04/08/2026
𝐖𝐡𝐚𝐭 𝐢𝐬 𝐬𝐞𝐚𝐥 𝐰𝐞𝐥𝐝𝐢𝐧𝐠
A 𝐬𝐞𝐚𝐥 𝐰𝐞𝐥𝐝 is a weld applied exclusively to achieve fluid tightness (leak prevention) rather than to provide structural strength or load-bearing capacity.
𝐊𝐞𝐲 𝐏𝐫𝐢𝐧𝐜𝐢𝐩𝐥𝐞𝐬:
• 𝐍𝐨 𝐒𝐭𝐫𝐞𝐧𝐠𝐭𝐡 𝐂𝐨𝐧𝐭𝐫𝐢𝐛𝐮𝐭𝐢𝐨𝐧: Pressure vessel calculations cannot factor in the strength of a seal weld. The mechanical joint (such as threads, expander joints, or primary structural welds) must support all design loads.
• 𝐌𝐚𝐭𝐞𝐫𝐢𝐚𝐥 & 𝐏𝐫𝐨𝐜𝐞𝐝𝐮𝐫𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥𝐬: Seal welds must use compatible filler metals and be performed by qualified welders following approved Welding Procedure Specifications (WPS) to prevent cracking.
• 𝐂𝐨𝐦𝐦𝐨𝐧 𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬: Frequently utilized on threaded connections, tube-to-tubesheet attachments, and backing rings where process fluids must be securely contained.
• 𝐈𝐧𝐬𝐩𝐞𝐜𝐭𝐢𝐨𝐧: While exempt from radiography meant for primary structural welds, they remain subject to visual examination and the vessel's final hydrostatic test.
