Backside Protection Methods for Stainless Steel Welding

With the rapid development of the petrochemical industry, stainless steel has become widely used in stainless steel welding, placing higher demands on pipe and plate welding. The previous stainless steel arc welding backing method has been gradually phased out in favor of argon arc welding. While argon arc welding backing is cleaner and faster than arc welding, it also presents some challenges. During welding, the backside of the stainless steel argon arc welding backing is susceptible to oxidation, resulting in defects. Therefore, backside protection is necessary to ensure the mechanical properties and corrosion resistance of the weld. Therefore, effective protection is essential when welding stainless steel.

Today, we will introduce several common backside protection methods for stainless steel welding:

01 Argon Backside Shielding Method for Stainless Steel Welding

Common shielding gases can be divided into pure argon and mixed gases. A certain ratio of argon and nitrogen mixed gas is more beneficial for welding austenitic stainless steel. Some inert gases are not used due to their high cost. Argon filling is a more traditional backside protection method for stainless steel welding, offering excellent backside protection, ease of use, high cleanliness, and a high pass rate. There are several methods for shielding with argon, including shielding with argon, localized shielding, and direct argon shielding at the weld joint.

1. Stainless Steel Welding Shielding with Argon

This method is commonly used in stainless steel welding of plates and large-diameter pipes. The shield is connected to a metal pipe and an argon hose. The argon valve is opened to fill the shield with argon. Another person holds the metal pipe as a handle, sliding the shield over the backside molten pool in sync with the welding on the plate or pipe. This effectively protects the backside. Its advantages include concentrated protection, reduced argon flow, and minimal argon waste.

2. Localized Argon Filling for Stainless Steel Welding

Localized argon filling is suitable for short, narrow pipes. Method: Seal the pipe weld with tape (to prevent air leaks). Seal both ends with sponge, rubber, or cardboard. Insert an argon hose from one end and fill with argon. Make a small hole in the seal at the other end (the sponge is unnecessary). This facilitates the base weld and prevents dents caused by excessive internal pressure. When welding stainless steel, to prevent excessive argon gas from escaping from the weld, tear off the weld sealing tape and weld it in sections. This minimizes argon gas loss and effectively protects the weld. Characteristics include waste, slow argon filling, and high cost.

3. Direct argon filling for stainless steel welds

For long, larger-diameter pipelines, localized argon filling is wasteful, can compromise quality, and can lead to high project costs. To save costs, direct argon filling at the weld can be used.