City Affairs｜150 Degrees Celsius! "The Hot Spot Is Okay, The Quality Of The Work Under Our Hands Must Be Higher Than The Temperature."

City Affairs｜150 degrees Celsius! "The hot spot is okay, the quality of the work under our hands must be higher than the temperature."

Workers at Jiangnan Shipbuilding perform pre-weld preheating and post-weld insulation on hull riveting welds on steel plates exceeding 150 degrees Celsius. At this time, the hot summer we usually complain about does not seem so important. Behind this, there are not only extreme physical challenges, but also related to the quality cornerstone of China's high-end shipbuilding industry.

What does 156.6 degrees Celsius mean?

This number is not the ambient temperature, it is the preheating temperature before welding of thick marine steel plates. On July 3, 2025, at the Jiangnan Shipyard Manufacturing Department 2 on Changxing Island, Chongming, Shanghai, the air temperature in the outdoor area was close to 40 degrees Celsius. The steel plates to be processed were placed under the workers' feet, and their own temperatures were as high as 70 degrees Celsius.

In order to ensure that high-strength hull steel plates with a thickness of more than 35 mm can achieve defect-free welding, they must be heated to more than 150 degrees Celsius in advance. The reading of 156.6 degrees Celsius was actually measured by quality control personnel using a temperature measuring gun on site, which shows that the welding conditions meet the process requirements.

Why is such high temperature needed?

When welding thick steel plates, the huge heat input and subsequent rapid cooling generates strong shrinkage stresses. According to the quality manager of Jiangnan Shipbuilding Manufacturing Department 2, if preheating is not carried out, this stress can easily lead to serious defects such as cracks or lack of fusion in the welds, which will directly affect the structural safety of the ship. The structural safety of the ship here refers to the direct impact on its structural safety.

The internationally accepted shipbuilding regulations clearly stipulate this. For different grades and thicknesses of steel, the preheating temperature generally needs to be controlled within a specific range of 100 to 200 degrees Celsius. This step can significantly slow down the cooling rate after welding, thereby effectively releasing stress, thereby ensuring that the metal properties of the weld remain consistent with the base metal.

Workers’ confrontation and persistence

Even though the core welding work is performed by automated welding machines, workers still have to closely monitor the entire process. Welders should always pay attention to whether the newly formed weld is uniform and full. Once there is welding slag spatter remaining, it must be cleaned immediately with tools, otherwise slag inclusion defects will occur. Under the high temperature of the welding gun, the surrounding air has been distorted in the heat wave.

As a welder, Master Wang described that even though he was wearing a mask specially designed for welding, his face was still burnt red. The sweat evaporated as soon as it seeped out of the skin, leaving only white salt stains on the face. Occasionally, sweat drops from the eyelids will drip into the eyes, causing a stinging sensation. However, the work performed by the hands cannot be paused at all.

Sweat under full armor

To protect their skin from burns caused by the intense welding arc light and from being scalded by high-temperature welding slag splashing around, workers must wear a full set of protective equipment. This covers flame-retardant headgear, thick cloth work clothes that can prevent scalding, and leather hand protective gloves. City | 150 degrees Celsius! "The hot spot is okay, the quality of the work under our hands must be higher than the temperature." There are also professional labor protection shoes. However, under constant high-temperature radiation, the inside of these devices is like a steamer for steaming food.

Whenever there is a break, the workers take off their hoods and jackets, and the clothes underneath can squeeze out water. The work clothes made of anti-scalding cloth are often full of small holes formed by the welding slag melting through them all at once. This is the real appearance of their working environment. Every piece of damaged workwear records a close encounter with high temperatures.

Practical measures to deal with high temperatures

In the face of extreme weather in midsummer, the shipyard management made flexible work arrangements and implemented a "work at both ends and rest in the middle" system, which means taking full advantage of the relatively cool periods in the early morning and evening to carry out high-intensity operations, and arranging collective rest during the hottest period in the afternoon to ensure the health and safety of workers.

Multiple summer shelters equipped with air conditioners or large fans have been installed around each work area. The factory's logistics department supplies sufficient amounts of boiled and cooled boiled water, barley tea, and iced salt soda every day to help workers replenish water and electrolytes lost due to heavy sweating in a timely manner and prevent heatstroke.

Mass is higher than temperature

Under such difficult conditions, quality control has never been relaxed. The preheating temperature must be continuously monitored by a dedicated person and recorded. Every parameter such as current, voltage, and walking speed during the welding process is strictly monitored. Every time a weld is completed, it will be visually inspected immediately, and will undergo non-destructive testing after cooling.

The words of a master craftsman settled everyone's thoughts. He said: "It doesn't matter whether it is hot or tired. The quality of the pre-weld preheating and post-welding insulation of the riveted hull produced by us must be 'higher' than the temperature here." This simple promise ensures that every majestic ship that sets sail from here has steel-like strong bones that can withstand the wind and waves of the ocean. This pre-weld preheating and post-weld insulation that adheres to process standards for hull riveting in extreme environments is likely to be the key point for China's manufacturing industry to move towards the deep sea.

Faced with these workers who work in extreme environments to ensure the quality of "Made in China", in what ways do you think society and enterprises can provide them with more practical support and care? Feel free to share your views in the comment area.