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Vol.11 No.3previousAA SP21 (AA163-164) NT95

Academic Articles
Regular Paper Vol. 11 No. 3 (2019) p.111 - p.117

Application of Ice Plug Technology to Nitric Acid Pipe Systems


Daiki OSANAI1,*, Tomohiro ICHIKAWA1, Ken SATO1, Wataru NISHIYA1, and Masaki HOSOGOE1

1 J-tech Co., Ltd., 1-108, Aza Iyasakadaira, Oaza Obuchi, Rokkasho-mura, Aomori 039-3212, Japan

At the maintenance of hydraulic pipe system during continuous operation in many industrial plants, an ice plug technology for temporary partial isolation is generally applied. We have been developing ice plug technology in order to apply to nitric acid pipe systems. As chemical reagents such as nitric acid possess volume shrinkage characteristic in contrast to water, we implemented mock-up test in order to study specific freezing process of nitric acid and application ability of the ice plug technology.
Consequently, we confirmed nitric acid transferred completely to white solid phase around -60 °C to -70 °C. Furtehrmore, in mock-up test, approximate 40 °C of freezing point depression originated from freezing concentration process of nitric acid was observed. It did not affect ice plug formation, it was possible to form ice plug possessed sufficient pressure resistance performance with freezing completion time of estimated freezing process.
Ice plug technology, Nitric acid pipe system, Volume shrinkage characteristic, Freeze concentration process, Freezing time
Full Paper: PDF EJAM Vol. 11 No. 3 pp.112-117 " Application of Ice Plug Technology to Nitric Acid Pipe Systems"
Article Information
Article history:
Received 18 October 2018
Accepted 28 October 2019