Will depend on the corrosion parameters as the a function of temperature. For instance if you are dealing with plain old open-to-atmosphere water than the corrosion rate increases with temperature and then drops off as the oxygen solubility decreases. This would cause your current requirement...
Check with a process engineer and understand the rich loading and if two phase flow is developing across the exchanger. It wouldn't be uncommon to develop two phase flow on the rich side of the exchanger as the amine is heating up and there is a typical pressure drop across the exchanger. The...
Your coating efficiency seems a bit low. Is this an older pipeline, designing for a degraded coating, portions not coated, company design standard? We find that most of our coatings (three layer system with corrosion barrier, insulation, outer protective layer) have efficiency >99%, but this...
In your case you would be likely placing your bed at "remote earth" to provide the current distribution to a long pipeline.
You will need to understand the soil resistivities to properly size the anode bed as well as a current test to determine the required current to achieve...
H2S charts for corrosion can be found in papers by Sardisco in NACE Corrosion in the 1960's and by Smith in 2001 NACE conference.
You can use these sources to cross-reference the other sources that are availible.
Since your paint is damaged, you must clean the pipe to a clean surface. Your inspection should be fairly easy as you are expecting external corrosion so you can visually inspect the line. Any noticable pits can be measured using a pit gauge. You can use UT to confirm the wall thickness, but...
We use welded plates in amine service. The set up is every other gasket is eliminated and replaced with a weld. In this arrangement we have the rich amine between two welded plates (a set) and hot lean amine between the sets of welded plates (contained with a gasket).
What we have is severe...
The biggest error we find in eddy current is due to the operator. We almost always stick with the same guy to do any of our eddy current or remote field eddy current.
Like aybee said above, make sure that you have a calibration tube.
316SS, as long as it meets NACE 0175, should be just fine for your application. We use C276, but we also are using high concentrations of chlorides and much higher levels of H2S and CO2.
The company you are designing for and local regulations may dictate your answer. I work in a plant that has pressure >5000kPa total pressure with over 30% H2S and nothing is considered in lethal service.
The only way to go from a relatively low hardness of annealed 304 to the high hardness that you see is if you go way beyond the yeild strength of the material. You can recheck the design calculations of the exchanger, but hopefully the exchanger was designed so stay well below the yield...
You could contact Dr. Wayman at the University of Alberta in Canada (mike.wayman@ualberta.ca) as he specializes in Archaeometallurgy and Historical Metallurgy if you need more help (from the replies to this posting I am not sure you do). He concentrates in various aspects of historical...
You will get a bunch of different answers to this questions as the mechanisms are not clear. One point I want to make is that although isolated pitting does occur, having an area of corrosion also occurs.
Typcially a wet H2S system is not overly corrosive due to the formation of the various...
I agree with PVRV that you need to verify the indications with digs. The company you are working for should have guidelines for determining when an indication is a potential candidate to verify.
If you are suspecting external than the procedure of excavation should include methods of...
Depending on the conditions, the assumption that the worst has past could be dangerous. I suggest you preform a fitness for service assessment (API 579 or a similiar process) using someone experienced in this type environmental cracking.
If you decide to operate this vessel you should...
What are the standard procedures used by others for hydrotesting new valves? For instance, if we were switching from a carbon steel to a stainless steel valve, we typically wouldn't hydrotest the valve and just put it in service. The problem here is that API 598 has shorter duration times on...
I don't have NACE MR0175 so maybe you can correct me but isn't UNS31803 limited to something like 1.5psi partial pressure H2S? I can't remember off the top of my head.
juang, this is another document that you may have to pay attention to NACE MR0175.
Are there some good industry courses on the design and operation of distillation towers? What I'm looking for is a two to five day course on the subject.
Thanks
Check some old NACE papers concerning the selection of materials for sour gas treating. There are at least 4 papers out there on this topic.
Most gas treating systems use carbon steel for the majority of the system and selectively use stainless for critical locations. We have had to replace...
