Mr. Alikan,
If you are referring to cross country pipe line welding done using clamps for fit up, then you should know that, the total length of such lines runs into
hundreds of kms and with more than a km length welding per a day. It will not be practical to tack weld it initially, then complete the joint using stringer
welders.
The clamps also give proper fit up, in a short time comparatively and avoid cracking during root pass welding. Tack welds will not have sufficient strength
to hold the lengthy pipes together. Further, it is a low pressure flow line, the quality check through radiography is just 10% or so except at crossings.
Clamps are removed immediately after 50% of the weld is completed and re put on next joint before welders complete the earlier joint. It helps to save
fit up time also .
On the other hand, plant piping is a pressure line, requires a proper fit up to to pass 100% radiographic quality. Hence clamps are not used and done by
cleats and tack welding to hold the edges together till the completion of weld. The space available in the racks are so less, clamps may not suit the area.
Sridhar.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
From: Akbar L <akbarjrr@gmail.com>
To: materials-welding@googlegroups.com
Sent: Friday, 26 October 2012 8:36 PM
Subject: Re: [MW:15776] Why do we Use of clamps instead of TackWelds in pipeline?
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If you are referring to cross country pipe line welding done using clamps for fit up, then you should know that, the total length of such lines runs into
hundreds of kms and with more than a km length welding per a day. It will not be practical to tack weld it initially, then complete the joint using stringer
welders.
The clamps also give proper fit up, in a short time comparatively and avoid cracking during root pass welding. Tack welds will not have sufficient strength
to hold the lengthy pipes together. Further, it is a low pressure flow line, the quality check through radiography is just 10% or so except at crossings.
Clamps are removed immediately after 50% of the weld is completed and re put on next joint before welders complete the earlier joint. It helps to save
fit up time also .
On the other hand, plant piping is a pressure line, requires a proper fit up to to pass 100% radiographic quality. Hence clamps are not used and done by
cleats and tack welding to hold the edges together till the completion of weld. The space available in the racks are so less, clamps may not suit the area.
Sridhar.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
From: Akbar L <akbarjrr@gmail.com>
To: materials-welding@googlegroups.com
Sent: Friday, 26 October 2012 8:36 PM
Subject: Re: [MW:15776] Why do we Use of clamps instead of TackWelds in pipeline?
Dear Gents,
The Purpose of Clamp is to Maintain the Pipe alignment and rigidity to awoid the crack form in during initial welding.
in pipeline welding it is dangerous/shouldnot maintain fit-up like piping so that weld to be completed atleast one thied of thickness of pipewall.
Regards,
Alikan.
On Fri, Oct 26, 2012 at 11:31 AM, srinivas rao <ksrvasu@gmail.com> wrote:
Dear Gents,Can anyone clarify Why can't we use tack weld for fit-up in pipeline?RegardsSrinivas--
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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