1. High Pressure manifolds analysis conclusion
1) From the stress distribution of High Pressure manifolds visible, either Pup joint, Swivel joint, Tee, or Hammer union, should the power level gradually decreases from the inner wall of the tube wall. Should force the highest level in the tube wall, because the work load directly on the tube wall.
2) the distribution of high stress areas. In Pup joint, the inner wall of the high-gravity area undoubtedly tube: elbow in activity in areas of high stress in the inner wall surface of the elbow; the high stress area of ​​the armpit Tee competent and inclined tube intersect, Tee's armpit is stress concentration area. This is entirely consistent with the conclusions of the qualitative analysis, also in line with the structure of the mechanical properties.
3) exceed the standard stress. The results can be seen from the finite element method, the work load for the import Tee action under 100Mpa, directors and oblique intersection pipe stress armpit up 759.633Mpa, in fact, this is not true stress at armpit. That is the true stress Tee's reach so high. The reason of this magnitude is Tee stress caused by the finite element model, a finite element model of the formation of a sharp point in the armpit Tee cause stress concentration, but not the actual structure of the cusp.
Design life of 4) pipe is generally 10 to 15 years can be considered, in addition to the wall thickness of the manifold components should meet the strength requirements, but should also include corrosion, wear and tear, such as the manufacture of negative deviation left margin, the annual erosion rate is preferable 0.1 mm. High Pressure manifolds for all members by attrition thickness 2mm calculate the stress and still meet the normal requirements.
5) From the results of domestic and imported materials, two High Pressure manifolds look, High Pressure manifolds with strong rigidity.
6) Tee high stress area is located two intersecting armpit. Mises stress most of the manifold between 300Mpa to 370Mpa, low strength reserve role in the work load 100Mpa.
7) use of alternating loads relatively low number of High Pressure manifolds, so whether it is with fatigue theory or analysis results obtained by crack propagation theory suggests safe life of High Pressure manifolds are more than 20 years.
2. High Pressure manifolds proposal and outlook
1) based on the archives service manifold, performed every 2 to 3 years to give a comprehensive maintenance and inspection, content inspection, including usage, the degree of wear, corrosion and unexpected accidents. When a crack is found, the results of this study should be controlled, if the crack is in a safe state, the member can still be used, but should be extended to observe changes in the crack, so that timely diagnose problems and ensure safe and reliable operation High Pressure manifolds.
Theory and Method 2) of this study can be generalized to the petrochemical industry, various types of High Pressure manifolds damaged forecast. For the working pressure increases, increasing the number of alternating load, accidental injury when many other factors change, and for this study did not relate to other types of high-voltage parts can employ the method of this study, in order to make the corresponding high-voltage parts broken prediction .
Fatigue Fracture 3) high-pressure pipeline and High Pressure manifolds, and currently still linear elastic stage, for the calculation of the crack tip plastic zone are also based on the analysis based on the elastic and take appropriate correction approximate answers. Fracture mechanics and many formulas are some empirical formula outstanding solid theoretical foundation, therefore, should the macro and micro fracture mechanics combined mechanism of cracks starting from, to study the fracture mechanism, to get a more precise answer, and Fracture Analysis of the results of the research gradually applied to the High Pressure manifolds and other pressure vessels, therefore, this research has yet to be further developed.