Before the internet age, keeping up with the latest progress in a particular field of research was a problem that troubled many researchers. For niche topics in particular, aside from contacting other researchers, their only option was to comb through newly published journals.
In the eighties, this problem became even more difficult. The country had spent over a decade shut away, intensively practicing politics, so aside from Marxist theory, finding out what new discoveries had been made abroad was no longer something that could be accomplished by reading through the last few months of journals. Meanwhile, gaps in the ranks of researchers and missing records also made it difficult to establish whether related research had previously been conducted domestically.
So when Yang Rui said he had seen a journal describing ways to solve the problem of corner buckling in cans, Duan Hua was somewhat inclined to believe him.
Still, Yang Rui was only a high school student. Duan Hua merely straightened a little before asking calmly and seriously, "What are the four methods? Let's hear them."
Yang Rui's mother and father also looked curiously at their son.
"The first method is to increase the strength of the cans themselves. If I remember correctly, I think you can switch to better tinplate?" Yang Rui deliberately kept his explanation a little vague.
Duan Hua nodded, unsurprised. "You can replace 80p tinplate with 90p tinplate. Imported tinplate is another option. The Japanese have the best temper control, even better than the Americans. But a little factory like ours has no foreign exchange."
As he said the last sentence, Duan Hua raised his glass with a hint of self-mockery.
In 1982, foreign exchange was so precious that even senior central government officials had to budget carefully when traveling abroad. County-level institutions would ordinarily never even think of using it.
Yang Feng knew a little more about the matter. He raised his glass too, taking the initiative to clink it against Duan Hua's. "Doesn't your plant export dressed carcasses to Europe? I hear they sell quite well. Surely you get to retain some foreign exchange."
"Anything retained goes to the main plant. How could a branch plant like ours get an allocation? Switching to domestic 90p isn't very likely either. Spending more money doesn't count as ability. Besides, domestic tinplate is in very short supply too." Duan Hua spoke quite naturally. Founded in the sixties, the Xibao Meat Processing Plant had by now become an integrated meat-processing complex encompassing slaughtering, refrigerated storage and transportation, cooked meat products, and a whole range of other operations. The cannery, however, had only recently been established. Though its revenue was good, it was still a junior member.
Outsiders had no way to weigh in on these struggles for power and benefits within the big family of a state-owned enterprise.
Yang Rui did not think better materials would solve the problem either. Given the country's economic circumstances, even new product development prioritized low costs, let alone modifications to existing products.
Just as he had when dealing with corporate clients as a graduate student, Yang Rui smiled slightly and said, "Then I'll move on to the second point."
"Oh, go ahead." In response to the change in Yang Rui, Duan Hua unconsciously grew more serious himself.
"The second point is the temperature of the liquid in the cans. Controlling the temperature properly allows the pressure differential to dissipate slowly. I believe the reference gave a temperature somewhere in the eighties Celsius. You'd probably need to run some tests to find the exact setting." Yang Rui could not simply recite the value in the reference, so he narrowed the range as much as possible.
Still, different production lines and equipment naturally required different temperatures, and the factory would always have to make its own adjustments. That was also why equipment manufacturers provided after-sales service and factories had technical departments.
Duan Hua scratched his head. "Testing which temperature works best... that's a bit difficult. We're short of qualified people. The main plant mostly handles slaughtering and cutting, so they don't have anyone suitable either."
The Xibao Cannery was a newly established branch of the Xibao Meat Processing Plant, which meant it had few experienced hands to hold things together. Nor did it get a turn at recruiting the university graduates who had entered college after the entrance examinations resumed. Someone like Duan Hua already represented its highest level of expertise.
As a result, even a simple comparative test that an ordinary graduate student of a later era could conduct left the Xibao Cannery at a complete loss as to where to begin.
Yang Rui shook his head. "The third method relies on precooking and adjustments to can filling to resolve the corner-buckling problem as far as possible. This should be used in combination with the other methods. Thorough precooking, a reasonable fill weight, and so on."
