The distinction between 321 and 347 stainless steel relies on detecting titanium and niobium content. Both grades are visually identical, and misidentification increases intergranular corrosion risk after welding. For example, using 321 instead of 347 in high-temperature piping (870°C vs 925°C limits) leads to reduced creep strength, weld decay, and possible rupture. Regulatory mandates require positive material identification of stabilized stainless steel; incorrect grade selection can trigger safety violations, asset downtime, warranty loss, and liability claims.
321 vs 347 stainless steel
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Importance for Fabricators, EPCs, and End-Users
PMI is mission-critical in fabrication, plant maintenance, and QA. Fabricators depend on stainless steel alloy composition verification methods. EPCs must confirm grade selection before welding for piping and tubing; missteps expose joints to weld decay, corrosion, and regulatory penalties. End-users verify stainless steel types in thermal process units, ensuring certified material in high-temperature, cyclic service.
XRF Alloy Grade Identification: Technology Overview
Introduction to X-ray Spectroscopic Analysis
X-ray fluorescence (XRF) excites atoms in solid stainless steel using a focused X-ray beam. Each element emits a unique X-ray spectrum, enabling rapid, precise identification of alloy composition. Major and trace elements are detected within seconds, supporting verification in real-time fabrication, welding, and asset management. Direct, non-destructive XRF analysis achieves sub-ppm detection of stabilizing elements, confirming alloy identity and compliance with fabrication guidelines and requirements.
Advantages of XRF for Stainless Steel Identification
XRF analysis is non-destructive, portable, and suitable for on-site PMI tasks. Lonnmeter XRF analyzers distinguish 321 and 347 using precise measurements of Ti (0.20–0.70%, 321) and Nb/Ta (0.30–1.10%, 347), verifying grades in piping, tubing, and welds. Field deployment eliminates costly rework due to material mix-ups, ensuring traceability and certification. XRF workflows allow seamless data integration with quality management systems.
Product Features of Lonnmeter XRF Alloy Analyzer
Technical Parameters and Features
Lonnmeter XRF analyzers deliver detection from magnesium (Z=12) to uranium (Z=92), providing full-range austenitic and stabilized stainless steel identification. The device rapidly distinguishes critical elements, resolving Ti (for 321) and Nb (for 347) at sub-0.1% mass content, supporting advanced stainless and superalloy discrimination. Speed: 30 seconds per sample.
Applications and Benefits for 321/347 Identification
Lonnmeter XRF enables rapid weld seam inspection, in-place verification for piping or pressure vessel fabrication, fast asset mix-up prevention, and reduced downtime. Fabricators use it to verify correct 321/347 deployment at incoming material, pre-weld, and post-weld stages. Immediate certification output eliminates costly rework due to grade errors, underpins plant asset management, and streamlines stainless steel grade change control processes across industrial sectors.
Ensuring Quality and Compliance with PMI Equipment
Accurate identification prevents mix-ups between stainless steel types, including 321 and 347, which is essential for fabrication and welding integrity. The analyzer supports compliance with ASME B31.3 and BPVC Section II, confirming grade traceability pre- and post-weld through rapid X-ray spectroscopic analysis for metal alloys.
Supporting Documentation and Certification
PMI data from Lonnmeter XRF integrates seamlessly with fabrication, welding, and supply chain recordkeeping. Every measurement links to project requirements and material specifications, forming tamper-proof documentation for audits and certifications. The system logs PMI results with timestamps for traceability, supporting customer audits and regulatory verification under AWS D10.4M/D10.4. Certification workflows benefit from direct grade reporting for stainless steel alloy composition verification methods, enabling real-time inventory updates and forging a consistent chain of custody. This ensures validation of stabilized stainless steel advantages and applications, particularly for distinguishing between stainless steel grades 321 and 347, and supports compliance during fabrication and asset management.
To request a quote for a Lonnmeter XRF Alloy Analyzer, complete the contact form or use the direct technical consultation line. Indicate your primary use case, such as austenitic stainless steel properties and uses, or stainless steel alloy composition verification methods. Detail the specific stainless steel types—especially if comparing 321 vs 347, stabilized stainless steel advantages, or conducting positive material identification (PMI) for stainless steel grade testing and certification methods.
FAQs
Why is alloy composition verification critical for stainless steel fabrication?
Traceability and compliance demand documented chemical composition. PMI prevents catastrophic failures due to alloy mix-ups. Welding pipes and tubes with the wrong grade risks intergranular corrosion and mechanical malfunction, especially under high-temperature conditions.
Can XRF analyzers identify other stainless steel grades?
Yes, Lonnmeter XRF analyzes stabilized (321, 347), duplex, super-austenitic, martensitic, and precipitation-hardened stainless types. All major alloy groups are confirmed within seconds except those containing only light elements. Partial grade chart for 300-series below.
Post time: Feb-26-2026
