1. Q: What is the significance of the "H" suffix in grades like TP446H?
A: The "H" suffix indicates a grade with requirements for elevated temperature yield strength. These grades have stricter carbon content limits to ensure creep resistance.
2. Q: What is the permissible weld repair depth on the finished tube?
A: Weld repair is generally not permitted on the finished tube without prior approval of the purchaser. The specification focuses on the quality of the as-manufactured product.
3. Q: What chemical element is critical for corrosion resistance in Grade TP446?
A: Chromium (Cr). TP446 has a high chromium content (23.0 - 27.0%) which provides excellent resistance to oxidation and corrosion.
4. Q: What is a major fabrication concern when welding ferritic stainless steels like TP430?
A: Excessive grain growth in the heat-affected zone (HAZ) can lead to embrittlement and reduced toughness. Controlled heat input and post-weld annealing are often critical.
5. Q: Do A268/A268M tubes require product analysis from the manufacturer?
A: The specification requires chemical analysis (heat analysis) from the steel producer. Product analysis may be performed by the purchaser, with tolerances defined in the specification.
