WPS vs PQR — What Each Document Does and When You Need Both
A WPS tells the Soldador what to do. A PQR proves the WPS works. D1.1 Cláusula 5 allows Precalificado WPSs without a PQR. Clause 6 requires a PQR for any WPS that falls outside prequalified Límites. Most Acero estructural Fabricación uses prequalified WPSs and never needs a PQR.
Side-by-Side Comparison
| Property | WPS | PQR |
|---|---|---|
| Purpose | Welding instruction document | Qualification test record |
| Who creates | Fabricator | Fabricator or Ensayo lab |
| When required | Always | Only when Clause 6 qualification needed |
| D1.1 clause | 5 (prequalified) or 6 (qualified) | 6 only |
| Content | Parameter ranges and limits | Actual test parameters and results |
| Number needed | One per joint configuration | One per qualification test |
| Signed by | Fabricator authorized representative | Fabricator authorized representative |
| Valid indefinitely? | Yes, until variables change | Yes, unless process changes |
What a WPS Contains
A Especificación del Procedimiento de Soldadura is the instruction document that tells the welder exactly how to make a Soldadura. Every WPS specifies the essential variables that control weld quality. For prequalified WPSs, Tabla 5.5 lists the required variables. For qualified WPSs, Table 6.6 defines the essential variables that must be recorded.
The essential variables common to both prequalified and qualified WPSs include the welding process (SMAW, GMAW, FCAW, or SAW), base metal group and Rango de espesor, filler metal classification and Tamaño, welding position, preheat and interpass temperature, joint design (groove type, angle, Apertura de raíz, Respaldo), and electrical parameters (Tipo de corriente, Polaridad, Voltaje range, Velocidad de alimentación del alambre or Amperaje range).
A EPS precalificada must conform to all the Requisitos of Clause 5. This means the Detalle de la junta must match one of the prequalified joint configurations in Figure 5.1, the Metal Base must appear in Table 5.6, the Metal de Aporte must comply with Table 5.7, and Precalentamiento must meet Table 5.11. If all requirements are met, the WPS is valid without any testing.
A prequalified WPS is not a shortcut. It must comply with every requirement in Clause 5, including Tables 5.1, 5.3, 5.4, 5.5, 5.6, 5.7, 5.11, and Figure 5.1. Missing any single requirement means the WPS must be qualified by testing under Clause 6.
What a PQR Contains
A Registro de Calificación de Procedimiento documents the actual Soldadura de prueba parameters used during qualification and the results of destructive testing performed on the test specimens. Unlike a WPS, which specifies ranges, a PQR records the exact values used during the test weld.
The PQR includes the actual Soldadura parameters (amperage, voltage, Velocidad de Avance, wire feed speed), the base metal Especificación and Espesor, the filler metal lot and classification, preheat and interpass temperatures measured during the test, and the joint configuration welded. These actual parameters establish the baseline from which the qualified range is determined.
Destructive test results form the core of the PQR. D1.1 Clause 6 requires specific tests depending on the joint type.
For groove welds, the required tests include bend tests (face bends, root bends, or side bends depending on thickness), tensile tests (reduced-section tension specimens to Verificar Mínimo tensile Resistencia), and macro etch examination (cross-sections examined for soundness, fusion, and profiles). The specimen locations are specified in D1.1 Clause 6 figures based on plate thickness and joint type.
All test results must meet the Criterios de aceptación in Clause 6. Bend specimens must show no Fisuras or open discontinuities exceeding 1/8 inch. Tensile specimens must meet the minimum tensile strength of the base metal. Macro etch specimens must show complete fusion and acceptable profiles.
The Prequalified Path
D1.1 Clause 5 provides a prequalified path that eliminates the need for PQR testing entirely. A prequalified WPS is one that uses only parameters and configurations that D1.1 has already deemed acceptable based on decades of industry experience and testing. The prequalified path exists because certain process, material, and joint combinations have been proven through widespread successful use.
To use the prequalified path, every element of the WPS must comply with the requirements of Clause 5. The Proceso de Soldadura must be one of the four prequalified processes listed in Table 5.1: SMAW, SAW, GMAW (except short-circuit transfer), or FCAW. The base metal must appear in Table 5.6, which lists approved base metals by group.
The filler metal must match the Grupo de metal base per Table 5.7. The joint detail must be one of the prequalified configurations in Figure 5.1. Preheat must meet the minimum temperatures in Table 5.11 based on the material group, thickness, and hydrogen Categoría.
Additional prequalified requirements include WPS limitations from Table 5.3 and Table 5.4 (Máximo Electrodo diameters, maximum pass sizes, maximum single-pass fillet sizes by position), and the Variable esencial requirements of Table 5.5.
Every table must be satisfied. Failing to meet even one prequalified requirement means the WPS must be qualified by testing under Clause 6, which requires a PQR.
