joining seamless pipes 1

[trish129]

The very thought of having a joint in seamless pipes seems absurd but what if the required length of seamless pipe is not available and the only option is to join two pipe pieces such that the joint sustains a particular operating pressure.?is welding recommended in this case?

 

[BigInch]

Sounds like a reasonable solution.

 

[trish129]

is it an established method? any examples and cited evidences?

 

[LittleInch]

Errr, what size and type of pipe are you thinking of? In pipelines pipe comes in 12m or 6m lengths so you need to weld them together to form any pipeline longer than this.

I have a feeling you mean small bore tubing??

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

 

[trish129]

3/4 dia seamless pipes.7m each..

 

[BigInch]

Maybe you could thread and couple as well.

 

[1gibson]

3/4" seamless pipe is not available longer than 0.7m (~2.3 ft) ? You might want to double check that.

 

[Gator]

Sounds to me like there's a fundamental misunderstanding in the OP.

Piping Design Central

 

[MickMc]

Pipes are normally supplied in either single random length or double random length which are circa 6m & 12m respectively or can be specified cuttings from these lengths at extra cost with smaller bores in the SRL for handling purposes with lengths I expect being standardised for handling and transporting. The joint will be to type specified in your piping service class which may be threaded, socketweld or buttweld with typically NPS 2 and over buttweld. Typically threaded piping is only used in utility systems and is joined by threaded couplings in straight lengths and threaded elbows, tees etc in change of direction with socketwelds being similar except for type of joint but are also used in hydrocarbon services depending on client. Again buttwelds have similar fittings for change in direction with obvious different joint type but straight lengths of pipes directly welded with no couplings.

 

[LittleInch]

trish 129.

apart from the fact you shouldn't double post the key item is your phrase "The very thought of having a joint in seamless pipes seems absurd " Why do you think it is absurd?

All pipe needs to be joined to something else at some point otherwise it is just an empty tube. If you explain this we might be able to see where you are coming from.

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

 

[pennpiper]

trish129
Welding of pipe is really very common. Look here:

https://www.google.com/search?q=ima...i=XJdCVYuHHviKsQSFyYHgCw&ved=0CB0QsAQ#imgrc=_

Sometimes its possible to do all the right things and still get bad results

 

[bimr]

A certified welder can easily fabricate the required pipe segments using TIG welding processes with purge which meet all ANSI and AWS requirements.

At some point, all pipes have to be joined together.

 

[trish129]

thank you all for your replies..

let me lay down the specifics of my problem...

Operating conditions: water for jet washing at normal temperature and a operation duration of 14 hours subjected to a working pressure of 260 bar
Seamless pipe material: ASTM A 106 Grade B
Pipe schedule: 160
¾” (the nominal pipe size)

Important consideration:1) this pipe travels horizontally between circular supports/guides.so the weld beads should be flush with the outer surface of the pipe so as to avoid interference/jamming with the circular guides.

2)alignment..the tolerances and alignment issues are of paramount importance because any mis-alignment would inhibit smooth travel through the circular supports

circumferential butt welding of seamless pipes must be somewhat different from butt welding of welded pipes .what weld procedure should be adopted? What are the considerations for butt weld specific for seamless pipes like proper selection of filler metal

what would be the testing plan for the welded joint to ensure integrity at such operating pressures?what should be the possible configuration of test samples?

 

[Gator]

At these pressures and the level of details being asked I'm going to recommend consulting a local piping engineer.

Piping Design Central

 

[bimr]

You should be using stainless steel so that you would not have to worry about corrosion at the support guides.

Use an TIG oribital welder with gas purge.

Don't think it is a question about how to do this. The problem that you have will be to find a good shop close to your business.

 

[bimr]

Here is a picture of the results.

 

[trish129]

stainless steel for what?

can i have videos demonstrating welding of seamless pipes..?

there must be some laid down procedures/standards for circumferential butt welding of seamless pipes..where can i find them?..

and after that how do i test them..the operating time is about 14 hours...how do i plan the testing of this joint?

 

[bimr]

If you use stainless pipe, you don't have to worry about corrosion.

Check youtube for video.

https://www.youtube.com/watch?v=-w7qQ2V8jkY

Do a hydrostatic test on your entire fabricated pipe segment.

http://www.eng-tips.com/viewthread.cfm?qid=385722