Minor Cracks in SAW Welds Cap

[Gowtham Rajendran]

Dear All,

In the cap pass of the SAW Welding, we have observed some minor cracks while performing MPI as you can find in the attached pics.

With pipes welded with the same parameters and almost the same condition, we are finding this kind of defect in some pipes, if anyone has come across such kind of defects, kindly share your experience and possible root cause.

Thanks in advance for your valuable inputs.

[Raghuram Bathula]

You must specifying max possible details such as MOC, consumables, preheat, post heat, thickness, code of construction  etc??

[Rishikesh Kumar]

Can your share more information  like material, consumable, welding process and sequence, heat input,etc . then anybody might help in right direction...

--
https://materials-welding.blogspot.com/
https://www.linkedin.com/groups/122787
---
You received this message because you are subscribed to the Google Groups "Materials & Welding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to materials-weld...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CABLAf1L-TDhOLG1vDXgLLrvZOA2wW3dj-gqwk6dLTvhAdM%3DRuA%40mail.gmail.com.

[Gowtham Rajendran]

Mr.Rishikesh Kumar &  Raghuram Bathula,

Material - S355ML

Thickness - 40 mm  

Consumable - F7A8-EM12K

Process - SAW ( Tandem)

Heat Input - 3.15 Kj/mm

Preheat - Not applicable

Post heat - Not applicable

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CAEXs1Ko%3D0OAR353SM%3DPic5sgpvT8cFHzVhq3Fw3-mkBSE_SZjw%40mail.gmail.com.

[Mindaugas]

Hello Gowtham Rajendran

You should try to preheat metal to min 75C deg. Because you're parameter very high and metal have to stress during welding and after welding it cooling.
Second question: could you show How are located welding seams on  construction.

[Rishikesh Kumar]

 the information provided is still very limited. however based on the provided details  , my observation is as per below:

1. Flux quality is not good. Further ( not proper preheating, preheating maintenance, recycling of flux ratio is not proper, cold flux with  mixture of foreign materials).

2.The  crack pattern seams crater cracks. this type of crack are developed due to  various reasons- mostly due to foreign metallic material entrapment. like: copper entrapment ( needed to check coated copper of wire ( in the form of powder) are mixing on  continual interval or not) ,

3. The Heat Input is very high . needed to  reduce if feasible.

4. Width to depth ratio is not proper( need to review micro-structure of crack section) 

5. Check presence of any foreign material at crack region through micro-structure 

6. Check for solidification pattern at crack region ( if solidification issue found than change the current and voltage  accordingly   to ensure  W/D ratio within acceptance range)

7. Since thickness is around 40mm and its capping run issue, so adequate preheating of 50-100 deg C might be maintained during welding. further  preheating might not be resolve this issue 

Check as per above and inform any progress

Regards

Rishikesh kumar

 

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CABLAf1LNmmwYMZG-CDejZ6Ni5h-p-zfgFczeGKXz%2Bsy%2B0s0hCg%40mail.gmail.com.

[pablo.cartag...@gmail.com]

Dear Friend,

So they aren't a continuos, regular defecrs & the appearance of defects are various and very superficial .
I bet it is a mechanical cause.

It is a slight variation in the height of the wire against the wall of pipe during welding caused for ocasionaly ,scraps, small particles, rests of flux or other solids that suddenly are in the base of the trolley that translates the pipes making different the above height.

These aren't the typical pock marks caused for a low ratio of recycled flux in SAW manufactured pipes.

I hope it helps