How do you seal an un-centered carrie pipe?

Sealing Between Casing and Carrier when Carrier Not Centered

     There are several products out there today that can be installed to seal up the space between a casing and a carrier pipe.  Why is this done?  First and foremost, because the DoT requires that it is done!  Beyond that though, the idea that water and air (and who knows what else) might get into a casing pipe and sit there rusting it away for who knows how long in who knows how short of an amount of time is a terrifying one.  A rusted out casing pipe, collapsing onto a coated carrier pipe -- and all of that underneath some kind of a road or highway that will experience significant vibrations and movements would be an absolute recipe for disaster.

Caseal - quick, easy and reliable method for sealing a casing

     So what are your options?  There are really two different technological options that I am aware of (sure there are others; but only two worth mentioning in my opinion). 

     First:  Mechanical seals.  These are generally put together using different links of rubber and plastic type materials to properly fill the space around the casing and act as a centering mechanism.  These are put together mechanically.  One downside to this technology, when a carrier pipe is not centered within the casing for some reason - these types of systems will not work. 

     Second:  Heat Shrinkable.  These are generally wrapped around the casing/carrier intersection and utilize an aggressive mastic sealant to bond to both the casing pipe and the carrier pipe; forming a water proof barrier that will prevent any type of substance from getting into that casing pipe.  With a wide range of use options, Caseal can be installed quickly and easily on just about any casing/carrier diameter combination.  One downside:  the Caseal does not act AS a spacer or centering device.  The Caseal only seals.

     Most of the time, what I see is contractors and end users deciding to actually install both products as a sort of belt and suspenders system.  Why?  Because the minimal cost associated with using both products is peanuts when considering what the cost would be to deal with a heavily damaged casing pipe down the road.  Pay just a few extra dollars today....or pay tens of thousands of dollars in the years ahead?  Seems like an obvious choice!