Nonlinear contact analyses were performed with the hub disc cover and the suction/ discharge scrolls bolted to the casing. The peak von-Mises stress of the assembly, and the peak stress locations, were determined and compared to stress criteria per ASME B&PV Code Section VIII, Division 2. Using stress linearization techniques across the pump casing at this peak stress location, the membrane and membrane-plus-bending stresses were below their respective allowable limits. The local peak stresses were determined to be acceptable.
Settlement of a pipe support foundation is usually not a big deal to assess. A local piping flexibility model will reveal if the settled support keeps the pipe bending stresses within the allowable codes and, if the bending stresses are unacceptable, modifying the support and monitor periodically for further settlement is normally a quite manageable task. However, if settlement is occurring site-wide at a large site due to errors in the pre-construction soil surveys, the problem quickly becomes unmanageable.
Differential settlement can have an impact on a piping circuit in a number of modes:
1-Excessive bending stress may cause cracking of pipe and fittings.
2-Flanges may leak.
3-Elbows or TEEs may collapse.
4-Rotating Equipment Nozzles – rotating machinery is sensitive to even small amounts of deformation and are excluded from this scope.
5-Vessel nozzles – experience shows that a significant amount of deformation of a vessel nozzle due to bending can be tolerated without causing cracking or collapse of the vessel wall.
2-Flanges may leak.
3-Elbows or TEEs may collapse.
4-Rotating Equipment Nozzles – rotating machinery is sensitive to even small amounts of deformation and are excluded from this scope.
5-Vessel nozzles – experience shows that a significant amount of deformation of a vessel nozzle due to bending can be tolerated without causing cracking or collapse of the vessel wall.
* Settlement in tanks will be in two stages:
1- Settlement during Hydro Test
2- Long term Settlement
1- Settlement during Hydro Test
2- Long term Settlement
* Settlement during Hydro Test:
This is a one time settlement and usually caused due to the Hydro load during Hydro-testing before the Pre-commissioning stage.
The Tank is Hydro tested separately before connecting the Lines. Hence this settlement is not considered in our Analysis.
This is a one time settlement and usually caused due to the Hydro load during Hydro-testing before the Pre-commissioning stage.
The Tank is Hydro tested separately before connecting the Lines. Hence this settlement is not considered in our Analysis.
* Long Term settlement:
This settlement which takes place during the entire life cycle of the tank. Most settlement occurs during hydro testing of the tank. Gradual settlement continue for years since it's a slow process and it may take more years to reach full settlement. The tank settlement amount depends on soil characteristics-primarily, consolidation and compressibility.
For piping stress analysis only long term settlement is considered.
This settlement which takes place during the entire life cycle of the tank. Most settlement occurs during hydro testing of the tank. Gradual settlement continue for years since it's a slow process and it may take more years to reach full settlement. The tank settlement amount depends on soil characteristics-primarily, consolidation and compressibility.
For piping stress analysis only long term settlement is considered.
Tank bulging-radial growth occurs on the shell due to product static head for large diameter tanks. Bulge formations appear because a static head may cause circumferential and longitudinal strains.
For large-diameter storage tanks( above 36” dia ) with heavy liquid, tank bulging occurs since there is a slight growth of the tank shell in radial direction. When this radial-shell growth occurs at the nozzle location, the nozzle is rotated slightly. Even the smallest nozzle rotation will cause the associated piping to either lift-off from the first support from the tank foundation or excessively compress the pipe at the first support from the tank foundation. This happens even if the vertical displacement of the tank nozzle is in a downward direction. This condition is assumed when the first support is a rigid support from the tank foundation extension.
For large-diameter storage tanks( above 36” dia ) with heavy liquid, tank bulging occurs since there is a slight growth of the tank shell in radial direction. When this radial-shell growth occurs at the nozzle location, the nozzle is rotated slightly. Even the smallest nozzle rotation will cause the associated piping to either lift-off from the first support from the tank foundation or excessively compress the pipe at the first support from the tank foundation. This happens even if the vertical displacement of the tank nozzle is in a downward direction. This condition is assumed when the first support is a rigid support from the tank foundation extension.