ASME Section IX QB Brazing: Part QB Brazing Qualification Explained

What Is ASME Section IX Part QB?

Part QB is the section of ASME BPVC Section IX that sets the rules for qualifying brazing procedures, brazers and brazing operators for construction under referencing codes.

Brazing is a joining process in which a filler metal that melts above 450 °C (840 °F), but below the melting range of the base metals, flows into a close-fitting joint by capillary action. The base metals do not melt. That single difference is why brazing needs its own qualification rules instead of reusing the welding rules.

ASME Section IX, titled Welding, Brazing, and Fusing Qualifications, is a qualification standard and not a construction code. It becomes mandatory only when a construction code such as ASME Section VIII Division 1 or ASME B31.3 invokes it. The manufacturer or contractor stays responsible for the brazing it performs and for the qualification tests behind it.

Where Does Part QB Sit Inside Section IX?

Section IX has four parts: Part QG (General Requirements), Part QW (Welding), Part QB (Brazing) and Part QF (Plastic Fusing). Part QB follows the same logic as welding: qualify the procedure first, then qualify the person who will use it. Part QB itself is split into four articles.

Suggested forms for the BPS, BPQR and brazer record sit in Nonmandatory Appendix B. Paragraph numbers can move between editions, so confirm each reference against the edition your contract names. More brazing and welding code guides are collected in the ASME Codes & Standards category.

Which Codes Require Part QB Brazing Qualification?

Any construction code that permits brazing and refers to Section IX makes Part QB mandatory for that work. The qualification requirement follows the referencing code, not the brazing process itself.

• ASME BPVC Section VIII Division 1: Part UB covers brazed vessels, including brazing materials, procedure and performance qualification, and inspection of brazed joints. Our ASME Section VIII Division 1 overview shows where Part UB fits.
• ASME B31.3 Process Piping: brazed piping joints refer qualification of procedures and brazers to Section IX Part QB.
• Contract specifications: a purchaser may name AWS B2.2 or ISO 13585 instead. These frameworks are not interchangeable with Part QB unless the contract allows it.

What Are the BPS, BPQR and BPQ Documents?

Part QB uses three documents: the Brazing Procedure Specification (BPS), the Brazing Procedure Qualification Record (BPQR) and the Brazer Performance Qualification (BPQ) record. The BPS is the instruction, and the other two are evidence.

The relationship mirrors welding. The difference between WPS, PQR and WPQ maps directly onto BPS, BPQR and BPQ. For the document workflow, the guide on preparing a WPS and PQR applies in principle, although brazing uses its own forms and variables.

How Do Brazing Variables Control Qualification?

Brazing variables are the conditions listed in Part QB whose change may require a new procedure qualification or a new brazer test. Each brazing process has its own variable tables, listed in Tables QB-252 through QB-257. They cover torch (TB), furnace (FB), induction (IB), resistance (RB) and dip (DB) brazing, among other methods.

Variables are classed as essential or nonessential. A change to an essential variable beyond the qualified range needs a new BPQR. A nonessential variable can be changed in the BPS without requalifying, although the BPS should be revised and kept current.

Base metals are grouped by P-Number, and brazing uses a numbering system separate from welding, starting around P-101. For the welding side of the system, see our P-Number, Group Number, F-Number and A-Number guide and the complete ASME P-Number table. Brazing filler metals are grouped by F-Number and classified under AWS A5.8/A5.8M, which ASME adopts as SFA-5.8 in Section II Part C. Brazing has no A-Number.

How Do You Qualify a Brazing Procedure Under Part QB?

Brazing procedure qualification follows eight steps, from confirming the governing edition to qualifying the brazers who will use the released BPS.

1. Confirm the governing edition. Identify the construction code, the Section IX edition and any contract specification that invokes Part QB before any testing starts.
2. Select the process and joint. Choose the brazing process and the joint type (butt, scarf, lap or rabbet) that production will use.
3. Draft the BPS. List base metals by P-Number, filler metal by F-Number and AWS A5.8 classification, flux or atmosphere, joint design, temperature, time and technique.
4. Prepare the test coupons. Clean, fit up and assemble coupons exactly as the BPS describes, using the production joint design.
5. Braze and record. Braze the coupons while the responsible person records the actual variables used on the BPQR form.
6. Cut and test specimens. Prepare the specimens and run the tension, bend, peel or section tests that QB-202 and QB-451 require for the joint type.
7. Evaluate the results. Compare each result with the acceptance criteria. If a specimen fails, follow the code retest rules or revise the BPS and braze new coupons.
8. Certify and release. Certify the BPQR, issue the BPS that cites it, and then qualify each brazer or operator on the BPS.

What Tests Does Part QB Require?

Part QB procedure qualification tests depend on joint type. Butt and scarf joints use tension and bend tests, lap joints use tension and peel tests, and rabbet joints use tension and section tests. Brazer performance coupons are examined by peel or section tests. Sectioning may replace peel testing where peel testing is impractical.

Figure 4: Brazed lap joint coupon prepared for peel and section examination under Part QB.

How Are the Test Methods Used?

• Tension test (QB-150 series): loads a specimen to failure to measure the strength of the brazed joint.
• Guided-bend test (QB-160 series): bends a specimen around a former to expose lack of fill or cracking. The principles match those in our guided bend testing guide.
• Peel test (QB-170 series): pulls a lap joint apart so the separated faces show how completely the filler flowed.
• Section test (QB-180 series): cuts across the joint so the cross-section shows filler penetration, voids and bonding.

The general method of preparing and reading specimens is covered in mechanical testing of welds and joints.

How Are Test Results Accepted?

