The steel pipe stood upright in the crack in the ground without falling over. Chen Hao looked at it for two seconds, then turned around to get the testing equipment.
He placed the instrument on the window frame and pressed the start button. The red light flashed three times, turned yellow, and then emitted a short beep. Susan stood beside him recording the data, her pen pausing: "Leakage value exceeds the limit."
"Let's do it again," Chen Hao said.
The second test yielded the same result. The third window, the fourth, and five windows in a row all triggered alarms. When the air was pressurized to the standard value, the sensor readings at the seams fluctuated erratically, and some even lit up red.
“It’s not an isolated problem.” Carl squatted down to listen to the wind. “I can hear whistling sounds, like someone is whistling.”
Susan walked to the bottom of the door, took out a thin piece of paper, and slipped it under. With a gentle pull, the paper brushed against the gap. "There's enough space to fit two coins," she said, looking up. "If the water comes, it won't be able to stop it."
No one spoke. The newly installed doors and windows were neatly arranged along the wall, appearing to fit perfectly, but in reality, they leaked air everywhere.
Chen Hao bent down, opened his toolbox, and took out a flashlight, shining it on a seam. The beam swept across the edge of the adhesive strip, revealing tiny cracks, like chapped lips in winter.
“We thought tightening the screws would be enough,” he said, “but the wind still blew it right through.”
Nana had already connected to the monitoring system, and the screen was displaying a scrolling data stream. A few seconds later, she brought up the material usage log and the temperature difference change graph.
"Our initial assessment is that the sealing strip material and the metal frame have mismatched coefficients of thermal expansion and contraction," she said. "When the temperature drops by more than 15 degrees Celsius at night, the rubber shrinkage rate is higher than that of the aluminum, causing the joint to detach."
"So, it looks fine during the day, but starts leaking at night?" Carl asked.
"Yes," Nana nodded.
Susan flipped through the installation record sheet in her hand: "This batch of rubber strips was replaced last week. They said it's wear-resistant and tear-resistant, and its performance is 30% better than the old model."
"The parameters look good, but they don't work in real combat." Chen Hao put the testing instrument back in the box. "We've been fooled by the data on paper again."
"It's not exactly a lie," Carl said, scratching his head. "Who knew it was afraid of the cold?"
“There are relevant records in the extreme environment building case library.” Nana pulled up the data page. “The Mars outpost once experienced cabin depressurization due to a similar problem. It was subsequently replaced with flexible silicone-based composite material, which solved the sealing failure under the temperature difference between day and night.”
"Then let's change it." Chen Hao stood up. "Let's change it now."
“We don’t have this glue in stock,” Susan reminded them.
“We have the raw materials.” Nana quickly searched and said, “The base has A-type silicone gel and b-type crosslinking agent in stock, which can be mixed in proportion and processed on-site into the required sealing material.”
"How do we match them?" Karl leaned closer to look at the screen.
"The ratio of materials is 3:1, the mixing time is no less than seven minutes, and it needs to be left to cure for two hours after application," Nana demonstrated the flowchart.
“Sounds easy.” Carl rubbed his hands together. “I’ll adjust it.”
"Don't rush," Susan stopped him. "Even half a gram difference can affect the performance. Last time when we were making the fire-retardant coating, you added an extra spoonful, and it started to produce black smoke when it burned."
Karl withdrew his hand: "Then who do you think will come?"
“I’ll weigh it,” Susan said. “You’re in charge of stirring, but you have to do it exactly the time Nana gives you, not a second less.”
“Okay.” Carl nodded. “Then you’d better keep a close eye on the scales.”
Chen Hao made the decision: "Starting today, all new door and window installations will be suspended. Remove any substandard ones and redo the sealing. This time, we won't rely on feel; we'll only look at the data."
"How much do we need to demolish?" Susan asked.
"Check the first ten doors first," Chen Hao said. "Which one fails the test, rework it."
