Using of Wrong Electrode for Dissimilar Joint

Date 01-07-2021 11:39

Gents,

Site Construction team has made mistake and perform welding of dissimilar joint (Storage tank (A312 TP 316) to Deck of Module (Carbon steel) with wrong Electrode (E8018-G).Consequently weld has cracked. Joint configuration was a fillet weld with 8 mm leg length. Leg of tank is 55mm height. Site team is going to cut leg of tank approximately 20-30mm.

I think weld decay can cause crack of weld metal. I just want get your advise, if we will try to repair it, what is a length of need to be removed from leg of tank to get rid of from affected microstructure zone? if site team will cut from leg 20-30mm , it will be enough or not?

By 803056

Date 01-10-2021 17:36

Ouch!

First, all the weld must be removed. Citric or nitric acid can be used to ensure all the weld deposit and diluted base metal is successfully removed. That means the base metal will have to be excavated to a depth sufficient to remove all the weld and diluted base metal. Staining will indicate the diluted base metal or weld is still present.

A fluorescent dye penetrant test can be used to ensure all cracks are removed. Fluorescent dye is available in four different levels of sensitivity. If you were to use ultrahigh sensitivity penetrant, you had better plan on using fine grit abrasive to obtain a very smooth finish (polished) before applying the dye penetrant. High sensitivity fluorescent penetrant should be sufficient to detect the presence of cracks.

In any event, the Owner and his engineer should be consulted and approve the procedures used to facilitate the repair.

Best regards - Al