Industrial valve failures rarely start with something dramatic. Very often, they start with something small: a wrong grade on the nameplate, an MTR nobody really checked, or a body casting that does not match the paperwork.
In this NTIA guide, we bring valve nameplates, Material Test Reports (MTRs) and material identification together into one practical workflow you can use during vendor inspection and receiving inspection.
At a glance
- Valve nameplates and body markings show what the valve claims to be: size, pressure class, material and standards, marked in line with ISO 5209 and product standards such as ASME B16.34 and MSS SP-25.
- MTRs/MTCs show what the material actually tested as, typically using EN 10204 Type 3.1 or 3.2 certificates.
- Material identification (markings, traceability and PMI) closes the loop between the valve body in front of you and the data on the certificate, following best practice from API RP 578 and related standards.
Your job as an inspector is to answer three simple questions:
Does the nameplate match the PO and datasheet?
Does the MTR match the specified grade and standard?
Does the physical valve (markings, PMI) clearly match both?
The rest of this article gives you the tools to answer “yes” with confidence – and to know exactly what to do when the answer is “no”.
1. Valve Nameplates & Body Markings: Reading the “Front Door”
1.1 What good valve nameplates must tell you
General marking rules for industrial valves are defined in ISO 5209:2019 – General purpose industrial valves – Marking. It specifies which markings are mandatory, which are optional and where they can be applied (on the body, on a flange or on an identification plate).
Product standards such as ASME B16.34 then add more detail and typically require marking on the valve body plus an identification plate, in line with MSS SP-25 – Standard Marking System for Valves, Fittings, Flanges and Unions.
On a real project valve, you should be able to read at least:
- Manufacturer’s name or logo
- Valve type/model and serial or heat number
- Nominal size (DN or NPS)
- Pressure rating (PN or Class)
- Body and Trim material designation (e.g. ASTM A216 WCB, CF8M, 1.4462)
- Design and test standards (e.g. ASME B16.34, API 6D, API 598 or ISO 5208)
- Flow direction where required
Project specifications often add:
- Tag number and line number
- Special service (e.g. oxygen cleaned, sour service, fire-safe)
- Test pressure and test medium
If the nameplate is incomplete, inconsistent or looks easy to change, you already have a potential material or marking risk.
1.2 Typical nameplate layout (and where information hides)
Manufacturers use different graphic layouts, but most valve nameplates follow a similar structure:
- Top line: manufacturer and model/type
- Middle lines: size, class/PN, body material, trim or seat material
- Bottom lines: tag number, serial number, design and test standards
Some information may sit on the body or bonnet casting instead of the nameplate:
- Pressure class (for example, 150 / 300 / 600 / 900…)
- Body material code
- Heat number or foundry mark
When you do a vendor inspection, walk around the valve and deliberately look for:
- Nameplate
- Machined pad markings
- Casting marks on body and bonnet
- Any secondary plates (e.g. NACE, fugitive emission, ATEX)
The methodical walk-around is described in Visual & Dimensional Checks: Step-by-Step and built into Valve Inspection Checklist (PDF): Visual, Dimensional, Testing.
1.3 Red flags in valve nameplates and markings
Treat any of these as “stop and think” moments:
- Material code on the plate does not correspond to any recognised standard
- Pressure rating on the nameplate does not match the body marking or datasheet
- Tag number missing, duplicated or clearly wrong for the service
- Nameplate attached in a way that makes it easy to remove or swap
- Ground-off or re-stamped markings with no documented reason
In those cases:
- Do not rely on the nameplate alone.
- Move immediately to MTR review and material identification.
- Note your observations for the inspection report and, if needed, prepare to raise an NCR in line with Vendor Inspection Reporting: IR/NCR/Final Dossier and Common Vendor Nonconformities & Fixes.
2. Material Test Reports (MTRs) for Valves: What the Paperwork Really Says
2.1 What an MTR/MTC actually is
A Material Test Report (MTR) – or Mill Test Certificate (MTC) – is the document issued by the material manufacturer confirming that a specific batch (heat) of material meets the chemical and mechanical requirements of the ordered standard.
Under EN 10204, the most common inspection certificate types for valve materials are:
- Type 3.1 – manufacturer declares compliance and provides test results; signed by a representative independent from production (usually QC).
- Type 3.2 – like 3.1, but with additional validation from an independent inspection body or the purchaser’s inspector.
For critical valve components (bodies, bonnets, pressure-containing parts), projects typically require Type 3.1 or 3.2, not 2.1 or 2.2.
The principles and differences are explained in more depth in EN 10204 3.1 vs 3.2: Differences Explained and the practical reading process is captured in MTC Interpretation Guide + Checklist (PDF).
