What is the best practice for cooling welds after completion?

Allowing welds to cool naturally is considered the best practice for a variety of reasons. Firstly, natural cooling helps to minimize the risk of introducing stresses into the weld area that can lead to warping or cracking. Rapid cooling methods, such as using water, can cause the metal to harden too quickly, resulting in a brittle weld, which may compromise the integrity of the joint.

Additionally, forced cooling, such as using a fan, can create uneven temperature distributions in the weld and surrounding material. This uneven cooling can lead to residual stresses, making the weld more susceptible to failure under load.

Quenching in oil is also not advisable as it can introduce thermal shock to the weld, again leading to cracking or detrimental changes to the microstructure of the weld metal. Therefore, allowing the weld to cool naturally is the most effective way to ensure the weld maintains its desired properties and strength.