In tool-steel there should be no seams at all. Some makers declare that in high steel, seams are evidences of good quality; such a statement is the veriest fraud; it is hard to get any high steel free from seams, and therefore if the maker can get the user to believe that a seam is a good thing he can enhance his profit; that is, he can enhance it for a time until his fraud is understood.
Some seams are hard to see; when there is reason to suspect one, a little filing across the line will show it in a distinct black line if it is there. A file is an indispensable tool for an inspector, better than a chisel or a grindstone.
In machinery and structural steel a few small seams may be unobjectionable; too close inspection may lead to unnecessary cost without a compensating gain; still every engineer should reserve the right to determine what seams are allowable and what are not, for his own safety.
Laps should not be tolerated in any work.
Torn cracks on edges or surface indicate burned steel or red-short steel; they should not be allowed.
The grain of steel should be practically uniform, not too coarse, not with brilliant lustre, nor with a dark india-ink tint. With an even fine grain, a bright lustre may indicate a mild steel not worked badly. Inspectors must learn by practice what is tolerable and what is not, as it is impossible to lay down hard and fast rules; it is safe, however, to say that a fairly fine grain of even texture, not much lustre, and no india-ink shade, is indicative of good heating and proper working.
With these few general hints the subject must be left, for, like tempering, inspecting is an art in itself, and it cannot be taught in a book.
An expert inspector will see seams and pipes with his naked eye that a novice could not detect with an ordinary magnifying-glass.
It may do no harm to the inspector to suggest to him that amiability and good sense are the best ingredients to mix with sound judgment.
If he will cultivate these, and learn to distinguish between a mere blemish and a real defect, he will find his work made easy and pleasant; and he will be far less likely to have bad work thrust at him than he will if he makes it apparent that he regards himself as the only honest man.