ABS pipe connection question

Question

When installing a new tub, I need to move the drain about 3/4 inch. My current plan is to just add a reducer to the exposed pipe and then the p-trap. I have two concerns that I was hoping to get some thoughts on.

I notice when joining certain pieces there is an inevitable notch in the flow of the tube, if I use too many connections like this in a short space does that create a problem?

The exposed pipe is slightly larger than 1/2" while the connector would allow for about 3/4", is that not enough exposed pipe to create a secure connection?

Thank you

Answer 1

You need a thing called a "socket saver", which will drill out the pipe stub from the fitting hub, allowing you to glue in a new section of pipe the right length - otherwise you need to cut out and replace fittings to get a new hub in the right location to glue to, and pretty soon the cost of a weird tool you won't use often is less than the cost of all those fittings and the work related to installing them.

You MIGHT find one for rent at your local tool rental - might not, but it's free to ask them, and generally cheaper to rent for something you might never use again. Alternatively, you can hire a plumber to come use their's, but given typical plumber rates, that might not be a savings.

Answer 2

If you are putting that extension in so the flow is from right to left on your hand-drawn diagram then that is correct.

Having the flow left to right is not the way the seals on that type of pipe connector should be used.

For the piece of exposed pipe, that is not sufficiently long to make a secure leakproof connection. You will need to find a way to extend that.

If all those joints are glued then I would get a piece of straight pipe about 2" long and another piece about 4" long. Cut a slit lengthwise in the 4" piece such that it can be compressed and it will slide into the exposed pipe as far as possible. Using the pope cement, glue it into place. Then slide the 2" piece onto what is now sticking out and glue that. Once dry trim the end as needed.