Detection And Evaluation Of Remanufactured Pumping Rod Base On Magnetic Memory Testing

In the sucker-rod oil production system, pumping rod is the tools to transfer power andperform movement. Once the break-off accident occurred, the oil well was forced offproduction, causes great economical loss. So oil production plant is usually replaced of oldpumping rod which is over its service life with the new one. But some of the retired pumpingrods can be used as usual, and some can be used after remanufacturing to prolong service life.In the working and handling process, different damage with type and extent may be produced.The important part of the remanufacturing is how to screen the use-value part of old pumpingrods, and give a quality appraisal to the finished product after the remanufacturing. Magneticmemory testing technology, a new nondestructive testing method, can not only discover theplastic deformation and the macroscopic of material, but also can assess the stressconcentration districts and the microcosmic of metal endangered state before the injury toearly diagnosis.This article through pumping rod metal magnetic memory testing, respectively from thegradient, peak-peak value, Area signal energy, Area signal intensity change etc makes acomparative analysis of stress concentration，micro-defect，macro-defects in the fatigue loadstates, about metal magnetic memory signal features.By pumping rod metal magnetic memory testing, this thesis analyzed respectively theyield loads stage of the pumping rod on the analysis of the magnetic memory signal features,and found the conclusion that signal curve change of MMM is reciprocating with theimprovement of fatigue cycle, and the single signal feature can not characterize the type ofdefects completely. Before the fracture, the increase of peak-peak value and area signal energyis obviously, transformation of complete rupture is higher than partial rupture. Attenuation ofsignal feature is limited in the detection range of MMM with long-time monitoring,morphology features is similar to the end of fatigue test, still characterized the surface damageor internal damage. At the same time, this article was studied on the effects of service life anddefect locations by remanufacturing or residual stress, and found the conclusion that theMMM signal is roughened on the part of residual stress, the peak-peak value and gradient areis bigger than the signal of stress concentration and microcrack.This article study is classified by statistical classification of SVM above the signalfeature of pumping rod, through multi-parameter comprehensive evaluation, to realize theblank screening and evaluation of products quality in pumping rod remanufacturing.