Steam stop valves are generally used in steam boiler plants to regulate the flow of steam from boiler to main steam pipe with the help of movable plug (disk/seat/seal). The flow can be completely shut off by moving the plug against the flow until fully closed. It is generally an angle pattern globe valve. In this project, thermostructural analysis of a steam stop valve was performed in order to analyse some of the important components of this valve under high temperature and pressure. The base geometry was provided by amir and simplified for the analysis. After simplification, the geometry was uploaded and meshed using parametrized tetrahedralization on SimScale platform. The geometry and mesh are shown in the figures below.
For the analysis, steady-state thermostructural analysis was selected since temperature and pressure was considered static. Ductile iron (spheroidal graphite (SG) iron) was selected for the whole body whereas rubber was selected for the seat/seal. Temperature and pressure of 573K (300oC) and 0.65 MPa was applied to the internal surfaces of the housing whereas heat convection of 20 W/(m2K) was applied on the outer surfaces. The result below shows the temperature and heat flux in the valve.
Finally, the figures below show the vonMises stress and strain magnitude in whole body and seal respectively. It can be seen that there are maximum stresses in studs near yoke and cover making them most sensitive portion of the valve whose strength should be taken into consideration, whereas seal incorporates high strain values due to it’s less stiffness.