# Tag Info

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One of the mechanism that affect corrosion is known in the literature as Stress Corrosion Cracking (SCC). The idea is that tensile stressed regions are prone to crack development. Crack development essentially maximizes the area that corrosion can develop. Since corrosion, degrades the properties of the material, this accelerates further the crack ...

9

It depends on flue gas temperature. High temperature $(>250\ \textrm{C})$: use galvanized steel. Low temperature $(<250\ \textrm{C})$, use stainless steel or PVC as appropriate. See below for an explanation. Flues conveying higher temperature flue gas are typically made from galvanized, rolled, plain steel, as sulfuric acid condensation doesn't ...

8

Aluminum and steel are very near to each other in the Galvanic Series for seawater. So even if your apparatus is exposed to a corrosive environment along those lines, it should not corrode very quickly. The aluminum will corrode first, if corrosion occurs. If the exposed surface area of the steel is small compared to that of the aluminum, the corrosion that ...

7

In a situation where the environment does not allow the patina to form, does weathering steel perform any differently than carbon steel? Weathering steel is specifically designed to form a protective coating (i.e., patina) of rust that prevents the material underneath from corroding. Referring to the Wikipedia article (1) on the topic, Using weathering ...

7

Very probably, no. Galvanic corrosion required the existence of a reactive and conductive medium, which you don't have. If there is some (for example, at least moist air, or similar) best you can do to paint both of the metals, if you can. Generally, if none of the materials would corrode in an environment, galvanic corrosion is a non-issue (in that ...

7

If you are really considering catastrophic failure, what you are asking actually has several parts. The first is the coatings aspect, the second is the metal structure, the third is the connections, the fourth is the cables, the fifth would be the substructure and the sixth is the foundation. A failure of any one of these systems (with the exception of ...

6

The goal of using protective coating/paint is to reduce corrosion of the metal framework. The degree of corrosion varies from the top to sea level and depends on several parameters such as salinity of rain/ocean, humidity, avg. temperature, the acidity of rain, so on so forth. The principle behind protective coatings may differ in terms of layers, but ...

5

Safety issues in a "natatorium" (swimming pool) environment include the following: 1) Chlorine and other high acid gases that can corrode the steel. Both galvanization and paints/coatings can help, until the weather wears the protection away. 2) Water freezing and thawing. Basically, you need to keep water away from the pool at times when in it is likely ...

5

" Something different". Impressed current, very likely using titanium anodes , and the hulls have coatings/paint to reduce necessary current flow. Navy vessels can be relatively fast , so the turbulence of dozens of aluminium anodes on the hulls is unacceptable.On the other hand something like an oil platform where turbulence is not a factor hang ...

4

I believe what you are suggesting is impressed current corrosion protection. It is used commonly in pipeline and underground storage tank applications. Example ICCP is superior to sacrificial anode protection but is an active process while the latter is passive. If you do not coat the substrate I would think it would be corroding at a fairly steady ...

4

Wikipedia defines galvanic corrosion as: "Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially to another when both metals are in electrical contact, in the presence of an electrolyte. This same galvanic reaction is exploited in primary batteries to generate an electrical voltage." I don't see any electrolytes in ...

3

Corrosion can usually, but not always, be modeled as a 0-th order reaction which means linear with time. ASME B31 piping code treads lightly into this, mainly discussing factors to be used when specifying a corrosion allowance, and no more. However, we really just need a rate of reaction and some basic principals, and we can derive whatever we want! ...

3

The presence of a swimming pool in a natatorium causes a few unique issues that most buildings do not experience: High humidity levels - Water is everywhere and is frequently sprayed. Most buildings have ventilation systems that keep the humidity low. High chloride content - Chlorine is used for a disinfectant. Chlorine will rapidly cause corrosion on bare ...

3

Most stainless steels contain nickel around 10%. It is combined normally with chrome and molybdenum. The main problem, that a natatorium (i.e. swimming pool) is a highly corrosive environment, and most "stainless" steel alloy is a little bit, slowly, corroding here: Even aluminium gets a greyish-white surface layer. In the case of constructive materials, ...

