FredG2:
The steel mills will often sell a 38” wide pl. with some small laminations in it, when they are well bounded, and within the mid-width and mid-thickness of the particular pl. Who defines ‘small’ and middle is another matter. They should not come to the surface or edge of the pl. This is fairly common (not unheard of), it just goes unnoticed, unless ASTM A53, or your spec. and P.O. specifically call out full UT inspection of the pls. and no laminations allowed. Then, the argument is, are they laminations or slag inclusions, which sometimes show up about the same on UT’ing. The argument goes that laminations usually do not cause many problems as long as they are parallel to the faces of the pl. and the primary stresses run parallel to both. They are a problem where primary stresses or residual stress in tension are perpendicular to the lamination and tend to pull it apart. And, they are a problem at unprotected edges, where you can see them and bitch about them, otherwise you go on your marry way, with few problems, and 40 years of service kinda proves this. It seems to me that, over the years, I’ve even fixed a few laminations at edges by gouging them out and welding them back up, although I’m not so sure many codes or AHJ would look kindly on that. They can be a problem in highly restrained joints and around welds and difficult detail geometry where you can have high primary and residual stresses in all three directions. I am not a defender of laminations or the mills selling you junk, but I’ve had these fights many times with different steel mills.
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