Advantage of Internal & External Clamps

[mohd]

Dear experts

what are advatages and disadvantages of using external clamps&
Internal clamps in Pipeline.

We'r doing 30"pipe line projects and client insist us to use only
Internal clamps for fitup pupose.

regards,
mohd

[eccospi]

Dear Colleague.,

Regarding the use of internal clamp or jigs if it is possible is preferable
for the following reasons:

1. the internal clamp/ jigs give true smoother alignment for both joint
ends leads to better weld root.
2. the internal clamp/jigs use the pushing technique which reduce all
other additional temporary fitting tack welds.
3. higher in production and better quality fitting.

Hope this will cover your query.
Your colleague
D.eng.A.Aziz Gendia
Ecco-spi President & CEO

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[manpreet]

On Mon, 18 Jun 2012 11:24:53 +0530 wrote
>Dear experts

Hi,

External Clamps are allowed only for Tie-In joints or for short pipelines ans small diameter (<6 in.)

At least 50% of root pass is to be completed before the external clamp is released,
Internal alignment clamps are preferred for better alignment and not released until 100% of the root pass is complete.

Misalignment between the internal surfaces shall not exceed the lesser of 3mm or 1% of the pipe internal diameter at any point, more restrictions are set for Pipelines subject to strain.


Regards,
Manpreet Singh

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[Mohamad Shah Gubah ahmad]

internal clamp or chim more easy to install from internal because during fit up prosess both side of pipe are effected compare to external clamp.

[Phanikumar Atluri]

Dear Mohd,

The Advantages are:

01.Can avoid tacking on the parent metal outside the joint which will save damages to base metal, reduces the rework required.
02.Accurate alignment.

But there may be some restrictions also there with the clamps .i.e it may not be capable to  use in the lengthy jobs / Heavy wall pipes .

With Best regards

Phani kumar