Session: 10-07-01: Problem Solving Techniques in Engineering and Technology Education, Research Methodologies, Practice, Workshops and Seminars

Paper Number: 173078

Understanding Casting Products Properties and Process Quality: Case Study of Ductile Iron Valve Deficiency 

Casting is a critical manufacturing technique used to shape material, often metals, into a desired shape by pouring molten material into a mold that subsequently solidifies, forming the desired geometry. Casting has several applications in the industry, making it one of the most important manufacturing processes. The oil and gas industry are no different. In our research, we explored several aspects of the casting process, specifically when it comes to ductile iron. As a case study, we laid-out the details of a cast valve that we had at a new oil and gas facility, which failed its field hydrostatic test at as a result of its guide rib breaking away in a brittle manner. The objective of our research was to investigate the failure in order to identify the root cause and establish recommendations. We investigated and lab-analyzed the failure from multiple angles, such as valve's mechanical properties, chemical composition, microstructural graphite nodularity, and quality of casting charge material. Lab testing showed that the valve's mechanical properties were deficient, even though its chemical composition was compliant with the governing standard specification ASTM A395, and regardless of the fact that the original material test report (MTR) certified the compliance of the valve's heat lot. Microstructurally, we observed that graphite was flaky in shape instead of the ductile-iron-characteristic nodular shape, explaining the brittle behavior observed upon valve failure. This flaky shape was attributed mainly to lack of sufficient magnesium (Mg) content that serve as the nodularization agent. We also noted down the lack of any specification pertaining to Mg in ASTM A395. Lastly, we discussed how improper control and undesired intermix of different casting process lines led to contaminating our valve's properties. To tackle the aforementioned findings and increase robustness of cast parts' quality management systems, we recommended: (1) ASTM A395 to specify a required Mg content of 0.04%wt, (2) foundries to completely segregate ductile iron processing lines and recharge reservoirs from gray iron lines, (3) ASTM A395 to require additional test coupons made completely out of recharge material, whenever recharge is used, and (4) front-end customers to conduct portable hardness testing upon material receiving of cast products from foundries. In essence, the investigation methodologies, analysis, and overall thinking process involved in reaching our recommendations and conclusions are highlighted to enhance engineering knowledge-sharing and education, and in order to raise an appropriate level of awareness towards casting products properties and process quality.

Presenting Author: Mohammed Almuslim Saudi Aramco

Presenting Author Biography: Mohammed is a mechanical engineer with a Bachelor’s degree from the University of Wisconsin-Madison. He has been working with Saudi Aramco for four (4) years, accumulating various experiences within project inspection, vendor inspection, operation inspection, and static equipment engineering. So far through his career, he has been engaged with operating facilities and project management teams to provide inspection engineering consultations and assure proper implementation of inspection programs, amongst other activities. He holds several professional and technical certifications, including API 510, API 570, API 577, API 936, API SIFE, and ISO 9001 Lead Auditor.

Authors:

Mohammed Almuslim Saudi Aramco
Abdullah Al-Haidan Saudi Aramco