Mss Sp-55 Standard Pdf !new! Today

is the industry-standard quality specification for the visual evaluation of surface irregularities in iron and steel castings used for valves, flanges, and other piping components. Originally adopted in 1961, it provides a uniform method to identify and distinguish between acceptable and rejectable surface conditions. Core Purpose and Application

To fully implement SP-55, you should cross-reference these documents: mss sp-55 standard pdf

Inspectors compare the actual casting surface—typically within a 4-inch by 5-inch (100mm x 125mm) area—against these photographs to determine if it passes or fails. Types of Surface Irregularities The standard characterizes 12 distinct surface conditions: Cracks and fissures (linear fractures). Shrinkage (hollow spaces from solidification). Sand Inclusions. Gas Porosity (voids from trapped gas). Veins (ridges from sand movement). Rat Tails (depressions from mold buckling). Wrinkles, Laps, and Cold Shuts. Type VIII: Cut Marks (from mechanical cleaning). Scabs (slightly raised blemishes). Chaplets (incomplete fusion of mold supports). Weld Repair Areas. General Surface Roughness. MSS SP-55 vs. ASTM A802 Gas Porosity (voids from trapped gas)