3.2 Coupling and Supporting Multiple WPSs and PQRs

3.2 Coupling and Supporting Multiple WPSs and PQRs

Core Principle: Procedure qualification in ASME Section IX is modular. A single PQR may support dozens of distinct production WPSs across different positions, diameters, and joint configurations. Conversely, multiple PQRs can be coupled to support a single multi-process WPS (such as open-root GTAW with heavy-wall SMAW fill). However, the base metal and deposited weld metal thickness limits for each process must be calculated strictly in accordance with QW-200.4 and Table QW-451.1.

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1. The Modular Architecture of Procedure Qualification

A common misconception among candidates preparing for the AWS Endorsement exam is that every production WPS requires its own unique, dedicated PQR test coupon. ASME Section IX explicitly rejects this 1:1 restriction. Paragraphs QW-200.2(f) and QW-200.4 provide immense operational flexibility by permitting cross-referencing and modular coupling.

+-----------------------------------------------------------------------------------------+
|                         COUPLING COMBINATORIAL RELATIONSHIPS                            |
+-----------------------------------------------------------------------------------------+
|  ONE PQR --> MULTIPLE WPSs   | One comprehensive heavy-plate PQR supports:              |
|                              |  - WPS #1: Flat groove welding on plate                  |
|                              |  - WPS #2: All-position pipe welding                     |
|                              |  - WPS #3: Fillet welding of all sizes and thicknesses   |
|------------------------------+----------------------------------------------------------|
|  MULTIPLE PQRs --> ONE WPS   | Several focused PQRs combine to support one WPS:         |
|                              |  - PQR #1: Thin-sheet P-No. 1 qualification (1/16"-3/8") |
|                              |  - PQR #2: Heavy-plate P-No. 1 qualification (3/16"-2")  |
|                              |  --> Resulting WPS qualifies 1/16" through 2.0" thickness|
|------------------------------+----------------------------------------------------------|
|  MULTI-PROCESS COMBINATION   | Separate process records merge for combination joints:   |
|                              |  - PQR #A: GTAW open-root coupon (t = 1/4")              |
|                              |  - PQR #B: SMAW fill & cap coupon (t = 3/4")             |
|                              |  --> Resulting WPS: GTAW root + SMAW fill                |
+-----------------------------------------------------------------------------------------+

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2. One PQR Supporting Multiple WPSs

Under QW-200.2(f), a single PQR may be used to support several WPSs. Consider an organization that welds a 1.0-inch thick plate coupon using Shielded Metal Arc Welding (SMAW) with E7018 (F-No. 4) electrodes on ASTM A106 Grade B (P-No. 1 Group 1) material:

• Per Table QW-451.1, this 1.0-inch coupon qualifies a base metal thickness range of 3/16 inch to 2.0 inches (5 mm to 50 mm) and a deposited weld metal thickness of up to 2.0 inches (or 2T for t >= 3/4" with at least 3 passes).
• WPS #1 (Heavy Structural/Plate): Written for flat (1G) and horizontal (2G) plate welding with a 60-degree V-groove.
• WPS #2 (Pressure Piping): Written for all-position (6G/5G/2G) pipe butt welds from 3/16-inch wall up to 2.0-inch wall, on all pipe diameters (since diameter is not an essential variable for procedure qualification under QW-211).
• WPS #3 (Fillet Welds): Written for structural attachments, qualifying all fillet weld sizes on all thicknesses and diameters per QW-202.2(c).

All three WPSs reference the exact same PQR document number. The manufacturer is free to restrict operational ranges (such as specifying a narrower amperage window or tighter bevel angles) on individual WPSs without invalidating the parent PQR.

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3. Multiple PQRs Supporting a Single WPS

Conversely, an organization can synthesize multiple PQRs to support a broad-scope WPS. Common industry examples include:

1. Extended Thickness Coverage: Suppose a shop needs a WPS for P-No. 1 carbon steel covering 0.0625 in. (1.6 mm) up to 2.0 in. (50 mm). A 1.0-inch coupon qualifies 3/16 in. to 2.0 in., but fails to qualify thicknesses below 3/16 in. The shop can pair PQR #1 (welded on 1/8-inch coupon, qualifying 1/16 in. to 1/4 in.) with PQR #2 (welded on 1.0-inch coupon, qualifying 3/16 in. to 2.0 in.) to support a single WPS spanning 1/16 in. through 2.0 in.
2. Dissimilar Metal Combinations: PQR #1 qualifies P-No. 1 to P-No. 1. PQR #2 qualifies P-No. 8 to P-No. 8. However, welding a dissimilar joint between P-No. 1 and P-No. 8 requires a specific PQR welded between P-No. 1 and P-No. 8 per QW-424.1.

