Does anibody know something about parasit currents or something like that in order to check possible pipe defects, as corrosion, erosion in water systems. I am not talking about eddy current, but other different methods to check pipes like charging them for example .....

Pleas, if you have some links to proffesional sites or equipment to do this tests, please refer it in this fórum.

Thanks,

Allen

Where do you get the term parasit currents then, if not from internet?

This message has been edited. Last edited by: Josh,

Is it something ike this?

ABSTRACT
This paper describes the development of an EMAT based PIG for in-line inspection of flaws in a 30 inch natural gas pipeline. The sensor is capable of detecting physical flaws (e.g., SCC, circumferential and axial flaws, and corrosion) in pipe walls of gas pipelines. Using an in-line non-contact ultrasonic sensor (EMAT) flaws are determined in the wall of the pipe that the current MFL technology has problems detecting. One EMAT is used as a transmitter, exciting an ultrasonic impulse into the pipe wall while a second EMAT located a few inches away from the first, is used as a receiving transducer. This paper reports on the identification of flaw signatures in the receiver output. Since the discrete wavelet transform of the signal will be non-shift invariant, its coefficients cannot be directly used as a pattern recognition feature. However, comparing composite properties of the signal on different scales is useful, because the mode conversion caused by a flaw changes the composite properties of the signal in wavelet space. For the EMAT data, the useful information projects onto five mutually orthogonal wavelet scales. This paper also presents the results of 3D modeling using BEM performed on a horizontal guided wave incident on a flaw.
http://www.ornl.gov/~webworks/cppr/y2001/pres/119096.pd...ng%20pipe%20defects'

I am referring to the possibility of pipes charged with residual energy from somewhere and conducting electricity to ground. Perhaps, this situation could increase the amount of oxidation material in pipes, motivating excesive corrosion for example.

In this hipotetical case , which would be the inspection method?

Regards,

Rubén Lorenzo

[QUOTE]Originally posted by allen_forum:
I am referring to the possibility of pipes charged with residual energy from somewhere and conducting electricity to ground. Perhaps, this situation could increase the amount of oxidation material in pipes, motivating excesive corrosion for example.

In this hipotetical case , which would be the inspection method?

Regards,

Allen

What you have described sounds basically like "Galvanic corrosion", Corrosion induced by current flow between two metals or through a system to ground. There are tests to check for this, if that is what you are asking. The loss because of this corrosion type can be measured by many of the regular available NDT technologies.

You might check www.ndt-ed.org , www.ndt.net or www.ndt.org for more info.

This message has been edited. Last edited by: Dana,

No, I am referring to residual current which could look for ground by pipes. Or for example, residual potential between oxidated areas and non oxidated areas. It is enough with some polimeter? For example, deteriorating insulators could motivate current jumping from general distribution line to the pipes in their way to ground.

Regards,

Rubén Lorenzo

R u talking about this polimeter?http://www.americanndtinc.com/associates.htm

Here is another polimeter:
http://www.polimeter.com.br/

Polimeter from Argentina:

http://www.randtplus.com/nuestra_empresa.htm

Please tell what is a polimeter used for? For checking pipe thinning?