Green Energy Transition: Carbon Capture & Hydrogen

A: A sounds right if you assume every loop must share a number, but API RP 14C doesn’t mandate tag numbering discipline that tightly. C borrows an ISA convention from packaged skids, where valve-centric numbering is common, yet that’s not universal and often breaks down in brownfield integrations. D is a real offshore problem, but treating live drawings as placeholders during PTW is how isolation errors happen. B aligns with how many electrolyzer vendors separate basic control from safeguarding or inventory protection, leading to different tag series even though the signal path looks similar on the P&ID.

A: A feels familiar because 3 mm shows up everywhere, but ASME VIII leaves corrosion allowance to the designer. B mixes up high-temperature hydrogen attack logic with wet CO2 amine corrosion. D sounds offshore-specific, yet ISO 15649 focuses on piping stress, not internal corrosion margins. C reflects how amine systems actually behave: degradation products, heat-stable salts, and reclaiming strategy dominate metal loss rates, with NACE steering metallurgy rather than a fixed allowance.

A: A works onshore, but offshore motion kills drainage in mesh pads and KOH fouling builds fast. C is attractive for low DP, yet cyclonic devices struggle with fine mist once velocity drops at turndown. D trusts vendor guarantees that don’t account for degraded operation or upset start-ups. B accepts the DP penalty, but vane packs drain more reliably under motion and tolerate a wider operating envelope.

A: A underestimates because assuming isothermal without intercooling isn’t defensible. C is a classic spreadsheet trap: the magnitude jumps when units are mishandled. D would only work if staging and intercoolers were explicitly defined, which they aren’t. B lands where adiabatic theory and real compressor efficiency usually put a CO2 service of this size.