1. Q: What does API 5L PSL2 mean and how is it different from PSL1?
A: API 5L specifies requirements for line pipe. PSL2 (Product Specification Level 2) has more stringent requirements than PSL1. This includes mandatory impact testing, maximum limits for carbon equivalent (CE) , and tighter limits on mechanical properties. PSL2 is typically required for critical offshore, sour service, or high-pressure gas lines -8.
2. Q: For what applications are welded pipes made of UNS N08926 specified?
A: UNS N08926 is a super-austenitic stainless steel with excellent resistance to pitting and crevice corrosion in seawater and other aggressive chloride environments. Welded pipes in this grade, often per ASTM B804, are used in offshore platforms, desalination plants, flue gas desulfurization (FGD) scrubbers, and marine exhaust systems -4.
3. Q: What is the significance of the "H" grade in stainless steels like 321H or 347H?
A: The "H" designation indicates a higher carbon content (0.04-0.10%) within the grade specification. This higher carbon provides greater high-temperature strength and creep resistance, making these grades suitable for elevated temperature service, such as in boilers, superheaters, and refinery heaters -7.
4. Q: What is a "sour service" condition and what pipe requirements does it impose?
A: Sour service refers to environments containing wet hydrogen sulfide (H₂S) , which can cause sulfide stress cracking (SSC) and hydrogen-induced cracking (HIC). Pipes for sour service require strict control of steel chemistry (low sulfur, inclusion shape control), hardness limits (e.g., maximum 22 HRC), and specific testing per standards like NACE MR0175/ISO 15156.
5. Q: What is a "decorative" welded stainless steel pipe, and how does its standard differ?
A: Decorative pipes, like those meeting JG/T 3030 or GB/T 18705, are used for aesthetic applications such as handrails, furniture, and architectural trim. The standards focus more on surface finish, straightness, and appearance rather than internal pressure integrity or high-temperature properties -3.