"We do that already, but it really is difficult to determine the precooking time and the degree of filling." By now, Duan Hua was fully engaged and had genuinely begun discussing the technical issues.
"You can keep adjusting the precooking time and degree of filling, at least within a certain range. You should test them together with the temperature of the liquid."
"That's right... I'll think of a way to do that when I get back."
Yang Rui's parents looked from one to the other, feeling that something about the scene before them was not quite right.
Yang Rui was quite satisfied. He picked up a bite of food and smiled. "The fourth method offers the biggest improvement in the pass rate. Before that, let me ask: does the factory use a sterilization retort?"
"Yes, the GT7C3 model. We also call it a sterilization tank."
"A vertical one?"
"Yes. The freshly filled cans go in for high-temperature sterilization, then they're sprayed with water to cool them, and finally they're packed into boxes and shipped out." His uncle was no longer trying to test him; this was purely a technical discussion. He was already convinced that Yang Rui really had read relevant papers.
Pretending to recall what he had read, Yang Rui thought for a moment and said, "Does that model of sterilization tank spray cooling water upward from the bottom?"
"Hm? Yes, it does."
Yang Rui put on a look of sudden understanding. "Then that's it. To improve the pass rate significantly, you need to replace the vertical sterilization tank with a horizontal one."
"Why?"
"The book only gave the answer without going into much detail. I thought it over myself. See if this makes sense..." Assuming the manner of an eager-to-learn secondary school student, Yang Rui said, "If water is sprayed from below, it collects at the bottom. The cans at the bottom will definitely cool first, and those at the top will cool later, right? Also, as more water collects below, buoyancy gradually increases, and the cans at the top may float."
After all, Duan Hua had spent years working on-site. He nodded as he thought it through. "That's right. The ones at the bottom cool quickly, and the ones at the top cool slowly. The upper cans really could float. In that case, they wouldn't be fully immersed in the cooling water, so they'd cool even more slowly."
Yang Rui took the discussion further. "I remember the book saying that differences in temperature also create pressure differentials..."
"Mm..."
"Pressure differentials are the culprit behind corner buckling. In other words, this kind of vertical sterilization tank itself causes corner buckling, so it should be replaced." Yang Rui advanced his argument steadily, already certain of it.
Vertical sterilization tanks not only caused corner buckling, but were also one of its main causes. This was the conclusion reached by more than a dozen relevant papers in later years.
The cannery's current pass rate of just 75 percent was closely connected to this. Only by first modifying the sterilization and cooling process, then combining that with other minor measures, would it be possible to achieve a higher pass rate.
The simple but rigorous reasoning held Duan Hua's attention. He remained motionless, thinking it over carefully.
Yang Rui's mother knew nothing about the technical details. Seeing him like this, she thought Yang Rui had said something wrong and said with a smile, "Brother, don't think so much about it. Have something to eat first. The food's getting cold."
Duan Hua kept his head lowered and said nothing.
An inexplicable silence settled over the little courtyard. There was only the rustling of the pear tree as a light breeze brushed its branches, and faintly, a lingering fragrance seemed to drift over.
Smack.
Duan Hua slapped his thigh, making himself grimace in pain, but braced a hand on the table and stood up. "I have to head back. That's enough drinking for today."
"Hey, what's wrong?" Both of Yang Rui's parents stood up.
"Workshop Three has a horizontal sterilization tank. They can use either kind. I'll swap it over and give it a try. There's no time. I'm off, I'm off." Duan Hua picked up his briefcase and reached to pat Yang Rui's head, then paused and patted his shoulder instead. Laughing, he said, "Yang Rui really has grown up. You've been a huge help. I'll bring you something nice next time."
"Are you still inviting the expert, then?"
"Yes, to run the tests." As he spoke, Duan Hua dashed out of the courtyard at a jog and headed straight for the bus station.
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