Re: [MW:12653] Orbital Welding - weld joint preparation

Dear Friends,

I agree with Mr.Pradip Goswami, actually this depends upon the type of service/application,

and type of welding process, materials used. U, V J grooves with no root gap, GTAW process used in Oil & Gas projects. if its a Tank, Crosscountry Pipiline are using the with little root gap FCAW, GMAW process.

Thanks & Regards

Amit Pahuja

Sr. Welding Engineer

On Tue, Oct 11, 2011 at 5:46 AM, pgoswami <pgoswami@quickclic.net> wrote:

Hi Jignesh,

J -groove preparation is generally the standard for WEP for orbital welding in the industry. The rationales are as follows:-

Orbital welding is a precision welding technique,As this is a mechanized welding , there are not much scope for welder manipulation.

Single Vee (typically thermally cut and later ground) would not be as accurate as a machined weld. Hence any mismatch of root face and root gap could affect the quality of orbital welds. Where as machined beveled J -Prep would be more accurate and less chances of errors.

Orbital welds are preferred for high weld integrity (quality wise), hence any incremental cost due machining may be negligible considering investment on the machine and less rejection and repair rates.

Lastly fabricators could save on significant volume of weld metal.For expensive materials e.g stainless and non ferrous this reduces the overall cost of fabrication..

Considering all the above factors, the default industry practices are the J-prep.Some shops may have preferences to single vee or compound vee type welds.However one the available tooling are available a change from Vee to J-prep would not be difficult at all.

Please seethe extract from a book of Fronious which explains this issue very clearly.

Thanks.

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

On Mon, Oct 10, 2011 at 12:06 PM, Desai Jignesh (Mumbai - Piping) <J.J.Desai@ticb.com> wrote:

Is it mandatory to make 'J' groove preparation for welding of Piping joints by ORBITAL Welding?

Regds/Jignesh

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