English Abstract

A Visualizing Study of Blister Fracture in Rubber O-rings

Atsushi KOGA *1
Tadahisa YAMABE *1
Hiroyuki SATO *1
Kenichi UCHIDA *1
Junichi NAKAYAMA *1
Junichiro YAMABE *2 *4
Shin NISHIMURA *3 *4
*1:NOK CORPORATION, Fujisawa-shi, Kanagawa, Japan
*2:International Research Center for Hydrogen Energy, Kyushu University, Nishi-ku, Fukuoka, Japan
*3:Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Nishi-ku, Fukuoka, Japan
*4:The Research Center for Hydrogen Industrial Use and Storage, National Institute of Advanced Industrial Science and Technology, Nishi-ku, Fukuoka, Japan
Nippon Gomu Kyokaishi,(2012),85(5),162-167 Original Paper in Japanese

In order to establish a hydrogen energy system, the reliability of sealing rubber for high-pressure hydrogen has been required. The rubber O-ring for hydrogen energy system is used with pressurized-decompress cycle of highpressure hydrogen. It causes internal cracks referred as blister fracture. Degradation of seal performance originated from blister fracture is one of the important issues to improve the reliability. This study focused on the blister initiation behavior and the effect of materials, gas species and decompression rate on blister fracture in terms of visualizing O-ring behavior under high-pressure gas. For the visualizing evaluation, a transparent ethylene-propylene rubber (EPDM) and vinyl-methyl silicone rubber (VMQ) O-rings were molded, and a special viewable high-pressure vessel with a glass viewport was developed. The O-ring specimens were exposed to high-pressure hydrogen, helium, and nitrogen at 10 MPa until gas solubility content in O-ring was saturated; afterwards, these gases were decompressed with some rate. It was obviously visualized that the blister fracture did not occur in VMQ O-ring but occurred in EPDM. The blister fracture of the EPDM O-ring in nitrogen was the most serious in the tested gases. These blister behaviors are considered to be related to gas diffusivity of hydrogen, helium and nitrogen.

Keywords: Rubber, O-ring, Blister, Fracture, High-pressure gas, Decompression speed