2.2 Fields inspectors must always check
When you pick up an MTR for a valve body or bonnet, you should be able to answer six questions quickly:
- What standard and grade is this material?
- Example: EN 10213 1.0619; ASTM A216 WCB; ASTM A351 CF8M.
- Which heat is this?
- Heat number and product description must match the stamps on the valve.
- Are the chemical limits correct?
- All elements specified in the standard and project spec must be within limits.
- Are the mechanical properties acceptable?
- Yield strength, tensile strength, elongation and, where required, reduction of area.
- Is impact performance proven where needed?
- Charpy test temperature and energy values must meet or exceed requirements for low-temperature or sour service.
- Is the certificate type and signature acceptable?
- Type 3.1/3.2, correct signatory, date and clear link to the material supplied.
Working through MTC Interpretation Guide + Checklist (PDF) with a printed MTR in your hand is still one of the fastest ways to improve consistency across inspectors.
2.3 Typical nonconformities in valve MTRs
Some of the most common issues you will see in valve projects are:
- MTR issued as EN 10204 Type 2.2 when the spec clearly calls for 3.1 or 3.2.
- Grade or standard on the MTR does not match the valve datasheet (for example, EN vs ASTM mismatch without explanation).
- Heat number on the valve body does not appear anywhere on the MTR set.
- Impact tests are missing, or performed at the wrong temperature for the specified service.
- MTR looks generic and unrelated to the actual hardware on the shop floor.
Each of these is a material documentation nonconformity and should be treated as such in your reports, using the structure from Vendor Inspection Reporting: IR/NCR/Final Dossier.
3. Material Identification in Practice: From Marks to PMI
3.1 Casting marks, stampings and colour codes
Material identification is not just about high-tech PMI guns. It starts with simple things:
- Casting marks on bodies and bonnets (foundry code, heat number, material code).
- Stamped markings on flanges, pads or yokes (class, material, standards).
- Paint colour codes or tags used by the manufacturer to differentiate materials.
- Temporary tags used to track components through machining and assembly.
Your first task is to make sure:
- Every pressure-containing part has clear, permanent markings.
- Every marked heat number can be traced back to a specific MTR.
- Temporary colour codes and tags are consistent with the documentation.
The practical steps for checking castings, dimensions and general condition are described in Visual & Dimensional Checks: Step-by-Step and built into Valve Inspection Checklist (PDF): Visual, Dimensional, Testing.
3.2 Positive Material Identification (PMI) for critical valves
For alloy steels, stainless steels, duplex and critical services, projects increasingly require Positive Material Identification (PMI) as part of a Material Verification Program (MVP).
API RP 578 provides guidance on how to set up such MVPs for new and existing assets, and many valve service companies now perform PMI in accordance with API RP 578 and MSS SP-137.
In practice, PMI is used when:
- The risk of material mix-up is significant (many heats, many suppliers).
- The consequences of error are high (high temperature, sour service, hydrogen, toxic media).
- There are gaps or inconsistencies in documentation.
PMI Testing: What, When & How to Document explains how to:
- Select which valves and components to test.
- Choose the right PMI method (XRF vs OES).
- Record PMI locations, results and acceptance criteria in your inspection report and final dossier.
3.3 Joining the dots: nameplate → MTR → PMI
For a single valve, the complete material story looks like this:
- Nameplate and body markings declare the material (e.g. ASTM A216 WCB or CF8M) and standards.
- Casting/forging marks and heat numbers connect that body to one or more specific MTRs.
- MTRs show that each heat meets the chemical and mechanical requirements of the ordered standard.
- PMI results (where required) confirm that the actual alloy in the body and bonnet matches the declared grade and MTR.
If any link in this chain is missing or inconsistent, you have a material identification issue and should treat the valve as nonconforming until resolved, using the approach described in Common Vendor Nonconformities & Fixes.
4. Step-by-Step Workflow for Verifying Valve Materials
This is a practical workflow you can drop into an ITP or checklist for valve shop visits and receiving inspections.
Step 1 – Start from the documents (not the valve)
- Review the PO, valve datasheet and drawing.
- Highlight required valve type, size, pressure class, body and trim materials, design and test standards.
- Note any special requirements: NACE, fugitive emissions, low temperature, oxygen service, etc.
Step 2 – Check the nameplate and markings
- Read the complete nameplate: manufacturer, model, size, class/PN, materials, standards, tag number.
- Cross-check tag number against valve list.
- Inspect body and bonnet castings for material codes and heat numbers.
- Note any missing, inconsistent or suspicious markings.
Step 3 – Link hardware to MTRs
- For each unique heat number on bodies/bonnets, retrieve the corresponding MTR.
