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  1. V

    Material used for the rotating shaft in Flowserve BB2 centrifugal pumps?

    Of course, it depends on the application. However, if you're simply looking for a material grade to perform calculations for your homework, you can refer to ASTM specifications for bars. For example, A276-31803 is a common choice for shafts in duplex stainless steel classes. Some manufacturers...
  2. V

    Temper Embrittlement(TE) 2.25 Cr 1 Mo steel P22/F22

    I have not yet conducted such an evaluation. However, as outlined in the EPRI document "Embrittlement of Power Plant Steels" (publicly available on the EPRI website), you can estimate the FATT using predictive formulas based on the part’s chemical composition. Additionally, metallography and...
  3. V

    Deaerator Usage In Power Plants

    To my knowledge, using chemicals such as hydrazine and creating a reducing environment will worsen the issue of single-phase FAC in HRSGs.
  4. V

    Deaerator Usage In Power Plants

    As a corrosion engineer, here are my points: In HRSGs, three primary chemical treatments are used. Additionally, solid alkalizing agents like trisodium phosphate may be added to HRSG water to enhance impurity tolerance and mitigate corrosion risks: AVT(R) (All-Volatile Treatment – Reducing)...
  5. V

    Chloride criteria in MR0175/ISO 15156-3 for austenitic stainless steels

    Even if we use SS316 in these conditions, crevice corrosion probably remains a concern. I would expect it to occur even in flowing seawater, depending on the crevice geometry.
  6. V

    Chloride criteria in MR0175/ISO 15156-3 for austenitic stainless steels

    Thank you for your valuable insights. It’s truly heartwarming to see experienced engineers in this forum dedicating their time to educate others. I may have overlooked something in this discussion, so I’d appreciate some clarification. To my understanding, pitting corrosion is among the primary...
  7. V

    Chloride criteria in MR0175/ISO 15156-3 for austenitic stainless steels

    I have experience working with stainless steels in RO desalination plants, where I’ve observed severe pitting in cases where SS316 was exposed to seawater. In RO desalination, chlorine (not chloride) is removed by dosing SMBS (sodium metabisulfite), a reducing agent. However, excessive SMBS can...
  8. V

    Bolts and Nuts for High-Temperature Applications – Ambiguities in European Standards

    Thank you for sharing your thoughts. I believe material selection depends on the specific application, and austenitic stainless steels are not universally prohibited. For instance, some boiler manufacturers use them for components like connecting baffles in applications up to 650°C...
  9. V

    Chloride criteria in MR0175/ISO 15156-3 for austenitic stainless steels

    Thank you for your helpful insights. Here’s what I understand from your posts: In a reducing environment created by H₂S, significantly higher chloride concentrations are required for stress corrosion cracking (SCC) to occur. However, pitting or crevice corrosion can still develop at chloride...
  10. V

    Bolts and Nuts for High-Temperature Applications – Ambiguities in European Standards

    Thank you for your insightful response. As you noted, EN 10269 provides high-temperature properties for fasteners, but it lacks mechanical property data for grades 1.4301, 1.4401, 1.4404, and 1.4304 at temperatures above 550–600°C, While, ASME Section II, Part D (Table 3) includes this data for...
  11. V

    Bolts and Nuts for High-Temperature Applications – Ambiguities in European Standards

    Thank you for joining this discussion. To clarify my question: Why are austenitic stainless steels excluded from a standard intended to guide bolt selection for high-temperature applications? Additionally, high-temperature decision-making requires extensive data, typically compiled by...
  12. V

    Bolts and Nuts for High-Temperature Applications – Ambiguities in European Standards

    Hello, Austenitic stainless steel bolts and nuts can be used in high-temperature applications, and their maximum temperature limit is quite high in the ASME Sec II Part D standard. For example, B8 grade (SS304) is allowed up to 816°C (though some technical limitations, like relaxation...
  13. V

    Chloride criteria in MR0175/ISO 15156-3 for austenitic stainless steels

    It is known that Austenitic stainless steels (SS304,SS316,…) are prone to SCC in chloride bearing environments. The chloride is normally controlled within a certain limit to prevent stress corrosion cracking. In some cases, such as hydrotest, standards normally suggest 50 ppm chloride...
  14. V

    PE/PP in Concentrated Sulfuric Acid Service

    Thank you for the insight. My remaining practical question: When PE/PP is exposed to sulfuric acid, how do we answer "When will it fail?" Based on the provided table and typical data for polymeric materials, there is no clearly defined failure timeline for these applications.
  15. V

    PE/PP in Concentrated Sulfuric Acid Service

    According to the NACE SP0391 standard, polyethylene (PE) and polypropylene (PP) are prone to environmental cracking in concentrated sulfuric acid. The standard highlights that: “The likelihood of cracking increases with higher acid concentrations and temperature, and a careful review of the...
  16. V

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    Thank you for participating in this discussion. You're correct—the fatigue appears to have initiated at the keyway, which acted as a stress concentrator, and this explanation seems quite reasonable. I also agree with your observation about the final fracture area near the 9:00 position, as I...
  17. V

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    As I was initially impressed by the intergranular microstructure and shiny appearance of the fracture, I overlooked the presence of beach marks, and my interpretation was biased toward a brittle fracture mechanism. Fractography requires a trained eye and an unbiased review of the entire story...
  18. V

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    Thank you for participating in this thread. I assume this is the most probable scenario. I was unable to observe any striations in the SEM images. Could you please elaborate on your observation? Are you referring to the lines with the darker background in the photo (Broken Shaft.jpg) that...
  19. V

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    Thank you for the comment. When examined under light and tilted, the fracture surface exhibits a sparkling effect. This characteristic appears uncommon for fatigue-induced failures, as such fractures occasionally display such reflective properties. Additionally, the intergranular morphology of...
  20. V

    Determining the Fracture Mode: Brittle Fracture vs. Fatigue in a Pump Shaft

    Thank you for participating in this thread. Similar grade in ASTM would be ASTM A276-420. The heat treatment was QT800 (950 0C -1050 0C quenched by forced air and tempered at 650-750 0C) and was tested according to ASTM A388-11.

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