https://www.youtube.com/watch?v=spjoA54IQMk

When the furnace is full, sometimes the extra cobblestone can come back into the previous pipe; at other times they pop up.

Forge 10.13.2.1232
Buildcrat 6.1.5
Factorization 0.8.88.5

I restored the devices in version1.6.4, they also have this problem. It seems that If the items transporting too fast they will appear this problem. Don't know whether it's a feature.

That's not a bug. Your furnace is full so the iron pipe can't insert anything into it, and since it has nothing else to do with the items it throws them out. It was always like that, what's the point of using iron pipes there?

In this page "http://www.mod-buildcraft.com/wiki/doku.php?id=bc-4.2:diamond_transport_pipe", it mention that "Unlike with iron pipes, items in diamond pipes do not bounce back."
That is to say, the iron pipe can make items go back to previous pipe if the inventory it connected is full. I think it's an important feature. Using it I don't worry about items going out of pipes.

Correction: The occurrence condition is not "transporting too fast"; It's "when items in pipe is too dense".

@sfchipan no that simply means that if the output direction of an iron pipe is the same as as where the item came from the item will go that direction, with an diamond pipe that is not the case

What you are describing is what a normal pipe would do (I think, haven't really played since 1.2.4 so I don't remember how normal pipes behaved, but it definitely isn't like that in iron pipes, like AE said what you read is for items entering through the exit)...

Thanks for correcting me. It looks like I misunderstand the wiki.
But the iron pipe acturally has some feature like I said. I upload a video again.
https://www.youtube.com/watch?v=mbfo-PDAfZI
This time the items in pipe is not dense as in first video so almost all extra items gone back into chest when I used iron pipe (instead of diamond pipe and gold pipe).

@sfchipan is correct and the same applies to the Daizuli pipe. I have used it a lot in different builds.

But it is also as @sfchipan discovered not a complete feature. It was an effect of the changes to all pipes in 3.2. It was not intentional that the Iron pipe would work like that so it was never fixed to work in all cases. The Iron pipe will still drop items if they come in stacks or to close to one another.

It is a very nice feature I think we should implement fully. It would be a form of basic insertion pipe.

@SandGrainOne Hoping this feature can be retained and improved.

Marked off for implementation in BC 6.2.0. Also, I'm glad you're back, @SandGrainOne!

Still just simply lurking.

The requested behaviour has been implemented for the most part as the clay pipes.

It's actually a bug with a transport pipe not force-updating the tile entity if it was invalidated and then revalidated during the movement of the item, which generally only happened with vanilla furnaces.