NFPA 96 17A Class K Fire Protection Practice Test

Interior welding is allowed for seams, joints, and penetrations inside the hood, as long as the welds are smooth and cleanable. The emphasis is on keeping the interior surfaces continuous and easy to wipe down, which is essential in a grease-laden kitchen hood environment. When welds are inside, the exterior surfaces remain flush and free of protrusions, reducing places where grease can collect and making exterior cleaning easier, while the interior welds provide a sealed, durable seam. External welds would leave ridges on the outside that are hard to clean and could trap grease. Riveted joints create gaps and crevices that are difficult to sanitize, and soldered joints may not hold up to the heat and grease exposure. So, internal welding that results in a smooth, cleanable interior seam best supports the hood’s maintenance and fire-protection requirements.