CODE MANDATE: Every essential variable across the entire scope of the combined WPS must be validated by the collective data of the supporting PQRs. If any single parameter (such as PWHT condition or filler metal F-Number) lacks supporting documentation in one of the PQRs, that portion of the WPS is invalid.

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4. Combination of Welding Procedures in a Single Joint (QW-200.4)

In power piping (ASME B31.1) and process piping (ASME B31.3), the most common joint configuration is a combination of two welding processes: Gas Tungsten Arc Welding (GTAW) for the root and hot pass, followed by Shielded Metal Arc Welding (SMAW) or Submerged Arc Welding (SAW) for the fill and cover passes.

Paragraph QW-200.4 establishes the governing rules for multi-process qualification:

QW-200.4(a): Supporting Options

A combination WPS may be supported by:

1. A single combination PQR coupon welded using all of the processes in the same joint, or
2. Multiple individual single-process PQR coupons welded separately, or
3. Any combination of the two.

QW-200.4(b): Thickness Limits for Multi-Process Joints

Understanding how thickness limits apply under QW-200.4(b) is paramount for the endorsement exam:

• Base Metal Thickness ($T$): The base metal thickness qualified for the combined WPS is governed by the total thickness of the coupon ($T$) per Table QW-451.1.
• Deposited Weld Metal Thickness ($t$): The maximum qualified deposited weld metal thickness for each individual process is governed strictly by the thickness of weld metal deposited by that specific process ($t_1, t_2$, etc.) on the test coupon.

+-----------------------------------------------------------------------------------------+
|               MATHEMATICAL BREAKDOWN: COMBINATION COUPON (QW-200.4(b))                  |
+-----------------------------------------------------------------------------------------+
| COUPON SPECIFICATION:                                                                   |
| - Total Base Metal Thickness (T): 1.0 in. (25.4 mm)                                     |
| - Process 1 (GTAW Root/Hot Pass): Deposited t_GTAW = 0.25 in. (6.35 mm)                 |
| - Process 2 (SMAW Fill/Cap):      Deposited t_SMAW = 0.75 in. (19.05 mm)                |
|                                                                                         |
| QUALIFIED RANGES FOR COMBINED PRODUCTION WPS (GTAW + SMAW):                             |
| 1. Base Metal Range (T):          3/16 in. to 2.0 in. (Table QW-451.1 for T = 1.0 in.)  |
| 2. Max Deposited GTAW (t_GTAW):   Up to 2 * t_GTAW = 2 * 0.25 = 0.50 in. (12.7 mm)      |
| 3. Max Deposited SMAW (t_SMAW):   Up to 2 * t_SMAW = 2 * 0.75 = 1.50 in. (or 2.0 in.    |
|                                   if 3+ passes qualify 2T per Note 1 of QW-451.1)       |
|                                                                                         |
| EXTRACTION: STAND-ALONE SINGLE-PROCESS WPS FOR GTAW ONLY:                               |
| - If the contractor writes a WPS using ONLY GTAW based on this combination PQR:         |
|   - Base Metal Range (T): LIMITED TO 2 * t_GTAW = 0.50 in. max per QW-200.4(b)!         |
|   - It does NOT qualify 2.0 in. base metal for GTAW alone, because GTAW was only        |
|     deposited on a 0.25 in. portion of the coupon.                                      |
+-----------------------------------------------------------------------------------------+

CRITICAL CODE CITATION: Under QW-200.4(b), when an individual process from a multi-process PQR is used in a single-process WPS, that process's base metal qualification is restricted to $2t$ (twice its own deposited thickness), rather than $2T$ (twice the coupon thickness), unless the coupon independently satisfies QW-451 base metal rules for that single process.

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5. Root Pass Qualification Without Backing

In piping fabrication, root passes are frequently welded without backing (open root). Under QW-402.4, the deletion of backing is an essential variable for most processes.

