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@georgeverghese In response to your last comment c, it seems they should had stayed at the original design pressure of 40 psig since cleary it reached 15 psig quite often. This is just speculation but it seems they "derated" the vessel to 15 psig in order to get out of doing the API 510...

Hi all, A client of mine has two ASME VIII stamped pressure vessels made by different companies in the 60s. Both are made of SA-7 and what puzzles me is the Tensile Strength on each vessel is 55k but the code says there is a 0.92 quality factor thus giving an allowable stress of 12,650 psig...

579 doesn't draw a clear distinction between general(part 4) and local corrosion (part 5) Any guidance on how I can determine which part (4 or 5) to use depending on the situation? thank you

@Ariba01123 Thank you for sharing that reference. Do you know the difference between sigma 1 and sigma 2 is in the photo? Interesting that above 1.42 for a/b, the hoop stress becomes compressive near the knuckle and crown region (and above 2 the compressive is greater than the tensile stresses).

Thanks everyone for the responses! MJCronin, my reference is ASME VIII Div. 1. They give different k factors for ellipsoidal heads. A 2:1 has a k factor of 1. Also, why does Pharma use that 80-10 head?

@sahsanb "Root cause of Stress Relaxation Cracking was identified to be non-compliance to WPS (high heat input) at the time of original construction ( i.e. year 2010)" Did the damage mechanism start shortly after the equipment was installed?

I only seen the standard 2:1 ellipsoidal head used on vessels and I'm curious if anyone seen any other ratio used before. If so, what was the reason why that particular ratio was used and not 2:1?

@DriveMeNuts "For ASME materials, the guaranteed minimum Yield and UTS of a material which is mandatory in design calcs, corresponds to plate which is ~100mm thick. However, 20mm plate has material properties superior to 100mm plate, and therefore there is waste material in 20mm thick vessels...

Is this for piping, vessel, tank? If so those ASME codes associated with those equipment have criteria regarding impact testing.

That makes sense. thanks Do you know where i can find an SOP for an industrial refrigeration process? I found documents online that describe the system but I really want to learn more about the controls and how engineers change the various process variables.

@Edstainless What are the name of these exchangers? Haven't heard of them but sounds neat!

I don't have experience with it but I heard from some air cooler vendors that they are hard to maintain and the pitches don't always match the set points. Any consideration in using VFDs to control air flow? Those are pretty standard.

Thank you for the response. So hypothetically, what would happen if the outlet pressure from stage 2 is pushed based the vapor pressure? Would the vapor simply condense? Would the outlet temperature from the condenser simply increase to match the new discharge pressure? I imagine it's hard to...

"You can also increase throughput if there is some extra cooling capacity at the stage 2D fin fan condensor, since this will in turn result in less flash gas generation at the economiser flash tank which floats on stage 2S." But the 2nd stage discharge pressure would still be limited by...

@TugBoatEng "The Mo in 316 is primarily added for chloride resistance. Your fluid has very little chloride so I see no benefits to running 316." I don't believe that is true. I read studies that 316 still offers better corrosion protection for non-chloride containing environments compared to...

I read each comment in this post. Thank you everyone this was super helpful

I'm working with a client that is dealing with high erosion rates due to sand in the well. I'm brainstorming some piping changes that can be made to decrease to erosion rates. Here they are: -Avoid 90 elbows and rely on 45 elbows -Size piping to have a flow velocity less than 10 m/s -Avoid...

Why were there two separate codes back then? How did one know which one to use back then? From what I read, if a vessel was built to API-ASME it didn't have a U stamp correct?

@weldstan True and rightfully so due to the technology back then However, the S.F. was increased to 4 temporarily due to WWII in the early 40s to save metal for the military. Is it safe to assume that any vessel built during this time period should be heavily questioned if they are still in...

@Christine74 Thank you for the guidance. Do you know why the joint efficiencies were relatively high in the 40s but were lowered starting in the 50s? I find that concerning because many of these old vessels were built with very little corrosion allowance so if today's joint efficiencies were...