Process for welding pipe ends and an insulating ring therefor

DETAILED DESCRIPTION The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1.
In a process for joining together a pair of aligned end sections of steel pipe, internally filled with liquid, utilizing a cylindrical steel sleeve positioned over the junction between adjacent pipe ends and welded thereto by means of circumferential fillet welds, the improvement comprising: positioning a composite ring, comprising a body of heat-insulating, liquid-disintegratable material coated with a liquid-impermeable material which dissolves slowly in the pipe liquid, within each pipe end section and contiguous thereto, beneath the anticipated area of the circumferential fillet weld, whereby the rate of heat transfer from the weld and pipe end to the liquid in the pipe will be reduced during the welding process; fillet welding the sleeve ends to the pipe end sections with the insulating rings positioned therein; and subsequently disintegrating the rings in the liquid.




Description:
FIELD OF THE INVENTION The invention relates to an improvement in the process of replacing a section of a high pressure steel fluid transmission pipe line.
More particularly, the invention has to do with the joining of each pipe end of the old line with an end of the newly installed replacement section.
This joining procedure involves positioning a sleeve over the junction between the old pipe end and the replacement section and welding the sleeve to each of the old pipe and the new section, by means of circumferential fillet welds.
The invention involves providing removable insulation internal of the pipe ends beneath the weld areas, to reduce the cooling rate of the pipe wall and thereby diminish embrittlement.
BACKGROUND OF THE INVENTION In the high pressure fluid transmission pipe line industry, it is common practise to remove a length of the line and replace it with a segment of new pipe.
This is done to remove a length of pipe having a defect in its wall or to install new valve equipment and the like