what is the percentage of the plugging tube on the heat exachanger according codes or standard?

Answer 1

Please read the following and judge yourself.
You can not go by code every time as far as tube plugging is concerned.

*What are the allowable pressure drops and velocities in the exchanger?
Pressure drops are very important in exchanger design (especially for gases). As the pressure drops, so does viscosity and the fluids ability to transfer heat. Therefore, the pressure drop and velocities must be limited. The velocity is directly proportional to the heat transfer coefficient which is motivation to keep it high, while erosion and material limits are motivation to keep the velocity low. Typical liquid velocities are 1-3 m/s (3-10 ft/s). Typical gas velocities are 15-30 m/s (50-100 ft/s). Typical pressure drops are 30-60 kPa (5-8 psi) on the tubeside and 20-30 kPa (3-5 psi) on the shellside.
Suppose , you are using 4-pass exchanger and plugging all the tubes in one pass that is less than half! What will happen?
Now-a-days, most of the company run their plant on full capacity-so how can you afford plugging of even a single tube?

Answer 2

This is a site specific situation. Certainly there must be enough active tubes to permit the process to continue.

Another deciding factor is the increase in cost that will result as the number of active tubes decreases.

And akin to that, what are the costs of continuing to use the heat exchanger as is, compared with the costs of shutting down and re tubing the heat exchanger.

Lack of knowledge of these keeps us from answering the question with any degree of accuracy.

Answer 3

50