Pitfall #3: Material Non-Compliance – Avoiding Wrong Specs and Brittle Fracture
5 Common Pitfalls in ASME B31.3 Process Piping Compliance
0.0 Introduction
0.1 Pitfall #3: Material Non-Compliance – Avoiding Wrong Specs and Brittle Fracture
Selecting the right material is not just about choosing ‘stainless’ or ‘carbon steel.’ In ASME B31.3 compliance, the material must be suitable for the fluid service, temperature, and pressure. Pitfall #3 is the failure to account for metallurgical limitations, particularly Brittle Fracture in low-temperature services.
1.0 Material Selection & The Impact of Metallurgy (H2)
1.1 Listed vs. Unlisted Materials (H3)
‘Listed materials’ are those specifically identified in the Code’s tables. An ‘Unlisted material’ can be used, but it requires the Designer to verify properties and determine allowable stress. Many engineers fall into the pitfall of using unlisted materials without this mandatory justification.
1.2 Low-Temperature Service & Impact Testing (H3)
The Code uses ‘Impact Test Exemption Curves’ to determine if testing is mandatory. If your design temperature falls below the curve, testing is mandatory. For high-temperatures, one must refer to Materials and Design for High Temperatures.
2.0 Procurement Excellence (H2)
2.1 Ensuring Proper MTRs and Traceability (H3)
Compliance continues through the supply chain. A Material Test Report (MTR) must prove that the steel delivered matches the design specification. In Piping Construction, the lack of traceability is a leading cause of safety shutdowns.
Recommended Training Courses
FAQ Section
- What is a Material Test Report (MTR)? An MTR certifies that the material meets specific ASTM or ASME standards.
- When is impact testing mandatory? When the design minimum temperature is below the exemption temperature provided in Figure 323.2.2A.
- Can I use unlisted materials? Yes, but only with documented engineering justification according to B31.3 rules.
