Copper pipes are the "refrigerant-transporting blood vessels" of cold storage refrigeration systems, and welding quality directly determines the system's sealing performance and service life. Common problems in welding, such as out-of-control temperature and wrong material selection—like using an overheated flame that burns through copper pipes, or replacing 35% silver-containing silver welding rods with ordinary brass ones—will leave fatal hidden dangers such as refrigerant leakage and cracking in cold storage, with subsequent maintenance costs far exceeding the initial savings.

          Flame temperature control is the core of welding. Neutral flame is required for copper pipe welding, with the flame core kept 1-2 cm away from the pipe wall, and the temperature accurately controlled at around 1083℃. An overly strong flame or too short a distance will instantly burn through the copper pipe and form holes; insufficient temperature will cause uneven melting of the welding material, failing to form a tight weld joint. High temperature will also cause oxide scale to form on the inner wall of the copper pipe, which is prone to clogging the throttle valve after falling off, leading to a sharp drop in refrigeration efficiency.

          There must be no compromise in welding rod selection. Silver welding rods containing 35% silver have a low melting point, good fluidity, and strong weld joint toughness, which can withstand the long-term temperature and humidity changes of cold storage. Ordinary brass welding rods have a high melting point and high brittleness, making weld joints prone to microcracks. Especially in the low-temperature environment in winter, thermal expansion and contraction will expand the cracks, causing Freon leakage. Refrigerant leakage not only increases the cost of refrigerant refilling but also causes the unit to operate under overload due to insufficient refrigerant.

          Dual inspections are required after welding to ensure quality: apply soapy water to the weld joint and check for no air bubbles; then conduct a nitrogen pressure holding test, where the pressure drop should not exceed 0.05MPa within 24 hours under 1.8MPa. At the same time, residual welding slag at the weld joint should be cleaned to avoid corrosion of the outer wall of the copper pipe.

           Cold storage copper pipe welding must strictly adhere to the principle of "temperature control + correct material selection". Only by welding with neutral flame and matching 35% silver-containing silver welding rods can the weld joint be ensured to be tightly sealed and highly crack-resistant. Ignoring these details may seem to save a small amount of money, but in fact, it will lead to major problems such as refrigerant leakage and shutdown. Only standardized operations can lay a solid foundation for the refrigeration system.