For tension tests, the specimen strength must not be less than the minimum specified tensile strength of the base metal, using the weaker metal where two differ. Bend, peel and section specimens are judged against the code limits for open defects and filler flow. Verify the exact wording and limits in the edition that applies to your project.

Worked Example: How Is a Brazed Tension Specimen Checked?

A tension result is checked by dividing the failure load by the original cross-sectional area and comparing the stress with the base metal minimum. The inputs below are assumed for illustration: a butt-joint specimen of SA-106 Grade B carbon steel pipe (minimum specified tensile strength 415 MPa, 60 ksi), 25 mm wide and 6 mm thick, failing at 66.0 kN.

Passing the tension criterion does not complete the qualification. The bend, peel or section specimens for the joint type must also be accepted before the BPQR can be certified. Real specimen dimensions come from the test paragraphs of the applicable edition, not from this example.

How Is a Brazer Qualified and Kept Qualified?

A brazer or brazing operator is qualified by brazing a test coupon to a BPS and passing the examination Part QB requires. The result is recorded on a brazer performance qualification record, such as the suggested format QB-484. Performance tests use peel or section examination, as shown in Table 4.

The qualification applies only within the performance variables of the code, such as the brazing process, base metal, filler metal and joint design. Welder qualification works differently, as explained in our guide to welder performance qualification under Section IX.

Qualification does not last forever. It expires when the brazer stops using the process for the period the code states, and renewal rules apply under QB-322 and the related Part QG continuity provisions. Confirm in your edition whether continuity requirements have moved to Part QG, and keep dated production records for each brazer.

What Changed for Brazing in the 2025 Edition?

The 2025 edition of Section IX, published by ASME on 1 July 2025, revised several tables that brazing procedures depend on. The brazing P-Number groupings were restructured, with new groupings taking effect in the 2023 edition and further adjustments made in 2025.

• Table QB-421 was added.
• QB-402.2 was revised in its entirety.
• Table QW/QB-421.2 was revised, and the ferrous and nonferrous parts of Table QW/QB-422 were combined into one table.
• API 5L grades with the L designation were added alongside the existing X grades in Table QW/QB-422.

How Does Part QB Differ From Part QW?

Part QB covers brazing, where the filler metal flows into a joint without melting the base metals, while Part QW covers welding, where the base metals are fused. The structure is parallel, but documents, grouping tables, variables and tests differ.

For the process-level trade-offs, read brazing versus fusion welding principles. For the welding qualification structure, see Article II welding procedure qualification and the thickness qualification range for PQR and WPQ. Thickness range rules for brazing are different and are found in the QB-451 tables.

Quick Reference: Part QB Paragraph Finder

This paragraph finder lists where each Part QB requirement normally sits. Check each reference against your edition, because numbering can change.

What Are Common Mistakes With Part QB Qualification?

The most common Part QB mistakes come from treating brazing like welding or from ignoring the edition and contract. Inspectors usually find these problems at the records review, not at the bench.

Part QB has limits. It qualifies the procedure and the person, but it does not set joint design rules, allowable stresses or inspection scope. Those come from the construction code. Requirements depend on the code edition and contract specification applicable to your project.

Frequently Asked Questions

Key Terms

Brazing

A joining process in which filler metal melting above 450 °C (840 °F) flows into a joint by capillary action without melting the base metals.

Brazing Procedure Specification (BPS)

The written document that lists the variables and ranges used to produce a brazed joint.

Brazing Procedure Qualification Record (BPQR)

The record of the actual variables used on a test coupon and the test results that support a BPS.

Brazer Performance Qualification (BPQ)

The record showing that a brazer or brazing operator passed the required performance test.

Essential variable

A variable whose change beyond the qualified range requires a new procedure qualification.

Capillary action

The force that draws molten filler metal into the narrow gap between close-fitting joint surfaces.

Joint clearance

The gap between the faying surfaces at brazing temperature, which controls how filler metal flows into the joint.

Peel test

A test that pulls a lap joint apart so the separated faces can be examined for filler coverage.

Conclusion

ASME Section IX QB brazing qualification comes down to two linked proofs: a qualified procedure and a qualified brazer. The BPS defines the process, the BPQR proves it on tested coupons, and each brazer then proves personal ability on a performance coupon.

Keep the variables, joint type, P-Numbers and filler F-Numbers consistent between the BPS and production, and always confirm the code edition in your contract. The 2025 edition changed several brazing tables, so older records deserve a second look.

As a next step, test your understanding with the ASME Section IX quiz with 150 questions, which includes a set on brazing and the 2025 changes.

Standards and References

• ASME BPVC Section IX, Welding, Brazing, and Fusing Qualifications, 2025 Edition, issued by ASME.
• ASME BPVC Section VIII Division 1, Rules for Construction of Pressure Vessels, Part UB, issued by ASME.
• ASME B31.3, Process Piping, issued by ASME.
• ASME BPVC Section II Part C, Specifications for Welding Rods, Electrodes, and Filler Metals (SFA-5.8), issued by ASME.
• AWS A5.8/A5.8M, Specification for Filler Metals for Brazing and Braze Welding, issued by the American Welding Society (AWS).
• AWS B2.2/B2.2M, Standard for Brazing Procedure and Performance Qualification, issued by AWS.
• ISO 13585, Brazing — Qualification test of brazers and brazing operators, issued by the International Organization for Standardization (ISO).
• ISO 17672, Brazing — Filler metals, issued by ISO.

About this guide. This guide was prepared by the WeldFabWorld technical team from the standards listed above. Verify every requirement against the code edition and specification applicable to your project.

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