Can all A307A material be certified to Grade 2?
Answer
No, not all A307A material can be certified to Grade 2.
Size and Configuration Limitations
The Grade 2 specification has different mechanical requirements depending on the diameter, length, and type of fastener.
- Grade 2 requirements for sizes 1/4 through 3/4 in. apply only to bolts and screws 6 in. and shorter in length, and to studs of all lengths. For bolts and screws longer than 6 in., Grade 1 requirements shall apply
A307 Grade A fasteners
| Grade Marking | Specification | Material and Treatment | Nominal Size (in.) | Mechanical Properties | Hardness Rockwell | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Proof Load Min (ksi) | Yield Strength Min (ksi) | Tensile Strength Min (ksi) | Elong % Min | RA % Min | Min | Max | ||||
| PB | SAE J429 Grade 1 | Low or Medium Carbon Steel | 1/4" – 1 1/2" | 33 | 36 | 60 | 18 | 35 | B70 | B100 |
| PB 307A | A307 Grade A | Low or Medium Carbon Steel | 1/4" – 4" | – | – | 60 | 18 | – | B69 | B100 |
| PB | SAE J429 Grade 2 | Low or Medium Carbon Steel | 1/4" – 3/4" | 55 | 57 | 74 | 18 | 35 | B80 | B100 |
| PB | SAE J429 Grade 2 | Low or Medium Carbon Steel | 7/8" – 1 1/2" | 33 | 36 | 60 | 18 | 35 | B70 | B100 |
Proof Load Requirement
Grade 2 fasteners must successfully pass a proof load test, confirming that the fastener can withstand a specified load without experiencing permanent deformation.
This test ensures performance consistency and safety in applications where the fastener’s structural integrity is critical. By comparison, A307 Grade A does not have a proof load requirement. Therefore, if this value is not included in the certification documents, they cannot be certified to Grade 2 without additional testing.
Minimum Yield Strength Requirement
Grade 2 requirements for ¾” and smaller headed bolts 6” in length and shorter, and all lengths of studs (fully threaded rods) have a significantly higher minimum tensile strength requirement than A307 Grade A fasteners. Therefore, A307 Grade A fasteners in these configurations will not cross-certify to Grade 2. Even if they exceed the tensile-strength requirements of Grade 2, the proof load and/or yield strengths of those fasteners (when reported) may not be high enough to meet Grade 2 requirements.
Portland Bolt Expertise
When it comes to understanding fastener specifications, Portland Bolt stands out as a trusted industry expert. Our knowledgeable team works with ASTM and SAE standards every day, ensuring your products meet the exact specifications required for your project.
Whether you’re sourcing structural bolts, OEM components, or custom-manufactured fasteners, Portland Bolt’s sales representatives provide the technical guidance and quality assurance you need to make confident purchasing decisions.
With over a century of manufacturing experience, we make sure you get the right product, made right — every time.
Additional Resources
For more technical information, visit these helpful Portland Bolt reference pages:
- SAE J429 Specification Overview – Covers mechanical and dimensional standards for Grades 1, 2, 5, and 8 fasteners.
- Strength Requirements by Grade – Detailed mechanical properties and dimensional limitations for various bolt grades.
- ASTM A307 Specification Overview – Summarizes the A307 Grade A and B requirements and allowable applications.
