stainless pipework underground 1

[eski1]

Hi
we are planning to put a 14" sch 10 x 42m long pipe underground , it will be waste water going thru this to an effulent plant under gravity feed . my question is what type of welding join should we do , at present we are thinking of doing a butt weld full penetration & then weld a band over the top of this for extra strength. This would be to stop any potential future ground movement causing cracks in the weld etc . does anyone know the correct procedure
thanks in advance
chris

 

[cvg]

post this in the Waste disposal & treatment forum for better analysis by the sewer experts...

 

[MJCronin]

eski...

What type of joint/fitting systems are offered by the piping vendor ?

How about a "bell & spigot" joint system ?

Hope that there are no chlorides in the soil......


_MJC

 

[Zapster]

Is there a reason why cement or ductile iron pipe will not work? What is in the waste water where typical pipe materials will not provide adequate service?

If you do a full penetration butt weld, why do you think your weld factor will be less than one? What alloy are you planning to use and what code are you using for design compliance?

 

[eski1]

Hi
Thanks for the reply's so far , i have some answers and more info on the job :-


304L Stainless was chosen by our customer so would assume they have done this for good reason .

The product going thru the pipe is 100 degree c C.I.P wash from a food production tank so it will be diluted caustic & nitric acid this won't be a constant flow , only every half hour when tank clean is required .

The pipe will be burried about 1250mm underground with pea gravel back filled ontop then a road surface ontop . There will be lorry's travelling over this on a day to day basics .

As far as joining the pipe we are looking purge weld most joints ,and also flange a couple where required on these what gasket material would you recommend ?

With regards any chlorides in the soil i must admit not knowing the answer to this but i will look into this as i assume it would eat away the stainless steel .

hope this helps

best regards chris

 

[LUDPEKA1]

OP "my question is what type of welding join should we do , at present we are thinking of doing a butt weld full penetration & then weld a band over the top of this for extra strength."


Butt weld I would think but I have not seen a band ever added in this type of application.

I would think the most important thing is proper installation of the pipe. Starting soil conditions, pipe bedding, soil compaction in lifts as the trench is backfilled, etc… I have not worked with 14” sch10 S.S. pipe in underground applications, but if you have strength concerns you could look into using a higher sch or I would also give some thought to a pipe sleeve especially for any part of the line that might see vehicle traffic.

 

[europipe]

You should protect the complete pipe with a coating tape.
That prevents affecting it with p.e. chlorides.

Greetings