b through which the conveyed liquid may flow from the main pipeline 100 to the auxiliary pipeline 144 therefore the open insertion shoe 112 is suitable for use when the auxiliary pipeline 144 is to remain in use after the retrofitting operation as discussed below the present operation also contemplates so called u201c closed u201d embodiments wherein the insertion shoe is without openings so that the opening 116 to the auxiliary pipeline 144 is completely blocked upon installation of such a closed insertion shoe the auxiliary pipeline 144 may be scraped in general the only difference between an open insertion shoe and a closed insertion shoe in accordance with the present invention will be the presence or absence of such openings and an example of such a closed insertion shoe 212 is illustrated in fig7 as being identical to the open insertion shoe 112 except for having no openings in the plate 234 therefore the description of any features in the various openings in the plate 234 therefore the description of any features in the various embodiments other than such openings is applicable to both types of insertion shoe the insertion shoe 112 of fig3 includes a structure for connecting the insertion shoe 112 to the t section 120 including a main guide rod.