Device For anticorrosion

I'm guessing it's this.

They could be insulators to prevent dissimilar metal contact. They could also be made of a metal that is halfway between the the piping and the heat exchanger materials on the electromotive spectrum to act as a buffer. But my guess would be insulators.

Two dissimilar metals will create a thermocouple junction, promoting corrosion.

I know a brass fitting between a copper and iron pipe will prevent excessive corrosion, but I did not find the rationale and have to go.

It is more important in a fresh water system than in a closed heating system where the ion supply is limited.

Di-electric flange kits or di-electric unions are used to help prevent corrosion from electrolisis

probably are pipe spool of insulating, non-conducting materials (plastic) or a metallic pipe internally lined with insulating, non-conducting materials to avoid the possibility of galvanic corrosion between the material of the incoming pipe and the materials of the exchangers.

try to look at the piping class and see if the materials of the pipes are carbon steel and the exchangers and alloy (Stainless steel of similar)

S.

Corrosion Control & Corrosion Protection

We used to protect the equipment designed and fabricated at our facilities (upon an owner request) by the common procedure for protection called Cathodic Protection. The system consists of a number of special Aluminium Anodes (or other proper material) with a defined size depends on the area to be protected. By using simple calculations, it is easy to estimate the size and number of anodes required to full protect the vessel.

The subject is completely different than cathodic protection.

I found a recommendation to change those sets of device of anticorrosion each two years...!!

Can this help to advise?

Sometimes, bacteria and organics formulated at witted surfaces of equipment (e.g. suction of submersible pumps, columns of dikes and platforms at sea water, ... etc.) , in this case we install such device to supply an electric current with a specified volt and ampere for killing the bacteria, and behave as antifoulant.

Another example of fields where we use antifouling systems is to protect the tubes of heat exchangers, where fouling due to formulation of moss alga and bacteria will accumulate inside the tubes and reduce the internal diameter which decreases its efficiencies.

Sometimes we use chemical injection inhibitors to be injected into the fluids going through the tubes of heat exchangers to kill the moss alga and bacteria. Otherwise we use special device to produce a such current capable to kill the moss alga and bacteria.

Also, and in addition to what mentioned previously, the moss alga and bacteria can cause corrosion to the interiors of tubes. So we have to use the proper procedure to protect our system and maintain its efficiency.

there is no electrical connection in the device for anticorrosion about which I am asking

If it isn't a problem, can you please send a copy of that P&ID? to allow close understanding and blueprint reading of that device.

My e-mail is: abujalala2005@yahoo.com

There would not be. A sacrificial anode utilizes the galvanic potential of the two dissimilar metals along with the water as the electrolyte to make it's own small battery.

You have to understand that corrosion is an electrochemical process, you need four things for corrosion to occur: You need an electrolyte (almost ALWAYS water), You need two dissimilar metals far enough apart on the electromotive scale to generate appreciable current (or two different areas of the same piece of metal with a different electromotive value due to inclusions or grain boundaries or whatever), And a physical electrical connection between the two metals. What a sacrificial anode does is to place a metal much more anodic than either of the other two metals into the system. Since it is ALWAYS the anode of the couple that corrodes away this protects the other two metals. So by supplying a metal anode that is more anodic than any of the other metals present, you protect the other metals while allowing the sacrificial anode to corrode away.

Insulators interrupt the corrosion process by a different mechanism. Instead of allowing a piece of metal to corrode, they electrically isolate the two metals so that electrons cannot flow between them, interrupting the electrical circuit. With no electron flow, no corrosion can take place.

http://www.corrosion-club.com/basictheory.htm

i think that the only solution to find out something about it is to look at your documentation and see if there is a reference to a specification, data sheet or something similar. usually on a p&id there is a number that identify a special piece or a device. if it's not there than who made the p&ids did a very bad job...

S.

corrosion control

Yes strider6, that exactly what I like to say, to avoid misunderstanding or spending a lot of time in a subject to recognize it with insufficient data.