Wavelet domain adaptive filtering algorithm for removing the seamless pipe noise contained in the magnetic flux leakage data

With the widespread application and fast development of gas and oil pipeline network in China, the pipeline inspection technology has been used more extensively. The magnetic flux leakage （MFL） method has established itself as the most widely used in-line inspection technique for the evaluation of gas and oil pipelines. The MFL data obtained from seamless pipeline inspection is usually contaminated by the seamless pipe noise （SPN）. SPN can in some cases completely mask MFL signals from certain type of defects, and therefore considerably reduces the detectability of the defect signals. In this paper, a new de-noising algorithm called wavelet domain adaptive filtering is proposed for removing the SPN contained in the MFL data. The new algorithm results from combining the wavelet transform with the adaptive filtering technique. Results from application of the proposed algorithm to the MFL data from field tests show that the proposed algorithm has good performance and considerably improves the detectability of the defect signals in the MFL data.

Investigation on Mechanical Property of Seamless Pipe

The mechanical properties of the steel pipe rolled with continuously casting round billet after determining the chemical composition in steel were studied.The results show that the total reduction ratio should be higher than 5.2 when the line pipes of grade B,grade 20 and other general seamless pipe were rolled with continuously casting round billet.And the total reduction ratio should be higher than 10.2 and the grain size should be controlled more than grade 7 for casing of oil countryside tubular goods(OCTG).

Stress Relaxation of Grouted Entirely Large Diameter B-GFRP Soil Nail

One of the potential solutions to steel-corrosion-related problems is the usage of fiber reinforced polymer （FRP） as a replacement of steel bars. In the past few decades, researchers have conducted a large number of experimental and theoretical studies on the behavior of small size glass fiber reinforce polymer （GFRP） bars （diameter smaller than 20 ram）. However, the behavior of large size GFRP bar is still not well understood. Particularly, few studies were conducted on the stress relaxation of grouted entirely large diameter GFRP soil nail. This paper investigates the effect of stress levels on the relaxation behavior of GFRP soil nail under sustained deformation ranging from 30% to 60% of its ultimate strain. In order to study the behavior of stress relaxation, two B-GFRP soil nail element specimens were developed and instrumented with fiber Bragg grating （FBG） strain sensors which were used to measure strains along the B-GFRP bars. The test results reveal that the behavior of stress relaxation of B-GFRP soil nail element subjected to pre-stress is significantly related to the elapsed time and the initial stress of relaxation procedure. The newly proposed model for evaluating stress relaxation ratio can substantially reflect the influences of the nature of B-GFRP bar and the property of grip body. The strain on the nail body can be redistributed automatically. Modulus reduction is not the single reason for the stress degradation.

Review of research developments of 12Cr1MoVG heat resistant steel in China

In this paper, we review the evolution of 12CrlMoV steel standards at home and abroad, analyze the effects of various elements and determine their optimal contents in steel. The influence of heat treatment and microstructure on the creep strength of 12CrlMoV steel is investigated. Statistical results from conventional mechanical properties, ductile-brittle transition temperature, high temperature oxidation resistance, aging, instant high temperature properties, and creep are introduced. The results show that the chemical composition and heat treatment process of 12CrlMoVG steel identified in the GB 5310 - 2008 standard is appropriate, resulting in a steel with higher creep strength and good comprehensive properties.

In-Situ Austenite Steel Matrix Composite Reinforced by Granular γ+（Fe,Mn）3C Eutectic

The mechanical properties of the steel pipe rolled with continuously casting round billet after determining the chemical composition in steel were studied. The results show that the total reduction ratio should be higher than 5 2 when the line pipes of grade B, grade 20 and other general seamless pipe were rolled with continuously casting round billet. And the total reduction ratio should be higher than 10 2 and the grain size should be controlled more than grade 7 for casing of oil countryside tubular goods (OCTG).