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NS Styrene Monomer Co., Ltd. Oita Works

With styrene monomer as its main product, NS Styrene Monomer Co., Ltd. (NSSM) meets a wide range of industrial needs. After repeated valve failures, the company’s Oita Works plant is now introducing smart valve positioners. The plant is also using a system to improve the monitoring of valve status. In this way, by providing a mechanism to track valve failure trends, a high level of plant operation stability is being achieved.

Upgrade to high-performance positioners after repeated valve failures

NSSM meets a wide range of industrial needs with its main product, styrene monomer, which is the raw material for resins like ABS (which is frequently used in food containers and household appliances) and for aromatic compounds like benzene, toluene, and xylene.

In Oita Works’ chemical plant, which is located in the Oita Petrochemical Complex, a total of four plants are operating: an aromatic production facility, two styrene monomer production facilities, and a divinylbenzene production facility.

“Each plant has been in production for many years since the beginning of operations, which was from 1977 to 1990, but many valve failures have occurred, especially since 2009. In investigating the cause, we found that about 40% of the failures were caused by age-related malfunction of the positioner that controls the opening of the valve,” says Junji Yamamoto, leader of the Engineering & Maintenance Group.

In view of this situation, the plant decided to begin changing the valve positioners at each plant from the conventional mechanical type to a high-performance type equipped with a microprocessor. Azbil Corporation’s smart valve positioner was selected for the job.

“At that time, Azbil was particularly advanced in making positioners smart. Azbil’s positioners also have the great advantage that they can be attached to valves made by other companies, so we can use the same kind of spare parts for all the positioners,” says Ryusaku Uwamukai, manager of the Engineering & Maintenance Group.

These case studies were published in the 2020 No. 1 issue of the azbil Group's corporate magazine, azbil.