• Rule for Open-Root Qualification: If a procedure qualification coupon is welded without backing (open root), it qualifies production welding both with backing and without backing.
• Rule for Backed Coupons: If a coupon is welded with backing (e.g., steel backing ring, ceramic backing, or double-welded from both sides with backgouging), it qualifies production welding only with backing. It cannot be used to weld an open-root joint.
• Combined Procedure Root Pass: When qualifying a GTAW root pass followed by SMAW fill on an open-root joint, the GTAW process is qualified for open-root welding up to its qualified deposited thickness ($2t$). However, the SMAW process (deposited over the GTAW weld metal) was deposited with backing (the GTAW weld deposit served as backing for the SMAW). Therefore, the SMAW process is qualified to weld only with backing in production.

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6. Standard Welding Procedure Specifications (SWPSs) under Article V (QW-500)

In addition to qualifying proprietary WPSs via internal PQRs, ASME Section IX allows organizations to adopt pre-tested Standard Welding Procedure Specifications (SWPSs) published by the American Welding Society (AWS) and approved by ASME.

Scope and Legal Foundation (QW-500)

Mandatory Appendix E of ASME Section IX lists all approved AWS SWPSs (e.g., AWS B2.1-1-016 for standard carbon steel SMAW, AWS B2.1-1-207 for GTAW/SMAW piping). An organization adopting an SWPS is exempt from welding a full procedure qualification coupon and conducting mechanical tensile and bend tests.

Mandatory Adoption Protocol (QW-510 & QW-520)

Adoption is not an automatic rubber stamp. Prior to using an SWPS in production, the organization must fulfill the following mandatory steps:

1. Demonstration Test Coupon (QW-510): The organization must weld a demonstration test coupon following all parameters of the SWPS under its own direct operational control.
2. Examination Requirements (QW-510): The demonstration coupon must be visually examined per QW-144 and evaluated by either:
   • Guided bend tests per QW-160 (minimum number and type matching Table QW-451.1), OR
   • Full volumetric examination (radiography per QW-142 or ultrasonic testing per QW-143).
3. Form QW-485 Documentation: The organization must document the demonstration coupon welding parameters, inspection results, and adoption sign-off on Form QW-485 (or an equivalent corporate document).
4. Limitation on Variables: An adopted SWPS cannot be modified in any essential or supplementary essential variable. If an organization wishes to alter an essential variable, it must abandon the SWPS route and qualify a standard WPS via internal PQR testing under Article II.

7. Practical Piping Inspection Scenarios & Audit Findings

Scenario 1: Unqualified Single-Process Base Metal Extraction

A refinery contractor prepares a WPS for welding thin-wall 0.375-inch (9.5 mm) heavy-wall stainless pipe using GTAW only. The contractor cites PQR #77, which was welded on a 1.25-inch combination coupon consisting of 0.125 in. of GTAW root and 1.125 in. of SAW fill. The welding engineer argues: "PQR #77 qualified base metal thickness from 3/16 in. to 2.50 in. per Table QW-451.1, so our 0.375-inch pipe is well within range."

• Audit Finding: Violation of QW-200.4(b). When GTAW is extracted as a single process from a combination coupon, its qualified base metal thickness is limited to $2t_{\text{GTAW}} = 2 \times 0.125 = 0.250$ inches. To weld 0.375-inch pipe using GTAW alone, the contractor must have a PQR where GTAW deposited at least $0.375 / 2 = 0.1875$ inches of weld metal.

Scenario 2: Unapproved SWPS Implementation

A mechanical contractor on an ASME B31.1 high-pressure steam boiler line implements AWS SWPS B2.1-1-016 (SMAW of carbon steel). When the Authorized Inspector (AI) requests the procedure documentation, the contractor provides the purchased AWS specification booklet. When the AI asks for Form QW-485 and the demonstration test coupon records, the contractor responds: "Because this is a prequalified standard AWS procedure approved in Appendix E, we do not need to weld any test coupons."

• Audit Finding: Violation of QW-510. Mandatory Appendix E permits adoption of AWS SWPSs only after the specific organization demonstrates organizational capability by welding a demonstration test coupon, performing visual examination and either bend tests or volumetric NDE, and documenting the results on Form QW-485 prior to production welding.