Once you open the , you will find:

: This standard is frequently cited in ASTM specifications (like ASTM A216 or A352). If a purchase order specifies "Inspection per MSS SP-55," the manufacturer must verify that the casting surfaces match the "Acceptable" photos in the guide.

It is referenced extensively in valve and piping specifications (such as API 600 and ASME B16.34) to define what a "commercially smooth" casting looks like.

The MSS SP-55 standard serves as a visual guide for identifying surface irregularities in steel castings for valves, flanges, and fittings, featuring 60 reference photographs to differentiate between acceptable and unacceptable defects. Updated in 2025, this standard acts as a critical quality control tool that complements broader ASTM specifications. Access the official standard from the Manufacturers Standardization Society (MSS) . MSS SP-55-2001 - Peninsula Alloy Inc.

If you are looking for a PDF version of this standard, keep the following in mind: