Extreme Pressure Equipments

Pressure equipments in the process industries and the newly developing industries usually have extreme sizes and/or are subjected to extreme operating conditions such as high pressure,blast loading,cryogenic temperature,elevated temperature,complex corrosion,and so on.In order to understand,research and develop these equipments systematically,a concept of extreme pressure equipments（EPEs） is proposed.The applications and demands of EPEs in petrochemical industry,coal chemical industry,advanced energy,military,space technology,and environment protection are introduced.Basic scientific problems in material,design,inspection, and safety related to EPEs are discussed.Then,take chemical composition,manufacturing process,service duration,and operating conditions for example,main factors which affect material properties of EPEs are analyzed.New design concepts including design based on life cycle,dynamic design and light-weight design are introduced.EPEs with higher efficiency,lower cost and safer performance are in urgent demand in national major projects including ten million ton oil refinery,one million ton ethylene,liquefied natural gas transportation,and nuclear power plant.Thus,further research should be conducted on information acquisition, multi-mechanism damage coupling model,damage inspection,life prediction,online safety monitoring,maintenance strategy,safety pre-warning system,and emergency system.

Experimental research on unloading properties of clay under high stress

Abstract： Mechanical properties of clay under high stress are quite different from those under low stress. It is necessary to investi- gate unloading properties of clay under high stress for the design and construction of deep underground engineering projects. A series of experiments were conducted to investigate the unloading properties of clay under high confining pressures by using a SKA-1 high pressure consolidation instrument designed by us. The stress versus strain relationship and the way that K0 values of clay change during the loading-unloading process were discovered. The results show that there are clear differences in the state of stress and deformation behavior of the clay along different unloading paths.

A new method of studying collapsibility of loess

A new triaxial testing system that could control suction in wetting-induced collapsible tests was success-fully developed to study the suction effects on wetting-induced collapsible deformation.The pedestal of the triaxial cell was made up of two parts,and the equipment not only could control suction but also could make water accessible to soil.A pressure/volume-controlled equip-ment was combined with the triaxial system to measure the water volume absorbed by samples accurately and to add pressure on water to filtrate into the sample.The apparatus could measure volume change precisely and keep the deviator stress unvaried,as well as measure the volume of water filtrating into the samples exactly.A triaxial collapsible testing procedure was described using the new apparatus for undisturbed collapsible loess with controlled suction.Furthermore,a series of double triaxial collapsible tests were conducted under different suctions and the same net cell pressure,and tests under different net cell pressures and the same suction were also done.It was indicated that the collapsible deformation increased with the increasing suction,and the effect of the net cell pressure on collapsible deformation was remarkable.The new triaxial apparatus was a useful facility to study the collapsible behavior of loess.