Arguably the most heavily used section. It provides intervals for visual inspections, functional testing, and overhaul. The 2021 revision frequently introduces risk-based inspection (RBI) concepts, moving away from calendar-based schedules.
The official PDF is a copyrighted document that must be purchased. The price of MSS SP-81-2021 is . It is available for purchase directly from the MSS website, and through other major standards distributors like ANSI, Techstreet, Accuris, Intertek, and Nimonik. The standard is 14 pages long. It can be purchased as a PDF or a hardcopy. It is important to be aware of regional restrictions; for example, the PDF version of this standard is unavailable for purchase in Ukraine, Russia, and Belarus. Ms81-2021 Standard Pdf
Avoid “preview” PDFs claiming to be the full standard. Always verify the document ID: ISBN 978-1-7339281-3-9 (for the 2021 English edition). Arguably the most heavily used section
What you are running (machine cutting or sheet press work)? The nominal dimensions of your primary component parts. The official PDF is a copyrighted document that
As of 2026, several unofficial “free PDF” sites distribute corrupted, incomplete, or pre-release drafts of MS81-2021. Using these can lead to catastrophic equipment failures.
: Checking for leaks or ruptures under high pressure.