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MSS SP-25 vs EN 19: valve body markings, nameplates and CE/PED differences

What belongs on the cast or forged body, what belongs on the nameplate, and how a European purchase order differs from a typical MSS SP-25 marking check.

Standards Comparisons2026-11-147 min read

MSS SP-25EN 19CEPEDnameplate

Short answer: MSS SP-25 is the marking system most US-style valve orders name. EN 19 is the European standard for marking metallic industrial valves. Both expect durable identification of the manufacturer, size, rating and material, and a flow mark on unidirectional valves. They are not interchangeable documents, and a European order usually adds CE (or UKCA) marking when the Pressure Equipment Directive or its UK equivalent applies.

By Kevin Lyu (吕中国), ValveWitness Inspection, Ningbo · Published 2026-11-14

In our sample report: Section 8 is a body-mark and nameplate check written to MSS SP-25. The body carries the maker’s mark, WCB, class 150, size 2 and heat H2611-07; the nameplate carries rating, trim and serial data. The heat mark was found, but the matching MTC was still pending (see EN 10204 and PMI). Download the sample report.

MSS SP-25 and EN 19 compared

The exact mandatory list is in the edition you name, together with the valve product standard. The table below is a practical comparison for buyers, not a substitute for those documents.

TopicMSS SP-25 (typical North American POs)EN 19 (typical European POs)
ScopeA marking system for new valves, fittings, flanges and unionsMarking and labelling of industrial metallic valves; read together with the valve product standard
Current edition at time of writingConfirm the edition named in the PO (widely specified editions include ANSI/MSS SP-25-2018)EN 19:2023 superseded EN 19:2016
Where marks goOn the body, or on an identification plate, or both. Quarter-turn valves may also use the handleIntegral marks on the body or bonnet and/or a firmly attached marking or identification plate, as required by the standard and the product standard
Identification of the makerManufacturer’s name or trademarkManufacturer’s name or trademark (and importer information where applicable)
Size and ratingSize and pressure class (for example NPS 2, Class 150)Nominal size (DN) and PN or Class, as specified
MaterialMaterial designation of the product (for example WCB on the body)Body material, plus other material marks required by the product standard
Flow directionRequired on unidirectional valves (arrow, or “inlet” / “outlet” / “high pressure side”)Flow direction for unidirectional valves
Heat or melt identificationCommonly required by the product standard and needed for MTC traceability; checked on the body in our sample reportAs required by the product standard or the order; still essential if 3.1/3.2 certificates are specified
CE / PED or UKCANot a requirement of MSS SP-25 itselfFor valves in the scope of the Pressure Equipment Directive, CE marking is a legal requirement. EN 19:2023 is the harmonised standard used to support nameplate conformity with PED marking requirements; UKCA follows the corresponding UK regulations
Painted-only marksMarks are to be integral (cast, forged, stamped, etched or similar) or on an attached plateDurable, legible marking; a paint-only mark is not a substitute for the integral or attached marks the standard requires

What belongs on the body, and what belongs on the nameplate

A nameplate can fall off, be painted over, or be swapped. That is why size, rating, material and the manufacturer’s mark are expected as integral marks on the body when the size and shape of the valve allow legible marking. The nameplate then carries the data that will not reasonably fit on the casting: rated pressure at a reference temperature, trim materials, serial number, the product standard, and any PO or tag number.

Marking item (sample report, Section 8)Typical locationWhy it is checked
Manufacturer name or trademarkBody (cast or forged)Identifies the maker independently of a later-fitted plate
Body material, pressure class, sizeBodyMust remain readable if the nameplate is lost or painted over
Heat / melt identificationBodyTies the casting or forging to the material certificate
Flow-direction arrowBodyOnly for unidirectional valves; not applicable to a typical gate valve
Nameplate: manufacturer, size, class, rated pressure at 38 °CNameplateCarries rating data that will not all fit on the body
Nameplate: body / bonnet / trim material, trim numberNameplateRecords trim (for example Trim 8) that is not always marked on the body
Nameplate: serial number, standard, PO or tag number if requiredNameplateTies the unit to test records and the order

CE / PED and what a European purchase order adds

MSS SP-25 does not itself impose CE marking. For valves placed on the EU market that fall within the Pressure Equipment Directive (2014/68/EU), CE marking is a legal requirement: visible, legible and indelible, on the equipment or on a securely attached nameplate. EN 19:2023 is a harmonised standard; conformity with it supports the nameplate information required by the Directive. The UK has a corresponding UKCA regime under its pressure-equipment regulations.

CE marking is not a substitute for the body marks, and it is not something a third-party PSI inspector “issues”. The manufacturer (or the importer) is responsible for conformity assessment and for affixing the mark. What the inspector can do is record whether the required marks and plates are present, legible and consistent with the order and the documents on site.

What to write into the purchase order

  • The marking standard (MSS SP-25 or EN 19) and the edition, plus the valve product standard.
  • Any project-specific marks: tag numbers, flow arrows, unique serials, country of origin.
  • For Europe: whether PED (CE) or the UK equivalent (UKCA) applies, and that the nameplate must carry the legally required data.
  • That heat identification on the body must be traceable to the material certificate.
  • That painted-over or missing body marks are a non-conformity, even if a new nameplate has been added at the end of the job.

Sources

  • ANSI/MSS SP-25, Standard Marking System for Valves, Fittings, Flanges, and Unions — MSS
  • EN 19:2023, Industrial valves — Marking of metallic valves — CEN; EN 19:2023 is the harmonised edition used to support PED nameplate requirements
  • Directive 2014/68/EU (Pressure Equipment Directive)
  • Our sample valve PSI report (fictitious data), Section 8.

We report facts from the samples inspected. Standards named in these guides are public standards we work to, not certifications or accreditations we hold. We do not issue product certificates or accreditation marks. Test pressures, durations, leakage rates and acceptance numbers must be read from the licensed edition named in your purchase order; we do not reproduce copyrighted tables from the standards.

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