Under what condition is seal welding of threaded joints permitted?

Seal welding of threaded joints is permissible when all threads are covered. This practice ensures that the weld effectively seals the connection, preventing leakage and promoting mechanical integrity. By covering all threads with weld material, it allows for a continuous seal without gaps that could lead to failure.

Furthermore, covering all threads minimizes the risk of stress concentration points that might develop if only partial welding occurs. This is especially important in high-pressure applications, where even small leaks can lead to catastrophic failures. Thus, ensuring that the entire threaded section is effectively sealed reinforces the purpose of welding, which is to provide a robust and durable joint.

Other conditions, such as pressure testing or specific temperature requirements, do not address the fundamental need for a complete and uninterrupted seal that is critical when seal welding threaded joints.