shower drain in an old school building

your images are missing but i'm thinking lead and oakum?

is there a bomb shelter under that bathroom?

Not a plumber but I looked up the diameter of Ex heavy and service weight CI pipe and hubs and I saw nothing that was 3 1/4".

You will need to chip away the outer diameter of the pipe and use that as your connection.

When it's that deep into the floor, I would use a four-band no-hub clamp, or a reducing four-band clamp.

From the look of it from here, probably a 4 x 2 or a 3 x 2. That is, unless a hub appears when you chip the cement away from the outer diameter of the pipe, then you would need a push gasket.

Push gasket

Four-band no-hub clamp.

That looks to be a slightly oversized hub for 2" extra-heavy cast iron soil pipe.

Cast iron pipe comes in two sizes, "service" and "extra-heavy." You can see a chart of dimensions here: https://www.engineeringtoolbox.com/cast-iron-soil-pipe-dimensions-d_1751.html

Extra-heavy in 2" has a hub inner diameter of 3.06".

The fitting you need is a Fernco donut: https://www.supplyhouse.com/Fernco-22UX-205-2-x-2-Compression-Donut

That will allow you to transition to 2" PVC. Will that work? I don't know. Fernco makes two sizes of the donut, for service and extra-heavy, even though the hub inner diameter only varies by 0.12", or 1/8". Your hub looks to be about 3/16" bigger than extra-heavy.

The donut is only about $8 so it's worth trying. If it doesn't work, you can do it the old school way, pack the joint with oakum and seal it. You can pour lead on PVC, but there is a modern sealant specifically made to be a cold replacement for lead in these kinds of joints:

https://www.supplyhouse.com/Hercules-25215-Plastic-Seal-10-3-oz

If the Fernco donut makes a mechanically sound joint — ie, it stays together — you can also use the sealant with the donut.

Lots of good info in this Tyler Pipe booklet attached. Pg. 103 has some dimensions

your attachment is just a bang graphic that says "unsafe" if you hover over it. not sure if it needs approval or if it never will show up.

@mattmia2

seems to be ok now.

It would be consistent with 2.5" iron pipe. There are two types of iron pipes, cast iron sewer pipe and schedule 40 steel pipe. Cast iron is joined with hubs, schedule 40 is threaded and joined with fittings. In cast iron 2.5" isn't a standard size, but it is in schedule 40. It's not uncommon to see them mixed in a drain system, usually what you see is schedule 40 for 2" and under, which then transitions to a 2" cast iron hub. The sizes don't exactly match but the hub system is very tolerant.

The spec sheet for schedule 40 is here:

https://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html

Did you save any of the pieces that were there?

It's worse than that. Plumbing is measured in "nominal size."

There are two main nominal size systems, IPS — iron pipe size — and CTS — copper tube size. An IPS fitting has the outside diameter of an iron pipe with an inside diameter of the nominal size — or did, when the standard was created. Since pipes are joined on the outside, the outside diameter has to be kept constant, even if new materials and manufacturing techniques mean the wall thickness has changed.

Here are the dimensions of different types of 3" nominal IPS pipe. First number is outside diameter, second is inside diameter:

Sch 40 steel 3.5 3.07

Sch 80 steel 3.5 2.90

Sch 40 PVC 3.5 3.068

Sch 80 PVC 3.5 2.90

Note that none of them have any dimension that is exactly 3" but all have the same 3.5" outer diameter.

Similarly, CTS is based on the outside diameter of a copper pipe with the nominal inner diameter. It's used for copper, PEX and CPVC.

Here are some specs for 3/4" nominal pipes of different materials:

Type K copper 0.875 0.745

Type L copper 0.875 0.785

Type M copper 0.875 0.811

CPVC 0.875 0.70

Type B PEX 0.875 0.709

Note that none of them have an inner diameter of 0.750" exactly but all have the same 0.875 outer diameter.

@DCContrarian - Good information. I've always found it crazy that CPVC uses a different sizing standard than PVC.

what i would do i pack it with oakum and that lead substitute stuff to more or less seal and support it then slip that contraption over it.

or call fernco and get the right doughnut.

I would also grind the stop out of this reducer so you can slip the pipe through and in to the hub until it more or less meets the run of the pipe.

It's a 4 x 2 ABS bushing.

Shower drains don't typically plug up do they?

I could see things getting hung up with a toilet drain or a kitchen sink especially with a disposal. Of course if someone mops the floor and uses the shower to dump the mop bucket I suppose it could plug.

Not to spoil the party I don't think MA. allows PVC or ABS in commercial buildings. But I am not a plumber and I won't tell.