Seeking help: Issue with cracking of the clad weld at the manhole
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On site, there is a composite plate tower (base layer: Q245R/layer: SS) with diameters of DN1200/DN2400 and a height of over 30 meters. The design pressure is 0.25 MPa, and the design temperature is 150°C. During the pre-commissioning phase, tears appeared around the fillet welds at the junctions between the DN600 manholes at elevations of 4.6 m and 17 m and the tank body; according to the photos provided from the site, the weld surfaces were uneven. The installation company believes that the excessive concentrated stress at the manhole locations during design, along with differences in linear expansion coefficients, was responsible for this issue. They wonder whether the different linear expansion coefficients of the two materials after welding could cause the welds to tear under heat exposure, thereby leading to corrosion of the tank body. They do not want to take any responsibility, so they require me to provide them with data to address this issue. How can I persuade them? Please give some advice. Thank you all!
It’s complete nonsense; when manufacturing composite panel equipment, it is necessary to carefully check whether the layers have been properly welded. The linear expansion coefficient isn’t as high as those who handle lifting operations claim, so tearing won’t occur due to this.
Is this so-called multi-layer weld tear merely a surface crack in the multi-layer structure, or is it a through-crack? If it is just a multi-layer crack, it is likely a welding issue with the multi-layer weld – the welding process or the welding materials were used incorrectly.
Without a detection report indicating the specific location of the defect, it is difficult to make further judgments; a thorough inspection of the torn part is necessary.
150 degrees, ? The bumps and tears you mentioned are on the SS side, right? If it is on the SS side, it is estimated that during welding, the transition layer was not thoroughly cleaned of CS, which led to contamination in the clad layer; over time, as the material was used, these internal defects grew larger. Conducting surface FE ion detection may reveal that the cladding weld metal contains Fe
This material is simply a regular stainless steel composite panel. I’ve also looked up relevant information, which states that it’s necessary to properly evaluate the welding process for such panels; otherwise, cracks are likely to occur! Now we’re facing a dispute: the installation company wants to shirk its responsibilities and insists that I provide data to prove that it’s not a problem related to concentrated stress or linear expansion coefficients I think the only option is to conduct finite element analysis, but it’s quite expensive and not necessary!
Use the blue dot method to perform a passivation film test to check for stress corrosion cracks.
It has little to do with the installation company; it’s probably a manufacturing issue
Well, the installation company and the manufacturer are the same.