Abstract: Disclosed is a technique whereby when multi-component liquefied gases such as liquefied natural gases (LNG), liquefied petroleum gases (LPG) or the like which are different in composition, density or the like are stored in the same storage tank, any stratification of the liquefied gases within the storage tank is prevented.The introduction of the liquefied gas into the storage tank is accomplished in such a manner that the introduced gas enters the storage tank in the form of a jet of liquefied gas which is shoot out from near the tank bottom obliquely upwardly with an ascending vertical angle in a predetermined range and reaches or comes near to the free surface within the storage tank, and in this way the desired mixing of the introduced liquefied gas with the liquefied gas previously existing in the storage tank is effected as soon as the introduced liquefied gas enters the tank.

Abstract: A butt welded tube is provided having excellent properties by the steps of forming a skelp onto a round shape, butt welding the edges thereof with butt welding rolls, blowing oxygen or air into the weld zone, so that said zone is brought to a melted condition with oxidizing heat based on said blowing and some notches which are formed are blown off with said blowing, and then said tube is passed through a train of reducing rolls to obtain a smooth surface and the required dimension of said tube.