Pipe Connection - different materials and sizes 2

[RReal2024]

Hi! I am new to the forum and a new civil engineer.

Question: what would be the best way to connect the three pipe sections?
I just designed a system where 3 different pipe sections are used:
[ol 1]
[li]HDPE (IPS) 8 inch DR 9, O.D. 8.506 [/li]
[li]Carbon Steel 6 inch STD schedule (cement mortar coated), O.D. 8.126[/li]
[li]HDPE (IPS) 5 inch DR 9, O.D. 5.486[/li]
[/ol]

Currently I am proposing flanged reducers. Would a Victaulic Style 904 Flange Adapter work (at least for section 1 and 2)? I tried to call their number but no one responds.

Thanks a lot!

 

[bimr]

Above grade or below grade?

What is the application?

 

[LittleInch]

Pressure?
Any axial thrust or force?
Item 2 is this the OD of the mortar outer coating?

Can't you just add on a 5 inch to 8 inch PE reducer then have the same connection onto the 6 inch steel? Pipe?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RReal2024]

Thank you so much for the replies!

The three sections make a (temporary) siphon. The upstream half of section 1 will be in the reservoir, and the second half of section 1 will be above grade if there is no flooding. Pipe section 2 and 3 will be above grade if there is no flooding.

Pressure varies throughout the siphon, but for section 2 and 3, the pressure will go down to negative (but above vapor pressure) then slowly reach 0 at the outlet of the siphon. That being said, the pipes do not need to handle too much pressure.

The second section's OD accounts for the mortar coating.

To LittleInch: Yes currently I am proposing DI flanged reducers. So the first reducer will be 8 to 6 inch. The second reducer will be 8 to 5 inch. It's my first time working with *actual real world* piping, so I would really appreciate your corrections if I understood anything incorrectly.

 

[LittleInch]

I would just make up some neoprene type flexible connectors and use a couple of large jubilee clips.

But it's good you recognise that PE pipe isn't the same OD as steel, but you never normally allow for the concrete coating when joining pipes.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[coloeng]

What is the purpose of the steel pipe. If it is to allow for a tap on the line you could just use a tap saddle compatible with the HDPE pipe.

 

[RReal2024]

Thank you for the replies. I find the Flexible connectors really interesting, will definitely look into that! Unfortunately I don't think a tap saddle is preferred, but thanks for the idea, coloeng! I've learned something new.