XII.INSPECTION.
Careful and systematic inspection is of the utmost importance from the first operation of melting to the last act of the finisher.
Assuming that every operator is honest and conscientious in the performance of his work, the personal equation must be considered, as well as the exigencies of the many operations. The steel-maker must inspect his ingots to see that they are melted well and teemed properly, that they are sound and clean, and to determine their proper temper.
When work is finished, he must inspect it to see that it has been worked at proper, even heats, that it is correct in dimensions, and that all pipes and seams have been cut out. After all this has been done faithfully it were well that his work were done when it were well done. Such is not his happy lot; every successive manipulator may ruin the steel by carelessness or ignorance, and it is a gala day for a steel-maker when he does not receive some sample of stupid ignorance or gross carelessness, with an intimation that it would be well for him to learn how to make steel before he presumed to offend by sending out such worthless material. And sometimes, though not so often if he knows his business, he finds a complaint well founded; then he must regulate his own household and make his peace with his angry customer as best he can.
The engineer must inspect his steel to see that it is sound, and clean, and finished properly, as he has a right to expect that it should be.
It is not intended here to lay down rules for shop and field inspection,—that is an art in itself outside of the function or the experience of a steel-maker,—but some hints may be given as to the examination of steel as it comes from the mill, and it has been the aim in previous chapters to give such information as may enable an engineer to form a good judgment as to matters which are not likely to come to his knowledge in the course of ordinary practice.
Steel should be sound; it should be examined before it is oiled or painted. All pipe should be cut off; a pipe of any considerable size will show in the end of a sheared bar, and a careful observer will soon learn to detect it. If there is reason to suspect a pipe, file the place and the pipe will be revealed if it is there. Do not chip at it, for a chisel will often smooth a line which a file will bring out. In tool-steel there should not only be no pipe, there should be no star left in the bar. A “star” is a bright spot which shows the last of the pipe, not quite cut away; the steel is not solid in the star and it will not make a good cutting-edge; it may even cause a sledge to split.
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.
Lapsshould not be tolerated in any work.
Torn crackson 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.