As a professional manufacturer and exporter of China brass brall valves, NAFCO has been making every and best efforts to control quality of brass ball valves, we're pleased to share the key important factors for brass ball valves. Factors that affects product quality of brass ball valves: 1. Raw Material: mechanical properties vary much from different material compositions, such as hardness, elongation, tensile strength, material is selected depends on brass ball valve working environment and applications. 2. Forging: proper temperature and forging pressure take important role, failing which may make cold knob or body defect for brass ball valves, some materials need tempering after forging to have better physical performance. 3. Machining sizes: the dimensions of body, bonnet, the heigth of stem hole 4. Brass ball: shape, deform, burrs, symmetry, the outer diameter tolerance: 1/2-1” max:0.04 11/4-2”max:0.06 21/2-4”max:0.08