Field Signature Method Research Articles

Development of FSM corrosion monitoring system based on Cloud Server

FSM (field signature method) is a new non plug-in on-line monitoring method for pipeline corrosion. The traditional FSM corrosion monitoring equipment is generally a single machine to copy data or collect terminal client wireless transmission data, which is not convenient for data management. In this paper, cloud service is introduced into the monitoring system, and the FSM corrosion monitoring system based on cloud server is developed, which realizes the functions of real-time, online and remote control. The monitoring system can obtain the current status data of the monitored pipeline in real time, and calculate the corrosion parameters of the pipeline according to the data sent back by the measuring device. The system can draw trend diagram and morphology diagram according to the calculated corrosion parameters, display database data tables and relevant charts, and send monitoring information regularly.

Application of Lock-in Amplifier Technique in AC FSM based on AD630

Field Signature Method (FSM) is one of non-intrusive technique for pipeline internal corrosion monitoring, but the commercial FSM systems nowadays are all using DC input which have many shortcomings. In this paper, AC FSM based on AC input has been developed, DC FSM can be replaced by AC FSM with low-frequency. To extract weak signals, the lock-in amplifier based on AD630 has been designed and manufactured, the functions and designed circuits of each part have been proposed. Experimental results show that, the application of lock-in amplifier technique in AC FSM based on AD630 can measure the weak signal from the noise interference effectively, ensuring the accuracy and security at the same time.

A Novel Design of Modular Field Signature Method Monitoring System

The authors developed a novel modular field signature method monitoring system with the characteristics of low motivation, high precision and integration. The hardware system is built based on the PXI bus technology, the software is independent programmed by LabVIEW programming environment provided by National Instrument (NI). The operation of the system is highly simplified, according to the demand it can accurate real-time information. This system is qualified with the traits as follow: improve the safety and accuracy of the experiment, reduce the experimental time effectively, and improve the efficiency of experiments.

New feature for evaluation of subsurface defects via multi-frequency alternating current field signature method

A multi-frequency alternating current field signature method (MACFSM) that combines multi-frequency excitation and zero phase is proposed to detect subsurface defects in metal pipes. In a numerical analysis, multi-frequency exciting currents are applied to a metal pipe (wall thickness T = 10mm) which contains different depth defects, and then zero phase is extracted from phase spectrum to assess defect depth. The investigation shows that in comparison with derivative extremum, the monotonic relationship between zero phase and defect depth can enable accurate determinations of defect depths. A general solution for calculating defect depth using zero phase is given in MACFSM. Pulse excitation field signature method is proposed for future research of quantitative nondestructive evaluation (QNDE) in the end of this paper.

Investigation of pitting corrosion monitoring using field signature method

The field signature method (FSM) is a nondestructive testing (NDT) method based on the potential drop (PD) technique and has been applied to online metal pipe corrosion monitoring for nearly three decades. The many advantages and benefits of the method have been reported in a number of studies, but few have reported on its limitations or shortcomings. However, the detection accuracy for pitting corrosion in FSM is very low. In this paper, the reasons for the low pitting corrosion detection accuracy of FSM were analyzed and it was found that different corrosion pits, which have different sizes, depths or positions, generally have differing influences on the potentials of nearby electrode pairs. Therefore, a new method using a subdivided resistor network to assess pitting corrosion is proposed and verified. When compared with the traditional method, the most important parameter, namely the pitting corrosion depth detection accuracy, can be significantly improved.

Improved formula for localized corrosion using field signature method

Field signature method (FSM) is based on a potential drop (PD) technique and has been applied for nearly three decades for online metal pipe corrosion monitoring in many industrial areas. However, the detection precision of FSM for localized corrosion is still very low because the current field distribution in the measured pipe will be changed during the corrosion process but the formula used to assess corrosion-depth at present ignores the changes. This paper proposed an improved formula to calculate localized corrosion. The theoretical analysis and experimental results verified that the evaluation accuracy of FSM for localized corrosion can be greatly improved by this new formula.

