arc welding (SMAW) procedure variables
Gas tungsten arc welding (GTAW) procedure variables
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