The set of activities intended to ensure their products which can be goods and/or services, is getting crucial to the successful business in almost competitive markets. Though the mass production fields like electronics and automotive industries have matured and versatile methodologies on quality issues, in the case of small quantity batch processes especially after various manufacturing processes, problems of quality assurance highly depends on determination by the intended users, clients or customers. This study suggests digital simulation processes to cover wide categories of products required expensive real experiments under specified hydro-pressures. To cope with the diverse changes after manufacturing from nominal thickness of raw pipes, all geometry modeling reflected measured thickness distributions over specified points and validation tests for numerical simulations were performed to minimize the number of product disposals as the process of design proof tests. Through this project, the manufacturer established a business process of numerical simulation and validations, which make it possible that they are very confident from early stage of bidding to service steps after deliveries in terms of not only technical power but overall quality assurance, because they successfully attained meaningful agreements with major clients by proposed digital simulation process in this paper.