As far as interpass temp is concerned ....if you speaking of a 75mm
plate ...or more than 50mm.Interpass temp shall be measured on the
weld metal or immidiately adjacent to that heat being focused....allow
2minutes for every 25mm..then you good to go........
Go to your WPS and you will see interpass temp which is given in KJ
ON another note preheat ranges from 50 -250 degrees celcius
Interpass temp is measured in KJ so work out your HI and AE
On Thu, Feb 16, 2012 at 1:37 AM, DEBASISH <debasish.uae@gmail.com> wrote:
> Dear
> Interpass means temperature (3" on either side of joint) inbtween two
> consecutive passes. And in this case if it is left after laying Root &
> Hotpass all through out the shit/night, then you tell me where is the
> essence of the word interpass.-Unless otherwise it has ben kept under the
> preheat you mentioned all through out the break.
>
> As far as my knowledge goes, there is no code reference about this GEP(Good
> engineering practice). Basically this is a truely a welding-metallurgical
> aspect and if the joints are so critical, then your QC has right to say so.
> Actually what happens: With only two passes laid on this XXS heavy wall
> thickness parent metal, the weld deposit thickness is not that much to
> withstand the contractional forces exerted by the parent metal from both
> side of the joint. Thereby resulting huge stress build up which leads to
> cracks. In heavy walled plates as well as pipes, longitudinal ( cold cracks
> / HIC ) on the bead laid yesterday are often seen in this partially welded
> items.
>
> Way forward: May be at the best if you can put a deviation note and convince
> yourself as well the QC that it will be 100% NDT done before proceeding
> further. 100% LPI & 100% MPI on all such partially welded joints. And
> marking these joints with a distint identification no. and doing 100% RT of
> all these particular joints after final weld completion., even if the drg
> says % RT on all finished joints.
>
> regards,
> Debasish
> Dubai.
> +971504349936
>
>
>
> On Wed, Feb 15, 2012 at 5:07 PM, jesti fer <jesti_fer@yahoo.com> wrote:
>>
>> Dear experts,
>> I need your help, In our project (B.31.3) CS pipe joints ASTM A106 Gr.B 8"
>> Sch XXS, our construction team kept the joints after root pass and hot pass
>> welding, but our QC instructed to cut and and re-weld the joints. Really it
>> is required and it is mentioned any were in code? We are maintaining
>> preheat at 150-Deg and inter pass temp 300-Deg
>> Please help me;;;;
>>
>>
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>
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