Stainless Steel Buttweld Caps

Dingjin was established in 2000 and specializes in dished heads, which are larger than caps. Dingjin expanded its cap business to meet clients' one-stop purchasing requirements. The following information was summarized from executed orders.

Stainless steel butt-welded caps supplied by Dalian Dingjin are a type of pipe fitting widely used in construction and industrial applications. Made of stainless steel, they are connected to pipeline systems by welding. Their excellent corrosion resistance, wear resistance, high strength, and high-temperature performance contribute significantly to the overall reliability of the pipeline system. Pipe caps are used together with other pipe fittings to facilitate both pipeline connection and fluid transport while improving system stability and operational safety. They can adapt to complex operating conditions and help reduce maintenance costs.

Dingjin's stainless steel butt-welded caps are joined by welding, offering advantages such as a compact structure, high joint strength, and excellent sealing performance. Compared with other joining methods, butt welding provides greater reliability and durability.

During welding, the arc length should be kept short, the electrode angle should be adjusted properly, and the assembly gap should be reduced as appropriate. Dingjin usually adopts the practice of holding the electrode slightly longer at the end of the weld; however, excessive dwell time should be avoided, as it may cause the temperature of the molten pool to become too high, resulting in excessive weld reinforcement or other defects. It is recommended to use intermittent arc extinguishing: extinguish the arc after a brief pause, then reignite it after the weld pool has cooled slightly, and fill the crater with a certain amount of molten metal. This allows the welder to fill the crater several times. However, the intermittent arc extinguishing method is not suitable for alkaline DC electrodes, as it may easily cause porosity.

Undercut is another common welding defect encountered by Dingjin. It may occur continuously or intermittently. Undercut reduces the effective cross-sectional area of the base metal, weakens the strength of the welded joint, and creates stress concentration at the undercut edge, which can serve as an initiation point for cracks that may develop under service loads.

The following factors should be minimized to prevent undercut: using an excessively high welding current or an excessively slow welding speed during flat welding; using an excessively long arc, which increases the melting width and produces a strong arc blow force, causing grooves to form in the base metal that cannot be adequately filled with weld metal; and applying incorrect electrode angles or improper weaving motions during fillet welding, or maintaining an excessive arc length, which may cause undercut along the upper edge of the weld.

When the welding current is high, insufficient dwell time on both sides of the groove during electrode movement, combined with an excessively long arc length, can cause the temperature of the molten metal in the center of the weld to become too high, resulting in weld pool collapse or sagging. Consequently, the base metal on both sides may be blown away by the arc, leaving the molten pool insufficiently filled. The molten metal produced during welding may also contribute to the formation of undercut.