VICTAULIC COUPLINGS FOR SUPER DUPLEX PIPING SYSTEMS AT 65 BARS

[Salmet]

Dear Members,

I am being asked to install Victaulic coupling joints at 6inches diameter super duplex stainless steel piping system for untreated sea water, in a Reverse Osmosis water treatment plant, operating at 65 BARS (943 Psi). Grooves are supposed to be machined on the piping components for the installation of gaskets. Does ASME B31.3 allow us to use these type of joints at such high pressure and Does the code allow machining for mechanical joints.

Thanks in Advance.

 

[LittleInch]

B31.3 allows grooves and threaded pipe and treats it in the same way.

See 304.1.1 for how the min thickness is t + c, where c is the groove depth plus other tolerances.

I think you'll find the grooves are for mechanical strength to stop the pipes coming apart, not a gasket.

That will make your Super Duplex pipe quite a lot thicker and cost a small fortune. basically I think you're looking at another 2.5mm wall thickness for the 6" groove.

What's wrong with welding it?

Use of the joints is up to you. B31.3 doesn't make any judgement on this as far as I know.

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

 

[MJCronin]

Agree with LittleInch..

Your choice of Victaulic coupling joints on a super duplex piping system will make this a very expensive system.

(By super duplex, I assume that you mean UNS32750/UNS32760 such as AVESTA SuperDuplex Stainless Steel also called Alloy 2507)

What is the problem with all welded piping and flanges where they are absolutely required ?

Did you explore a Schedule 80 carbon steel system with a galvanized coating for your raw seawater ?

I believe that this would enable you to have your desired Victaulic coupling joints at a reasonable cost.



MJCronin
Sr. Process Engineer

 

[KevinNZ]

Victaulic have design guide for B31.3

https://www.victaulic.com/assets/uploads/literature/26.11.pdf

 

[EdStainless]

And then there will be all of the crevices formed with the gaskets. Welding these alloys isn't easy, but can be done with very little loss of corrosion resistance when done correctly.
I have seen welded piping systems with heavy stubs and mechanical clamps joining major sections. This allows for ease of fabrication, transport, and assembly. And all of welds can be done in a highly controlled shop environment.

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P.E. Metallurgy, consulting work welcomed

 

[TBP]

If you roll-groove pipe - don't take any metal away - you can still count the pipe as full-wall. Is it even possible to roll-groove this material? I don't know.

My recollection is that Victaulic systems at least used to be not rated for anything close to the pressures you're looking at.

At the very least, this sound hideously expensive.

 

[EdStainless]

My hunch (I didn't run the numbers) is that this is sch40 pipe in superduplex.
I don't think that you can roll a groove in this material at that thickness, and I doubt that the rolled groove style fittings will work at these pressures.

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P.E. Metallurgy, consulting work welcomed

 

[LittleInch]

Well the OP hasn't logged on since Tuesday and isn't prolific with response to his own questions....

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

 

[MJCronin]

EdStainless....

Agreed ..... A machined groove like the OP wants on schedule 40S, 6"NPS pipe will leave almost no pipe wall left

Flexitalic offers a variety of coupling styles with different maximum pressure ratings ...

According to this published chart, only ONE STYLE BARELY MEETS the clients high pressure requirements.

https://www.victaulic.com/assets/uploads/literature/06.01.pdf

He may be forced into a Schedule 80S piping system ..... at huge cost

Time to rethink his choices ....

MJCronin
Sr. Process Engineer

 

[MJCronin]

Thank goodness that the OP has been respectful and has not left everyone hanging..

It is considered reasonable and respectful to complete the thread on this forum and then tell everyone of your final choice

It is also considered polite to say please and thank you to people who go out of their way to help you ....

But many of those western customs and rules do not apply to the mid-east ...

Get what you want from others ... then screw-'em

MJCronin
Sr. Process Engineer

 

[LittleInch]

Last log in 8th June.... Maybe he's gone on holiday.


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

 

[MJCronin]

....or couldn't care less



MJCronin
Sr. Process Engineer