While the US has developed a special billion-dollar pen for the weightless conditions of spaceflight that writes in all conditions, the Russians use an ordinary pencil. 🙂 This joke reminded us of our new, but workable solution to vetting batches of cans from our suppliers. Since we have recently dealt with the annoyance of a batch of cans with a faulty sheet metal weld in the joint, we decided to always subject the first can of a new batch from a supplier to a stress test in addition to the normal package closure measurement and normal pressure test. Briefly, a valve is fitted and sealed into the closed can, this is connected to pressurised air and the can is pressurised under water until the cap is removed, whilst maintaining safety precautions. In doing so, it is checked to ensure that no bubbles escape at any joint before the lid is removed. This guarantees the quality of the batch. The humorous thing is that million dollar X-ray systems do not detect this as they are focused on checking the cap or foreign bodies. However, the strength of a welded (but perhaps inadequately) joint may not be visible.
