RE: Dimensioned Isometrics

From: <B.Sivasubramanian>
Date: Sat Apr 16 2005 - 00:02:00 EDT

Dear Paul,

1. Yes. The Weld Joints can be left over night provided if the Root Run and Hot Pass is completed. However when you restart you need to preheat the joints atleast to 100 Deg C. Also the weld joints are to buffed
2. But general practice is to employ more than one welder in such joints. We have sometimes 4 welders working on a single joint.
3. I would recommend use of semi / fully automated welding process in such cases. However the number of weld joints shall decide the economics.
4. Yes in places like Kazakh, where the ambient temperatures are sub zero all these norms go for a sixer.

Cheers

Siva

-----Original Message-----
From: Paul Bowers [mailto:pbowers@pipingdesign.com] Sent: Friday, April 15, 2005 9:50 AM
To: <a href="/group/PipingDesign/post?postID=F4Rmcycod35a35flSbphdAFpBZ2mqDpCBwAWiHtd8wwkUzkHIHsAbWgMYxmeIPaQq1wTMApvRF9mJQ8nleqC46F3gg">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] Dimensioned Isometrics

Thanks, Siva.

I assume that means (generally, since there are the other factors you mentioned that can vary) that butt welds over 20" diameter require multiple shifts. Can a partially-completed butt weld be left "overnight" and be continued the next day?

I'm referring to field welding, common Sch. 40 carbon steel.

Interesting that you mention climatic conditions. Some facilities have ambient construction temperatures that are lower than the usual -20 degrees F.

Paul

B.Sivasubramanian wrote:
>
> Dear Paul,
>
> The productivity of the Welds in Piping Works is a subject it self. The
production rate depends on the following factors
>
> 1) Whether the Weld is done in Fab Shop or Field
> 2) If in field whether it is Unit Piping or on Racks or on Pipes
> 3) MOC
> 4) Thickness of the Pipes (Schedule)
> 5) Pre weld / Post Weld heat treatment requirements
> 6) Welder's skill
> 7) Electrode Diameter used
> 8) Current used for Welding
> 9) Type of Welding Process (Manual / Semi Automatic / Orbittal etc)
> 10) Climatic Conditions
>
> etc.
>
> Just to give a guideline, if the work is in a typical hydrocarbon facility on
an average (say in a plant where the total quantum of works is 400,000 ID) you may consider 20Inch Dia per Welder Day ( 1 Welder Day = 8 hours of Work)

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