Repair a hole on pipe by welding

[Pruk]

Hi All,
I'm Pruk.

Do anyone have ideas about how to repair a hole on pipe?

I have a job to fill a 3/8" hole on a 16" Sch 160 pipe with A106 Gr B material. Inside surface of the pipe need to be very flat and obstacle is not allowed. I'm thinking to weld it as per attached picture. If you have any ideas, please feel free to share.

 

[deco0404]

Hi Pruk,

I'm not sure I would recommend this. I'm assuming the fact that you are using sch160 pipe is because of high pressure, temperature, erosion problems or a combination of any or all of these. The problem with welding something like this is that it is very difficult to get adequate fusion to the wall of the pipe, this in turn will leave a considerable discontinuity within the material. If erosion is a consideration it will be impossible to get the weld flat, you will end up with excessive material on the inside surface which will disrupt flow, or the internal surface will be concave again this can disrupt flow.

If you can give some more details of the service conditions, I may be able to offer better advice

Declan

 

[MikeHalloran]

Have you seen the T-section consumable inserts that are used to make butt welds in pipe, working entirely from the outside?

I'm thinking you might be able to make a ring like that, bent the hard way to 3/8" diameter (or just machined from the solid) and use it to weld in a plug, of say, 5/16" diameter.



Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

What's the pressure, temperature, fluid inside the pipe, condition of the pipe, length of time until you can make a proper repair, criticality/criminality of the repair (what is worst case IF (when ?) your repair fails?

If NONE of the aove are limiting, and IF you (your company) can tolerate the risk, then consider an outside "wrap-around" coverplate, rather than a side weld into a "dirty" pipe you cannot clean and prep for welding. Since you can clean and weld prep a cover plate over the broken hole, then you can (better) control the weld covering the boundary of the failure. (Rather than trying to assuming you weld directly and blindly - but successfully!) into the (unknown) edges of a KNOWN failure.)

Also, just because you can see one obvious failure through the pipe in one location, doesn't it seem reasonable (prudent) to suspect that this one failure might be bigger (lobger on the inside) than it appears on the outside?

Isn't it logical to suspect that one break all the way through the pipe in one area indicates multiple "almost" failures in (many) other areas? Get a reliable expert to do a "pig test" scanning the pipe for wall thickness.

 

[rneill]

I've never seen anything like this done before. I would remove and replace the section of pipe (cut out a cylinder and install a new pup piece). Alternatively, perhaps you could consider a full encirclement sleeve, a composite wrap (e.g., Clock Spring), or a clamp type fitting (e.g., PLIDCO).

Depending on where this pipe is installed and which design code applies, there may be regulatory requirements with regards to the acceptability of different repair methods and you may require pre-approval on the proposed repair method.

You might want to look at API 1160 or 2200 as these do provide some information on methods or repairing pipeline piping. There's another good resource on the UK Health and Safety Executive website as well ...

http://www.hse.gov.uk/research/otohtm/2001/oto01038.htm

 

[acad96]

My idea cut and addition pipe shot piece replace coupling.

 

[Pruk]

Hi All,

Actually, this pipe is a part of orifice meter.
At first, I've try to order the new spool but seems like roundness of normal pipe is exceed acceptable error.
Normally, if I'd like to have a pipe with schedule 120, I'll order pipe with schedule 140 or 160 and then hone it to ensure its roundness but this time I need pipe with schedule 160, so I can't find a pipe with more thickness. The manufacturer which I normally order the whole orifice meter will not work on this very short spool. That why I'm finding the way to fill this hole.

After welding, I already have a method to furnish inside surface.

Please find more details for service condition.
Operating pressure = 1800 psig
Operating temperature = 120 F
Service fluid is natural gas with 22% of CO2 and 0.003% of H2S.

 

[racookpe1978]

How long?

Can you select a different metal type and machine the missing "pipe" on a simple lathe from stock?

 

[BigInch]

If you need that schedule for pressure, you'd better be thinking about cutting it out and replacing a complete segment.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

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