- Using MTC Interpretation Guide + Checklist (PDF), confirm:
- Standard and grade,
- Chemical and mechanical properties,
- Impact tests where required,
- Certificate type (3.1/3.2) and traceability.
Step 4 – Resolve EN vs ASTM material questions
- If your datasheet uses ASTM grades and the MTR shows EN grades, or vice versa, consult EN vs ASTM: Common Material Specs Mapped.
- Decide whether the delivered grade is a true functional equivalent for this application.
- Where necessary, coordinate with design to obtain formal approval for substitution.
Step 5 – Perform material identification (including PMI where required)
Step 6 – Capture everything in your report
- In your inspection report, create a dedicated section like “Valve Material Verification”.
- Summarise:
- Nameplate and marking checks,
- MTR review,
- Any equivalence assessment (EN vs ASTM),
- PMI or additional tests performed,
- Nonconformities and NCR numbers.
For structure and wording, Write a Valve Inspection Report (With Sample) and Vendor Inspection Reporting: IR/NCR/Final Dossier offer concrete examples.
Step 7 – Decide on disposition
- Accept valves where all documentation and checks are satisfactory.
- Accept under concession where a deviation is formally approved by design and the client.
- Reject or hold valves where material identity or documentation cannot be proven.
This workflow integrates naturally with the planning principles in Vendor Inspection ITP Template (Excel) + How to Use and Build an ITP & QCP for Vendor Surveillance.
5. How This Fits into NTIA’s Valve Inspection Toolkit
Valve nameplates, MTRs and material identification are not just admin tasks; they are core controls in NTIA’s approach to valve inspection and vendor surveillance.
On a typical project, this article connects directly with:
- Valve Inspection Checklist (PDF): Visual, Dimensional, Testing – detailed on-site checks per valve type.
- Hydrostatic vs Seat Leak Tests: Procedures & Acceptance – how pressure testing links back to the markings and standards on the nameplate.
- API 598 vs ISO 5208: Valve Testing Acceptance – to interpret test standards often shown on nameplates and certificates.
- Top 20 Valve Failure Modes & Root Causes – where material mix-ups and wrong markings regularly appear as underlying causes.
- EN 10204 3.1 vs 3.2: Differences Explained, MTC Interpretation Guide + Checklist (PDF) and EN vs ASTM: Common Material Specs Mapped – the documentation and material-spec side behind MTRs.
- PMI Testing: What, When & How to Document – the practical side of alloy verification in the shop and in the field.
Using these resources together gives you a complete NTIA inspection stack: from planning, to shop visits, to reporting and final dossiers.
6. Next Step with NTIA — Practise Valve Material Verification on Real Cases
If you want to move beyond reading checklists and actually practise valve material verification on real-world cases, join our course Industrial Valve Inspection & Testing Training.
In this hands-on program, NTIA trainers walk through:
- Live examples of valve FATs and vendor shop surveillance
- How to verify markings, MTRs and materials in line with API, ISO, EN and ASME requirements
- How to write inspection reports, IRs and NCRs that clearly document material verification and are easy for engineering and procurement to act on
You can learn more and register via Industrial Valve Inspection & Testing Training on the NTIA website.
7. FAQ — Nameplates, MTRs & Material Identification
Q1. What should I do if the valve nameplate material does not match the MTR?
Treat the valve as nonconforming until the discrepancy is explained. First, confirm that you are using the correct MTR (check heat number, standard and product description). If the mismatch remains, hold the valve, raise an NCR and ask the vendor for clarification or corrective action. Do not accept the valve based only on verbal assurances.
Q2. Is an EN 10204 Type 2.2 certificate acceptable when the spec calls for 3.1?
Usually not. EN 10204 Type 3.1 and 3.2 certificates provide a higher level of traceability and test evidence than 2.2. When the project specification requires 3.1/3.2, a 2.2 certificate should be treated as nonconforming unless a formal deviation or concession is approved.
Q3. Do all valves need PMI?
No. PMI is normally required for alloy steels, stainless steels, duplex and other critical services where the risk and consequence of material mix-up are high. Carbon steel valves in non-critical service may not need PMI. Always follow the project specification and the decision process in PMI Testing: What, When & How to Document.
Q4. How do I link an installed valve back to its MTRs?
Use the heat number and permanent markings on the body and bonnet. These should appear in the MTRs and in the manufacturer’s traceability records. On some projects, a valve serial number is also used to link the physical valve to a digital dossier of MTRs, test reports and inspection records.
Q5. Where in my inspection report should I document material verification?
Create a clearly titled section such as “Valve Material Verification & Documentation”. Summarise your checks on:
- Nameplates and markings
- MTRs and certificate types
- Any EN vs ASTM equivalence decisions
- PMI and additional tests
- NCRs raised and final dispositions