The advantage of the prequalified path is significant: no test welds, no Ensayo destructivo, no laboratory costs, and no wait time. The Fabricante writes the WPS, verifies Cumplimiento with all Clause 5 tables, and the WPS is ready to use. Most structural steel fabrication in the United States follows this path.
When You Need a PQR
A PQR is required whenever the WPS falls outside the prequalified limits of Clause 5. The most common situations that trigger Ensayo de calificación include:
GMAW short-circuit transfer (GMAW-S): Table 5.3 specifies that the mode of transfer is not short circuit. Any WPS using GMAW-S must be qualified by testing per Clause 6, producing a PQR.
Non-prequalified joint configurations: If the joint detail does not match any configuration in Figure 5.1, or if the fabricator wants to modify a prequalified joint beyond the allowed tolerances, qualification testing is required. Custom groove angles, non-Norma root openings, and unique backing configurations all fall outside prequalified limits.
Base metals not listed in Table 5.6: If the steel grade or specification does not appear in Table 5.6, the base metal is not prequalified regardless of the process or Diseño de junta. High-strength steels, weathering steels not in the table, and proprietary grades all require qualification.
ASME IX work: Unlike D1.1, ASME Boiler and Pressure Vessel Código Section IX has no prequalified path. Every WPS used under ASME IX must be supported by a PQR, regardless of how common the process, material, or joint configuration may be. Fabricators working to both codes often have PQRs for ASME work and prequalified WPSs for D1.1 work.
Parameters outside prequalified ranges: Exceeding the maximum electrode sizes in Table 5.3, the maximum pass sizes in Table 5.4, or using parameters outside the ranges specified in Table 5.5 all require qualification testing.
The most common trigger for PQR testing in structural steel work is GMAW-S. Many fabricators use short-circuit transfer for thin material and root passes, and every GMAW-S application requires a qualified WPS supported by a PQR.
One PQR, Multiple WPSs
A single PQR establishes a range of qualified variables, not a single set of parameters. The qualified range is determined by the rules in D1.1 Clause 6 and the supplementary tables (particularly Table 6.8 for thickness ranges). Any WPS that falls within the qualified ranges established by a PQR can reference that PQR as its supporting documentation.
For example, a PQR qualified at 1 inch plate thickness with FCAW on A36 steel using E71T-1 filler metal qualifies a thickness range from 1/8 inch to 2 inches per Table 6.8. The fabricator can write separate WPSs for 3/8 inch fillet welds, 3/4 inch groove welds, and 1-1/2 inch groove welds, all referencing the same PQR, as long as every essential variable in each WPS falls within the qualified range.
This one-to-many relationship is a key efficiency in qualification management. A well-planned qualification test program can produce a small number of PQRs that support dozens of production WPSs.
The essential variables that define the qualified range include process, base metal group, Clasificación del metal de aporte, position, thickness range, and electrical characteristics. Changing any essential variable beyond the qualified range requires a new PQR.
Fabricators typically maintain a PQR library covering their standard processes and materials. Before writing a new WPS, they check whether an existing PQR already covers the required parameters. If it does, the new WPS references the existing PQR and no additional testing is needed. If no existing PQR covers the parameters, a new qualification test is scheduled.
Frequently Asked Questions
No. D1.1 Clause 5 provides a prequalified path where WPSs that meet all requirements of Clause 5 are exempt from the qualification testing that produces a PQR. If your WPS uses a prequalified process (SMAW, SAW, GMAW except short-circuit, or FCAW), a base metal from Table 5.6, a filler metal per Table 5.7, a joint detail from Figure 5.1, and preheat per Table 5.11, no PQR is required. Most structural steel fabrication uses prequalified WPSs.
Yes. A single PQR establishes a range of qualified variables. Any WPS that falls within those qualified ranges can reference that PQR. For example, a PQR qualified at 1 inch thickness with FCAW on A36 steel can support WPSs for thicknesses from 1/8 inch through 2 inches (the qualified range per Table 6.8). Multiple WPSs with different joint details can reference the same PQR if all essential variables remain within the qualified range.
A WPS is written by the fabricator for a specific application. A Standard Welding Procedure Specification (SWPS) is a pre-tested, published WPS available from AWS that can be used without additional qualification testing. SWPSs are listed in D1.1 Annex L and cover common structural applications. Using an SWPS eliminates both the need to write a WPS from scratch and the need for a PQR, but the SWPS must be used exactly as published without modification.
The fabricator or contractor is responsible for the PQR. D1.1 requires that the individual responsible for welding operations sign the PQR, attesting that the test weld was made in accordance with the WPS and that the test results meet the acceptance criteria of Clause 6. The testing laboratory provides the test data, but the fabricator assumes responsibility for the qualification record.
D1.1:2025 assigns WPS responsibility to the Contractor (fabricator or erector). The Contractor shall prepare a written WPS specifying all applicable essential variables. The Engineer approves the WPS but does not write it. This distinction matters because the Contractor has direct knowledge of their equipment, personnel qualifications, and shop practices — the WPS must reflect actual welding conditions, not theoretical parameters.