7 replies to this topic

[BryanO]

Hi,

 

What consideration should take into account before ones decide to clean up the copper pipe? I have a pipelines, and found that roughness is about 6.7e-6 m. The literature stated that the roughness of clean copper pipe is about 1.5e-6, which is far less than the roughness of the pipelines I investigated. Should that mean the copper pipe should be cleaned.

 

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[fallah]

 

Bryan,

 

What is the method by which you have measured the pipeline roughness?
 

[Art Montemayor]

Bryan:

 

Fallah has gone to the heart of the matter.  I too am interested in how the rugosity measurement was obtained for the copper pipe in question.

I also would add the following additional questions:

• What is the specific literature source that indicated the rugosity of copper pipe as 1.5 x 10^-6
• How long is the copper pipe?
• What is the fluid transported in the copper pipe?
• What do you mean by "cleaning" the copper pipe's rugosity?  Cleaning does not resolve the metal's surface roughness.  Cleaning can only remove any surface contaminants that may be clinging to the internal wall and can possibly be dissolved or washed off.  Is that what you are describing?

[BryanO]

Fallah:

 

The method I used is by calculating h_measured and h_predicted. h_measured is based on the Bernoulli equation assuming all pipe diameter is the same. h_predicted account for the minor and major losses in the pipe system. Roughness is estimated by minimizing the sum of the squared error between the measured head loss and the predicted head loss, with roughness the only parameter.

[BryanO]

Hi Mr. Montemayor:

 

Thanks for your reply:

 

1. The literature is chemical engineering reference manual for the PE Exam.
2. The long of the pipe I investigated is about 17 m
3. The fluid transported in the pipe is water
4. Yes, what I mean by cleaning is  removing any surface contaminants that may be clinging to the internal wall and can possibly be dissolved or washed off. 

My questions is "Is that to safe to say that copper pipe should be cleaned only by seeing the roughness as the parameter?"

What I think is, if the roughness increases to certain limit, possibly, there are any surface contaminants developed.
 

Edited by Art Montemayor, 03 April 2016 - 09:09 AM.

[fallah]

Bryan,

 

The method you used, if the roughness of clean copper pipe has been considered for predicting head loss, appears to be reasonable.

 

The main point is the roughness difference, regardless of its value, has been generated mostly due to corroded surface of pipe inside not the other factors such as fouling; then clean up operation might not lead to any improvement in roughness value. Let's have your viewpoint in this regard...
 

[BryanO]

Fallah,

 

Thank you for your insight.  I agree with you. However, is there any critical (extreme) value of roughness of Copper pipe so it is safe to say that it is corroded?  I look into many literature but could not find one.  What I mean is that the roughness can increase to certain degree due to additional layer developed on the surface, but not yet assumed as corroded pipe.  What do you think?

[fallah]

Bryan,

 

I don't think there would be a reference in which you can find any roughness value for corroded copper pipe. Indeed, I think additional corroded layer developed on the copper pipe surface is more effective in reducing the inside diameter of the pipe than to increase the roughness to certain degree.