High-accuracy evaluation of pitting corrosion in field signature method

High-accuracy evaluation of pitting corrosion in field signature method

Investigation of drag effect using the field signature method

The potential drop (PD) method is an established non-destructive evaluation (NDE) technique. The monitoring of internal corrosion, erosion and cracks in piping systems, based on electrical field mapping or direct current potential drop array, is also known as the field signature method (FSM). The FSM has been applied in the field of submarine pipe monitoring and land-based oil and gas transmission pipes and containers. In the experimental studies, to detect and calculate the degree of pipe corrosion, the FSM analyses the relationships between the electrical resistance and pipe thickness using an electrode matrix. The relevant drag effect or trans-resistance will cause a large margin of error in the application of resistance arrays. It is the first time that the drag effect in the paper is investigated and analysed in resistance networks with the help of the FSM. Subsequently, a method to calculate the drag factors and eliminate its errors is proposed and presented. Theoretical analysis, simulation and experimental results show that the measurement accuracy can be improved by eliminating the errors caused by the drag effect.

Study on Application of Field Signature Method (FSM) to Fatigue Crack Monitoring on Steel Bridges

Recently, a number of fatigue cracks have been detected in orthotropic steel decks in Japan. An effective inspection method for detecting and monitoring crack is strongly needed. In this study, Field Signature method (FSM), which is one of the Non-destructive inspection methods and has been already applied to detect corrosion or a section reduction of the plumbing in a power station and various plants, was focused. FSM system was applied to a couple of real steel bridges which were under different conditions during this study. Finally, an effectiveness of the system for monitoring fatigue cracks on steel bridges has been verified.

FSMによる鋼床版の疲労き裂発生と進展の監視

Fatigue test for the steel plate deck was carried out by using the wheel load traveling test machine. The position where fatigue crack initiation was specified by FSM (Field Signature Method) could be confirmed by visual inspection (9-11)×104 cycles later. The time of initiation of small crack (less than 150mm), which cannot be confirmed by visual inspection, could be specified by FCs value that is the deviation of FC value. The direction of propagation and the length of fatigue crack could be specified.Being conscious of the site, it was investigated whether initiation and propagation of fatigue crack can be detected with high accuracy and extensively or not by impressing pulse current in the wide range (1200×1600 (in mm)) and by extending the distance (80, 160 and 240 (in mm)) between pairs. Although FC value became small as the distance extended, FC values increased with the similar tendency. So, specification of fatigue cracks was not difficult.

Monitoring of Initiation and Propagation of Fatigue Crack by Field Signature Method

Monitoring of Initiation and Propagation of Fatigue Crack by Field Signature Method

New technique monitors; pipeline corrosion, cracking : Strommen, R.D.; Horn, H.; Wold, K.R. Oil and Gas Journal, Vol. 91, No. 52, pp. 88–92 (27 Dec. 1993)

A new technique for monitoring the conditions of an in-service pipeline, continuously monitors corrosion taking place at a given point on the pipeline and remaining pipe wall thickness at any time. The Field Signature Method (FSM) has been field tested on a flow line on Shell Expos Dunlin A North Sea platform. The technique combines the advantages of corrosion probes and of non-destructive testing (NDT) inspection by being highly sensitive and responding to changes in corrosion of the actual pipe wall. It can cover relatively large areas. The FSM method is based on feeding an electric direct current through the selected sections of the structure to be monitored and sensing the pattern of the electrical field by measuring small potential differences set up on the surface of the monitored object. The FSM measures all electric potentials and compares them with initial values measured when monitoring of the object started. These values represent the initial geometry of the object and may be regarded as the object's fingerprint. Proper interpretation of these potential differences, or rather of changes in potential differences, can lead to conclusions about, for example, general wall-thickness reduction.

The FSM method for monitoring process pipelines offshore : Daaland, A. Insight, Vol. 38, No. 6, pp. 434–439. (Jun. 1996)

The demand for corrosion monitoring systems in the oil industry is increasing. Oil companies these days are focusing on regularity, security and maintenance as areas that are important to develop. Monitoring systems are of great importance in this respect. For monitoring corrosion, corrosion probes are widely used at present. Probes monitor indirectly the corrosion attack. This means that probes are not measuring where it actually corrodes. The Field Signature Method (FSM) eliminates this problem to some extent. FSM measures in a predetermined area where corrosion attacks are likely to occur