On January 9, Kansan Corporation obtained Ministry of Economy, Trade and Industry (METI)’s special certification for the implementation of the ultrasonic testing (UT) to retest a seamless medium-sized cylinder for semiconductor gas with a capacity of 47ℓ at Kansan’s Takasaki Operations. Though applicable to only designated specialty gases, it now enables Kansan to carry out retesting without using the conventional hydraulic testing method.

Kansan has been doing and developing the retesting business of ultraclean cylinders for semiconductor gas for more than 20 years. As many of such cylinders are also distributed abroad, there have been increasing requirements to meet the US DOT Standard. In September 2006, in order to respond to such trend, Kansan got the certification of DOT hydraulic retesting and started its testing procedures. As in some cases it is impossible to pour water into cylinders depending on gases to fill and there are increasing requirements for the UT inspection on the DOT-spec cylinders, Kansan got DOT’s SP (special permit)-14206 for ultrasonic testing in April 2010. Retesting of cylinders started using ultrasonic wave keeping the valve attached without any exposure of the inside of cylinder to atmosphere or water. The UT technology and equipment based on the DOT certification was introduced from Digital Wave of USA.

In August 2013, appreciating Kansan’s accomplishments, Toshiba asked Kansan for a technological collaboration with interest to introduce UT into the current Japanese testing method of cylinders.

Toshiba has once started an attempt to deregulate by introducing UT for enhancement of global competitiveness for reason that the hydraulic method indispensable for the Japanese cylinder retesting method requires much time and costs to recover cleanliness removing the contaminants on the inner surface of cylinder by water and air at the time of retesting.

The applicable cylinder must be a 47ℓ seamless cylinder which is polished with 25µm or less roughness of inner surface treatment, the inner dew point is maintained at less than minus 60℃and the same type of gas is used.

There are 33 applicable gases in total including 23 gases of the single type ranging from etching gases (carbon tetrafluoride, trifluoromethane, nitrogen trifluoride, hydrogen bromide, chlorine, etc.) to CVD gases (silane, disilane, ammonia, nitrogen monoxide, methane ethylene, etc.) and 10 mixed gases like fluorine/nitrogen and argon/xenon/neon.

Cylinder retesting is now on the way toward deregulation to cope with the globalizing trend and also there seems to be a possibility to introduce a non-hydraulic method like UT or acoustic emission.