I. Quick Identification by Appearance FeaturesThe most intuitive way to identify cast iron elbows is through visual inspection:
- Surface Texture: Ordinary cast iron has a uniform grainy texture, while ductile cast iron features a smoother surface.
- Edge Treatment: Socket-type elbows have obvious tapers at the ports, whereas flanged elbows have evenly distributed bolt holes.
- Color Difference: Untreated cast iron is dark gray, and epoxy-coated products are mostly dark green.
II. Accurate Measurement MethodMeasure three core parameters using a tape measure and caliper:
- Center-to-End Distance: The straight-line distance between the centers of the two pipe ends.
- Bending Angle: Common angles include 45°, 90°, and 180°.
- Pipe Diameter Specification: When measuring the inner diameter, deduct approximately 3mm for the wall thickness.
III. Marking Symbol Decoding SkillsRegular products are usually cast with the following information:
- Material code (e.g., QT for ductile cast iron)
- Pressure rating (figures such as PN10 / PN16)
- Production batch code (combination of letters and numbers)
- Some manufacturers also mark symbols for applicable media.
