18" Cast Iron Pipe Needs to be Capped

[syence]

First off, I'm a civil engineer with a mechanical problem that I was hoping someone here could assist with resolving. I'm looking for a method to sufficiently cap an abandoned pair of underground 18" condenser pipes (pipes currently sit on a concrete cradle). My initial thought was to cut the pipes and weld a 1/2" think steel plate (continuous fillet weld 1/2" thick); however, this will be very difficult since access to the bottom of the pipes is very limited due to the trench box and excavation limits. Is there a mechanical fitting (I've read about dresser couplings or megalugs??) that I can use in conjunction with some sort of plug and to cap the pipes? I've attached a picture of the pipes for clarification. If so, can someone assist with suggesting a type and/or model fo such a fitting?

Otherwise, would installing a plug (mechanical or inflatable - not sure which is best here) and blocking the pipes with concrete be a sufficient capping method?
Any help would be greatly appreciated.

Thanks

 

[bimr]

If you are abandoning the pipes, use a 2 foot plug of concrete and a megalug. That will provide a permanent closure

http://www.ebaa.com/files/pdf/brochures/Brochure.1100.pdf

Welding is not a practical solution.

 

[syence]

Thanks, but can these megalugs be used on cast iron pipes? The product data states it's dor ductile iron.

 

[rconner]

If the pipes will never again be pressurized, I suspect you really may not need a restraint (e.g. retainer gland). If the pipe is of "A-B" or modern OD pattern (~19.5" diameter, as could be measured/determined before cutting with a circumference tape) and if the wall is in good shape, the ends of the cut pipes could be sealed with a modern mechanical (MJ) joint ductile iron cap, standard unrestrained MJ gland (or retainer gland like Megalug, but without setting restraints), and of course an MJ gasket compressed on the outside of the pipe surface with bolting between the gland and the mating cap flange (stuffing-box principal).

 

[bimr]

Megalugs mechanical joint caps are suitable for cast iron or ductile iron.

http://www.ebaa.com/files/pdf/connections/Connections.PD-04.pdf

 

[cvg]

if you are just abandoning a pipe, a concrete plug is usually sufficient, cheap and easily done. no additional fittings are necessary. yes, dresser makes a line cap that could be used, but it might be a lot more expensive than just concrete.

http://www.water.ca.gov/regulations/docs/013015/Dresser_Style_63_expansion_joint.pdf