Heat Exchanger Failure - Need Help

On no.1 I'd replace the tubes with the same material as the shell.

On no.2 I'd replace the gasket with something that is compatible.

On no.3. I'd fit the missing plate and get on to the cooling water chemicals supplier and have a bloody good moan.

Either that or I'd find another job somewhere else.

Did they tell you that you could go to an Engineering Forum, such as CR4, to get answers?

How would you evaluate and confirm that answers given to you by any member of this forum are accurate or reliable?

Perhaps you should get the equipment drawings and manuals out, along with the textbook containing the theoretical and mathematical information.

You must have re-edited after I saw your OP.

That would be real easy: Just see if they are a guru or not.

First, if CR4 did not exist, how would you go about defining the problem so someone with no technical background could understand it.

What steps would you than take to solve the problems thus identified?

It sounds like you have chemical compatibility and mechanical problems.

I'd perform an internet search for "how to find and solve heat exchanger failures", or "How to evaluate heat exchangers", "chemical compatibility problems in heat exchangers".

I assume they taught you how to use a search engine, since you found this forum.

1) - Cu pitting is unusual, possibly related to sour water (containing H₂S). Maintain a chlorine and/or bromine residual in the cooling water that will oxidize H₂S very quickly to sulfate. The alternative is to remove other conditions that introduce the H₂S into this water. On the other hand, gross over treatment with very high chlorine levels can damage copper tubes. Since the copper is far more noble than steel, usually the steel corrodes more due to the galvanic potential that exists. If there are particles in the water that may stick to the copper this is bad, since gouging of the metal on the downstream side may fail the tube and make it appear as though pitting is the culprit. Check for sulfate reducing bacteria in the water that can colonize and attack metals with acidic sour gas.

2) - You may have no alternative but switch gasket to Viton.

3) - If the cooling water source is not kept in the treatment range, there will be severe corrosion to CS, leading to immediate or near term failure. Put this cooler on a closed loop cooler, using water of controlled chemistry recommended by the manufacturer (i.e. reasonably low TDS, but controlled alkaline pH, hardness ions limited to the German degree specified). Other alternative for natural gas compressor after-cooler is to use a large fin-fan cooler that is air-cooled (effectively what I already told you, except cooling the gas directly with air), but it requires a hell of a lot larger cooler.

As a "Graduate Trainee Engineer" you have three tasks:

1. As a Graduate, use the knowledge that you gained in class to analyze the assignment.

2. As a Trainee, put that knowledge to work solving real life problems.

3. As an Engineer, show superior critical thinking skills that go beyond your current comfort zone.

Unfortunately if you can't/won't/don't do numbers 1 & 2 on your own, you'll never earn the right to get to number 3.

I am given an assignment to study

I don't believe we can really help you then since the task has been given to you and you are trying to outsource it to us.

It sounds like management want you to do this yourself and learn through the process of personal development. Getting others to do the hard work for you won't teach you anything.

Embrace this as the challenge it is supposed to be and go and do the research yourself. You will find that this is a very rewarding experience and you will grow as an Engineer. This is what Engineering in the real world is all about.

I work for a company that has made heat exchangers for over 40 years now. I know we have a lot of competitors in this industry. Most any heat exchanger manufacturer can certainly help you and direct you to get an exchanger that will be compatible with your requirements. I will not attempt to answer this, since I am a controls engineer for our process skids, not a heat exchanger designer.