How many locations must soot blower screw connections be tack welded to prevent coming loose?

Tack welding soot blower screw connections at three locations is the correct practice to ensure they do not come loose. This method provides adequate security for the connections, as three points of contact create a stable structure that helps maintain the integrity of the joint during operation.

The reasoning behind requiring three locations relates to the mechanical forces experienced in an operational environment. Soot blowers are subject to vibrations and thermal expansion, which can contribute to loosening over time. By using three tack welds, you distribute the load and stress over a wider area, thereby reducing the likelihood of failure at any one point.

While fewer tack welds might seem sufficient, they do not provide the same level of stability and security as three. A single tack weld may not resist the forces effectively, and two may not fully stabilize the connection in all scenarios, especially under varying operational conditions. Thus, three locations create a more robust and reliable connection for soot blower screw fittings.