Mechanical Testing Requirements for MIL-STD-3040A

What You Need To Know: Article 2 of 7 - Mechanical Testing Requirements

In our initial article about welding qualification under MIL-STD-3040A, we focused on the Procedure Qualification Record (PQR) and the necessary elements for both welding procedure and personnel certification. In this continuing series, we now look at the required mechanical testing and inspection that are part of both the PQR and WPQ (Welder Performance Qualification) records. 

We will pay particular attention to two elements that are often overlooked by military / defense fabricators: 

• Testing facility accreditation and inspection personnel qualification

• Key changes to mechanical testing requirements in the most recent revision of MIL-STD-3040A

1. Procedure Qualification Record (PQR)

To qualify a welding procedure under MIL-STD-3040A, a Procedure Qualification Record (PQR) must be developed. The PQR documents the welding variables and the results of mechanical testing conducted on a test weldment. The mechanical tests typically required include:

• Tensile Test: Assesses the ultimate tensile strength of the weld.

• Bend Test: Evaluates the ductility and soundness of the weld.

• Impact Test: Determines the toughness of the weld, especially at low temperatures.

• Hardness Test: Checks for hardness variations in the weld and heat-affected zone.

These testing requirements vary depending on the classification of the weld for its material type and severity of application. See Table VI below for more details on specific mechanical tests required for the various weld classifications.

2. Welder Qualification

In addition to qualifying the welding procedure, individual welders must also be qualified to ensure they can produce welds that meet the required standards. This involves performing a Welder Performance Qualification (WPQ), which includes:

• Welding a Test Coupon: Under specified conditions.

• Testing the Weld: Subjecting the weld to mechanical tests similar to those in the PQR.

• Documenting Results: Recording the results to ensure compliance with the specified standards.

The WPQ ensures that the welder has the necessary skills and knowledge to perform welds that meet the required standards. It is important to document and retain records for all PQR and WPQ mechanical tests for the entirety of the contract while the applicable PQR is in use.

3. Ongoing Production Qualification

For ongoing production, the welding procedure and welder qualifications must be maintained to ensure consistent quality. This involves:

• Regular Monitoring: Conducting periodic inspections and tests to verify that the welding procedure and welders continue to meet the required standards.

• Requalification: Performing requalification tests if there are significant changes in materials, welding processes, or other variables that could affect weld quality.

• Documentation: Maintaining detailed records of all inspections, tests, and qualifications to demonstrate ongoing compliance.

By adhering to these mechanical testing requirements, organizations can ensure the production of high-quality, reliable welded components that meet the stringent requirements of MIL-STD-3040A.

4. Testing Facilities and Personnel: Qualification is Not Optional

Section 5.7 of MIL-STD-3040A emphasizes that mechanical testing must be conducted by qualified laboratories using certified personnel. This requirement is critical to ensure the accuracy, repeatability, and credibility of test results that underpin weld qualification.

5.7.1 Requirements: “All destructive testing shall be included in the PQR or WQR. Entities conducting destructive testing shall be ISO/IEC 17025 accredited, or have an internal quality document for destructive testing. The internal quality document shall include procedures for all equipment used for testing and calibration records, documenting appropriate equipment calibration prior to use and in accordance with the applicable testing standard." 

5.7.1.1 Destructive testing personnel qualification: "Entities that complete destructive testing internally shall develop a training plan for destructive testing personnel ... Entities that sub-contract destructive testing shall use ISO/IEC 17025 accredited test facilities."

This means that even organizations with in-house testing capabilities must ensure their labs are properly accredited and that their technicians have verifiable training and qualifications aligned with national and military standards.

5. What’s New: Charpy and Microhardness Testing Now Mandatory for Class III Welds

One of the most important changes in MIL-STD-3040A is the mandatory requirement for both Charpy V-notch and Microhardness testing on all Class III welds — the highest criticality level. Previously either Charpy V-notch or Microhardness testing were required, where both tests are now necessary.

See Table VI below to compare the February 14, 2024 revision to MIL-STD-3040A versus the previous March 24, 2022 version.

MIL-STD-3040A (14 February 2024 Revision)

M

These changes signal a heightened emphasis on mechanical performance validation and underscore the Department of Defense’s continued commitment to the structural integrity and reliability of welded components in mission-critical applications.

Bottom Line

Organizations seeking to qualify weld procedures under MIL-STD-3040A must:

• Partner with accredited and approved test laboratories like United Technical Inc.

• Ensure testing personnel meet all qualifications outlined in Section 5.7.

• Be aware that both Charpy V-notch and Microhardness tests are now required for Class III welds — even if prior qualifications did not mandate them.

Understanding and implementing these updated requirements is vital for maintaining compliance, ensuring performance, and avoiding costly rework or delays.

Rick Slade, VP of Operations