[Visual Inspection of Casting Surface] │ ▼ [Identify Irregularity Type (A through I)] │ ▼ [Compare with MSS SP-55 Reference Photos] │ ┌──────────┴──────────┐ ▼ ▼ [Within Limits] [Exceeds Limits] │ │ ▼ ▼ [ACCEPT] [REJECT / REPAIR] │ ▼ [Weld Repair per] [ASME IX / ASTM ] Step 1: Cleaning and Preparation

Need a single section for a toolbox talk? Print only pages 4–7. Need a full-color reference for the shop floor? Print the relevant comparison plates.

: Two photos for each irregularity type illustrate what is considered a commercially acceptable surface finish.

❌ – The text alone is useless; you need the plates. ❌ Applying to non-steel castings – SP-55 is for steel only (not iron or brass). ❌ Ignoring size limits – A small shrinkage in a low-stress area may be acceptable; the same defect on a sealing surface fails. ❌ Outdated revision – Pre-2011 versions lack clarity on digital image matching.

is the industry-standard guide for visually evaluating surface irregularities in steel castings used for valves, flanges, and piping components

Primarily external. Internal surfaces are usually covered by the purchaser's specification, but the standard can be invoked by contract.

In commercial projects, relying on pirated, low-resolution, or outdated scanned PDFs of MSS SP-55 can lead to severe operational risks:

MSS standards are and not freely available from unauthorized sites. To obtain a legitimate PDF:

The most recent update, , expanded the scope of the standard to include iron and ductile iron castings in addition to steel. The 12 Types of Surface Irregularities

Chaplets must be fully fused. Unfused chaplets or those showing signs of leakage paths are rejected. 6. Porosity / Gas Holes (Type F & G)

The defining feature of the MSS SP-55 work instruction is its set of reference photographs. For the categories listed above, the standard provides side-by-side photographic examples: