The eddy current testing technique in the petrochemical system

Abstract :This paper introduces a nondestructive testing method, the electromagnetic eddy current technologyTo solve the petrochemical industry exchange a lot of heat exchanger for quick check in service 

Has detailed expression on detection principle，program implementation defect evaluation.

Keywords: eddy current thickness detection in service inspection

Electromagnetic eddy current testing is one of the five major routine nondestructive testing technology, especially in recent years, regardless of the instrument and testing technology has been great progress, in the petrochemical, electric power, metallurgy, and other industrial fields has played an increasingly important role. This article only from petrochemical system heat exchanger in service inspection of this project to introduce the practical application of this technology and important significance。

Widely used in petrochemical industry, the various forms of shell and tube type heat exchanger, there are a lot of heat exchanger in high temperature, high pressure and strong corrosive medium, such as medium corrosion, erosion, fatigue stress, shell and tube wall causes various corrosion defects, damage, and wall thickness thinning, this will be a serious threat to the safe operation of equipment. So for periodic testing of the heat exchanger tube in service grasp the existence and development situation of defects, is to ensure that the whole equipment is the key to the safe operation for a long period of time。

In the present several kinds of commonly used in nondestructive testing technology, the electromagnetic eddy current testing method because of the fast detection, high sensitivity, non-contact detection, etc, thus become the heat exchanger tube of the only effective means of detection。

1. detecting principle

The electromagnetic eddy current testing is the theory basis of electromagnetic induction ,connect high frequency alternating current to stimulus coil of probe ,In the measured near the wall will be induced eddy current, tube geometric defects, the electromagnetic anomaly and size changes,Would affect the tube eddy current, and the change of the eddy current changes detecting coil impedance and induced voltage 。