Tack Weld Requirements – Danger

Are you working with high-strength steels? Or critical components?

SFS-EN 1090-2:2018: 7 WELDING. Arc welding of ferritic steels and stainless steels shall be in accordance with the requirements and recommendations of EN 1011-1, EN 1011-2 and EN 1011-3 as relevant.

The SFS-EN 1011-2 standard, Chapter 13 says:
"Tack welds
It is recommended that the minimum length of a tack weld should be 50 mm, but for material thicknesses less than 12 mm the minimum length of a tack weld shall be four times the thicker part. For materials of thickness greater than 50 mm or of yield strength over 500 N/mm2 consideration should be given to increasing the length and size of tack welds, which may involve the use of a two run technique. Consideration should also be given to the use of lower strength and/or higher ductility consumables when welding higher alloy steel."

Okay, but why, it's very uncomfortable to join heavy pieces without small tack welds first. In Finland we call those "hinge weld".

"Stop making those, small tack welds may cause cracks", they said..
A visual test + penetration test before welding may sound great, but here’s a hint:

It’s not enough.

The crack may form DURING welding, but what if no one hear bang or see when it forms? CHECK THE VIDEO!

Did you spot it?

If there is no UT inspection, cracks can stay hidden under the weld until we finally see them and then we have a big problem, or even a serious danger.
This video clearly shows how heat, high strength steel, and too tiny tack weld together can be dangerous combination.

More information and details have been documented with ArcLess Academy -team, but in this post the point is to understand your own process and risks.

Please share this post if you know anyone who is working with high-strength steels.

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Cavitar Ltd. ArcLess Academy & hashtag#ArcLessVision makes visible what has previously only been talked about.