Need:
As part of the design and
qualification of New product development, Pythagoras Engineering Pvt Ltd were
tasked with structural integrity and Bolt assessment of OH Pump designed for
FPSO operations. The FEA analysis incorporated assessments of pump casing
during operation, structural assessment of pump supports and Foundation bolt utilization.
Scope:
• Aim of the analysis is to verify strength of the Pump & mounting
frame of FPSO. To perform the analysis, MAWP , Nozzle load, self weight and
motion loads are applied. All Nozzle loads and motion loads are applied in all possible
directions.
• Stress assessment for the following components are
discussed; base frame, motor frame, pump casing and cover plate.
• The criteria of stress assessment of the pump
casing is satisfied as per API 610 10th standard,
clause 5.3.4.
Methodology:
Linear static
structural analysis was performed on the pump assembly to evaluate the structural
integrity of pump casing, supports and bolt utilization. FE model was generated
using higher order SOLID elements. Bolts are modeled using SOLID elements with
a simplified geometry. In the first load step, bolt pre-load is applied which compressive
force at the foundation plate region and the Motor support regions. The effect
of bolt preload is locked for the successive load steps and MAWP , Nozzle load,
self weight and motion loads are applied on the system. 64 load combinations of
motion loads and Nozzle loads are considered for the analysis and the stress
are evaluated for each load combination. Stress on base frame, motor frame,
pump casing and cover plate are evaluated. Bolt utilization calculation was
performed with in line with Eurocode.
Results Outcome:
The stresses of
all the bottom support and Motor support are below the allowable stress limit
of the material.
The maximum
stress of the pump casing is greater than the allowable stress limit as per API
610.
Maximum bolt
utilization is calculated to be 0.8.