They split up. Nana set up a temporary monitoring terminal to track data feedback from each process in real time; Susan counted the raw material barrels and prepared the weighing equipment; Carl found an old mixer, plugged it in, and tested it; Chen Hao, carrying a wrench, headed towards the first window that needed to be dismantled.
One by one, the screws were loosened, and the window frame slowly detached from the wall. Chen Hao lifted it with force, and the entire window was removed and leaned against the wall. He looked back at the original installation location and found that the old adhesive strip had hardened, and the edges were curled up, like a withered leaf stuck to cement.
"No wonder it wouldn't stick," he said.
Carl took a scraper and went to clean up the remaining adhesive. The blade scraped across the metal surface, making a hissing sound. After cleaning each section, he rinsed it with water, let it dry, and then applied a primer.
Susan had already started preparing the new materials. She placed the electronic scale on a stable surface, first pouring in type A silicone gel, then slowly adding agent B. The numbers on the screen fluctuated, and she stared at the last decimal place until it was completely stable before stopping.
"Three to one," she said. "Start the timer."
The mixer started, and the slurry spun slowly in the container. Seven minutes later, the machine stopped automatically. Susan scooped out a small amount and performed a string test, confirming that there were no particles or separation.
“It’s ready to use,” she said.
Chen Hao put on gloves and took the glue gun. Nana projected a standard application path beside him—four millimeters wide, three millimeters thick, with an extra ring of reinforcement at the corners.
He slowly pushed the adhesive along the edge of the window frame, squeezing it out evenly, like squeezing toothpaste. After applying a section, he immediately smoothed it out with a scraper, making sure there were no air bubbles or breaks.
“This work is meticulous,” Carl said, standing to the side watching. “It’s even more meticulous than when I weld frames.”
"I used to think installing a window was a big deal," Chen Hao said, wiping the sweat from his brow. "Now I realize that even delicate work can go wrong."
The first window was sealed and reinstalled. Nana connected the testing equipment and began a new round of pressure testing.
The crowd gathered around, staring at the reading screen.
The pressure gradually increased, but the sensor readings stabilized. Ten seconds, twenty seconds, thirty seconds passed, and the alarm did not sound.
"Passed," Nana announced.
Susan noted down the number and put a checkmark on the form.
“Again.” Chen Hao took off his coat, revealing sleeves stained with glue. “There are still nine more to come.”
As night deepened, the workshop lights remained on. New sealing materials were being mixed in batches, old windows were being removed one after another, and new processes were being implemented step by step.
By 2 a.m., the tenth window had also passed the inspection. Seven out of the ten windows passed the test on the first try, and the remaining three passed the retest after minor adjustments.
"100% pass rate." Susan closed her notebook. "Much better than before."
Chen Hao sat on the floor, leaning against the tool cabinet. He reached out and touched a window he had just finished, his fingers tracing the seams, which were smooth and even.
“This time it’s really blocked,” he said.
Nana updated the process manual, saving the new recipe and operating procedures to the shared directory. Susan sorted and labeled the remaining ingredients. Carl disassembled the mixer to clean out any residue and prevent future blockages.
"We have to continue tomorrow." Chen Hao stood up. "We can't miss any of those windows in the back."
"How about we hire two more people to help?" Carl suggested.
“More people doesn’t necessarily mean faster,” Susan said. “In this kind of work, one wrong step and you have to start all over again.”
"Then let's take it slow, the four of us," Chen Hao said, stretching his shoulders. "Anyway, we're not expecting to build a fortress overnight."
He walked to the workbench, picked up an unopened glue gun, and checked whether the nozzle was intact.
"Who's next?" he asked.
Susan flipped through the list: "Window number eleven, the one at the end of the east corridor."
Chen Hao nodded, tore open the packaging, and inserted the new tubing into the gun.
He pulled the trigger to test the pressure, and the colloid slowly oozed out from the tip.
Carl walked over carrying his toolbox and handed him a scraper.
Chen Hao took it and walked towards the corridor.
The light shone behind him, casting a long shadow.
He walked to window number eleven and placed the glue gun against the starting point of the window frame.
The finger pulled the trigger.
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