Recomended spacing between ODs of pipes/tubes in an array 1

[BasakAbhishek]

Hello,

I have to design a 2D array of tubes, where each tube is to be butt welded to corresponding stubs (also arranged in an array). I plan to weld the tubes row-wise. Hence, there will be access from one side only. Is there any guidelines regarding the minimum gap between the ODs of adjacent tubes? If not, what do you recommend?

Regards,
Abhishek Basak

 

[LittleInch]

It's usually the OD of the largest tube as the edge to edge spacing , but you probably need min 300mm. These are MINIMUM sizes.

You will need access from top and bottom to weld all the way around. Or are you building in sequence so going from left to right?

Really need to ask your friendly welding engineer what's feasible in your particular location, pipe size, wall thickness, need for NDT etc

Sketch, sizes, wall thickness, type of welding all make a difference to the reply.

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

 

[EdStainless]

In high purity applications where they use orbital welding units the clearance is dictated by the welding equipment.
They presume that they may have to cut and reweld any line at any time.
Yes this is a lot of space, but it saves millions of dollars later.

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P.E. Metallurgy, consulting work welcomed

 

[BasakAbhishek]

Thanks EdStainless and LittleInch .... 300 mm is quite large for my use, but using standard open welding heads a gap of 96 mm is workable for me.. In my case each of the welds will be radiographed once each weld is done, one at a time. Also, the media is non-aggressive, so it should be ok...thanks anyway!
Abhishek

 

[LittleInch]

Remember you also usually need a grinding disc in between passes...

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

 

[XL83NL]

How about ATEX requirement, or good design practices from a leakage/explosion point of view?

Huub
- You never get what you expect, you only get what you inspect.

 

[r6155]

Also consider NDE

Regards

 

[LittleInch]

Atex and similar normally don't regard welded pipes as creating a hazardous atmosphere.

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

 

[XL83NL]

Correct. I was thinking for a flange point of view, but just noticed that's not in the OP's question.

Huub
- You never get what you expect, you only get what you inspect.

 

[BasakAbhishek]

Hello...no there is no flange to speak of..there is no explosive environment..it is 8mm thick so should be weldable in a single pass, else I am open to reducing the thickness to 6 mm...after each weld is finished it will be subjected to 100% radiography before moving on to the next tube...hope these clarifies the issues raised.
Abhishek

 

[LittleInch]

What pipe size are we talking here?

Is the gap fixed by something or can you weld and then move or roll into place?

Do you need welded pipe?
Do you need steel pipe?
Could you use reeled pipe?

But 96mm is too small for me.....

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

 

[BasakAbhishek]

Q-What pipe size are we talking here?
A- Its 170 mm ID, Thickness: 8mm

Q-Do you need welded pipe?
A-No it will be a seamless tube

Q-Do you need steel pipe?
A-Steel (2.25Cr-1Mo) is from process and cost consideration

Q-Could you use reeled pipe?
A-No its straight lengths..not reeled

Q-Is the gap fixed by something or can you weld and then move or roll into place?
A-Its basically a PV head with many nozzles onto which the tubes have to be welded..so the positions are predefined

 

[LittleInch]

Ok,

That's a very odd size pipe!

What I meant was do you need to weld the pipes or do some other form of jointing....
If the head is fixed do you have any leeway?


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