Rotten 5" cast repair?

[JCplumb]

My mate is trying to open a pub in Blackpool, after a couple of weeks patching up the neglected building he has come across this 5 inch cast pipe that serves the 1st floor. Any time something is used upstairs it's messy downstairs because of the rotten pipe shown in the pic below.
I've not seen this as he just found it and sent me this pic asking for advice.
My advice was to cut it all out and replace the whole section (it's a 10m horizontal run) but he informs me there is no access at all to do that.
Is there a way to repair this bearing in mind the access is really bad and he had to cut through the back of a bar to get the access he has now which is about 18 inches?

 

[gasmanrob]

I know you can line underground but not sure about internals. Worth looking at

 

[stevetheplumber]

never seen 5 inch 2,3 3.5,4,6 but never 5

 

[lame plumber]

time to bite the bullet if its that bad it will all be bad

 

[JCplumb]

Thanks for the tips guys.
Lining may be the option he takes, he's sunk a fair bit of money into this so far and needs it to open asap.
I haven't seen the pipe so couldn't say if it is 5", I'll probably be nipping over there tomorrow to get eyes on it.

 

[Geyser]

Replace best option of course but not allways possible or feasible. Have a look at some of the rust converter products available for cars and boats that can be sprayed on. Im a landrover owner so i need some as well!! Could buy him some time until replacement.

 

[kozak1968]

Back in the day we used plastic padding car filler to repair cast iron interceptors that had cracks in the casting. Their was no option of sending them back, these things were made to order.