3

There isn't necessarily a distance limit. Basically you are preventing galvanic corrosion via use of zinc which has a higher electric potential than the metals you are trying to protect. The corrosion occurs because you have two dissimilar metals (different potentials) in the precense of an electrolye (similar to a galvanic cell or battery). The electrolytic ...

3

There are two options: a passive method and an active method. The Passive method is to use a sacrificial zinc anode. The zinc corrodes instead of the metal that it is attached to. More information about the mechanics of the system can be found on the Wikipedia page. The Active method sounds more like what you are asking for in your question. This method ...

3

Just to add some unique engineering solutions that are used, depending upon applications: Brick works wonders - it resists the acid in the smoke well and can withstand the heat. Not metal, but well worth it if the application is right. For power plants, typical material use is acid brick lined steel. For industry, such as fume exhaust of potential ...

3

I wouldn't try for my kitchenware. I would strongly advice against it. The main problem is that you'd be in danger of digesting high temperature paint. Even though some of them might be inert, we'd all be better without them in our system. In order for this to work you'd need to make sure the following things (which are near impossible if you are not - or ...

3

In the real world ,I don't believe I have seen CORROSION at STRESSED areas. Corrosion may be accelerated at STRAINED areas; the strains introduce energy to the microstructure which may promote corrosion. Cracking is another story - which you did not ask about . Hydrogen cracking of high strength steels is likely the most common case . It can often occur with ...

3

The anodes may develop fouling but they still work. Most often they are aluminum , possibly alloyed ( eg. Galvalum ). The protected steel builds up a "calcareous" protective surface layer with time and then need less amperage. Anodes may also be replaced if necessary. Strong current flow ( tides ), especially with silt may clean off the calcareous ...

2

what is the most appropriate metal material i should use to avoid excessive corrosion in the exhaust pipe of the stove? If you're looking for corrosion protection, stainless steel is hard to beat. However, its corrosion resistance comes at a price. You will likely find that a stainless exhaust pipe will be MUCH more expensive than a regular mild steel ...

2

Following Paper gives Corrosion rate for 304 SS in Ammonia + Water Vapor environment:- Louis Caruso, Harold Mitchels,"Resistance of copper-nickel alloys to ammonia corrosion in simulated steam condenser environments" in Proceedings of American Power, vol. 4, 1980, pp. 319-323. Although this literature does not consider corrosion at high temperature. ...

2

I would say Thibd's answer excellent. However, one should look at the cost (including fabrication) on Monel, Incoloy 825, any Inconel or Hastelloy or Titanium . Although not "steel" they are metals that would answer the intent of the question. Also in "deep" water, corrosion of even carbon steel is not a problem because of low oxygen; but I think testing ...

2

It always depends on the concentration and where you place the copper within the human body. In my opinion, the most interesting example are implants which are coated with copper and implanted within the human body. The idea behind this is, that copper is toxic at very low concentrations for bacteria, and the toxic concentration for human cells is slightly ...

2

I'd say the mistake is assuming infinite stiffness for concrete and steel so only the rust has a strain. In reality, rust is probably the stiffest material involved, and you will get a better approximation by assuming infinite stiffness for rust and steel and calculating the strain and stress in concrete.

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It depends on how long you want it to last to decide if it is "proper". Generally the solution sounds like seawater ( although seawater pH is around 8 +).Corrosion will be strongly affected by factors not presented: oxygen, velocity, temperature, etc.As a wild guess a corrosion rate of one millimeter per year is possible.

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Two forms of Cathodic Protection: Sacrificial anodes; and ICCP (Impressed Current Cathodic Protection). Sacrificial anodes are passive and the anodes get eaten away as they protect the vessel. Aluminum anodes offer 3.4x the protection over zinc anodes, which means less are required but they cost more. Areas like rudder, propellors and thrusters, where ...

2

When ships are in static storage for extended periods of time, impressed current is used to protect them from corrosion. The counter electrode is a carbon rod the size of a telephone pole and the power supply occupies a small building all by itself on land nearby. The rods are immersed in the spaces between the "mothballed" ships.

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