JRVAL
Aug 07 2025THE ULTIMATE GUIDE TO
BUTTERFLY VALVE MATERIAL & CERTIFICATION
In the world of industrial fluid control, a butterfly valve is more than its design; it is the sum of its materials. The longevity, safety, and reliability of a valve are not determined by its shape, but by the fundamental integrity of the alloys and polymers from which it is forged. A seemingly perfect valve cast from the wrong material is a failure waiting to happen. A leak, a rupture, or a premature degradation can lead to catastrophic consequences: production downtime, environmental damage, and unacceptable safety risks.
ARCHIVE TABLE OF CONTENTS
1.0 Core Concepts
2.0 Component Material Standards
3.0 Performance-Driven Materials
4.0 MTR Analysis
1.0 INTRODUCTION & FUNDAMENTAL CONCEPTS
1.1 What is Material Certification?
A Material Test Report (MTR), often called a Mill Test Report or a Certified Mill Test Report (CMTR), is a quality assurance document that certifies a material's chemical and physical properties. It is the material's "birth certificate," tracing its journey from raw elements to a finished product with specific, measured characteristics. An MTR provides the objective data needed to confirm that the material meets the requirements of a given standard (e.g., ASTM A216 WCB).
1.2 The Global Language of Material Certification: EN 10204
Before we can discuss specific materials, we must understand the system that guarantees their properties. In the global supply chain, trust cannot be based on a verbal promise. It must be based on documented, verifiable evidence. The European Standard EN 10204 provides the universally accepted framework for this evidence, defining the different types of inspection documents that a material manufacturer can provide.
Type 2.1: Declaration of Compliance
Definition: This is the most basic level. The manufacturer simply declares, without providing any test results, that the products supplied are in compliance with the requirements of the order. It is a statement of compliance, not a proof of properties.
Validation: Issued by the manufacturer. No test results are included.
Application: Non-critical, low-risk components where basic affirmation is sufficient.
Type 2.2: Test Report
Definition: The manufacturer affirms compliance and provides test results to prove it. However, these results are based on non-specific inspection. This means the tests were conducted as part of routine quality control, and the results may not be from the exact batch of material being supplied. It shows that the manufacturing process is capable of producing compliant material.
Validation: Issued by the manufacturer. "Non-specific" means the tests were carried out on products made by the same process, but not necessarily from the exact batch being delivered.
Application: Moderate-risk applications requiring general proof of properties.
Type 3.1: Inspection Certificate
Definition: This is the most common and widely accepted type for pressure-retaining components. The manufacturer provides test results from specific inspection, meaning the tests were performed on samples taken from the actual batch (or "heat") of material being delivered. This certificate is validated by the manufacturer's authorized inspection representative, who must be independent of the manufacturing department. This directly links the supplied product to its certified properties.
Validation: Issued by the manufacturer's authorized inspection representative who must be independent of the manufacturing department. "Specific" means the tests were performed on the actual products being supplied.
Application: The industry standard for all pressure-retaining parts and critical components.
Type 3.2: Inspection Certificate
Definition: This provides the highest level of assurance. The requirements are the same as for Type 3.1, but the certificate is additionally validated by either the purchaser's authorized representative or an independent third-party inspector (e.g., from Lloyd's, DNV, TUV). This is typically required for the most critical applications, such as nuclear power or high-pressure offshore platforms, where an independent witness of the testing process is non-negotiable.
Validation: Co-signed by the manufacturer's independent rep AND the purchaser's authorized rep or an inspector designated by official regulations (e.g., TÜV, DNV, Lloyd's).
Application: The highest level of assurance, reserved for the most critical services (nuclear, offshore, lethal service).
1.3 Quick-Reference: Which Certificate Type Do You Need?
Choosing the right certificate type is a balance of risk, cost, and regulatory requirements. This table provides a general guideline.
| Certificate Type | Key Feature | Typical Application | Validated By |
|---|---|---|---|
| EN 10204 Type 2.1 | Declaration of compliance only | Non-critical components, general hardware | Manufacturer |
| EN 10204 Type 2.2 | Results from non-specific inspection | Less critical applications, structural parts | Manufacturer |
| EN 10204 Type 3.1 | Results from the actual supplied batch | Standard for all pressure-retaining parts (body, disc) | Manufacturer's independent representative |
| EN 10204 Type 3.2 | Type 3.1 witnessed by a third party | Nuclear, offshore, critical process systems | Manufacturer's rep + Purchaser's rep or 3rd Party |
2.0 COMPONENT MATERIAL STANDARDS & CERTIFICATION REQUIREMENTS
A butterfly valve is an assembly of precisely engineered components, each with a distinct role and subject to different stresses. Therefore, material selection is not a one-size-fits-all decision. It is a nuanced process tailored to each component, balancing mechanical strength, corrosion resistance, temperature tolerance, and cost. This section dissects the most common material choices for each critical part of the valve.
2.1 Body Materials
The body is the valve's foundation and primary pressure boundary. Its material dictates the valve's overall pressure-temperature rating and its suitability for the external environment and internal fluid.
| Material Category | Specific Grade / Type | Primary International Standards (ASTM, EN, DIN, JIS, GB) | Certification & Engineering Notes |
|---|---|---|---|
| Cast Iron | Grey Cast Iron | ASTM A126 Cl.B, EN 1561 (EN-GJL-250), DIN GG25, JIS FC250, GB/T HT250 | Lowest cost. For general utility services (water, air). Limited strength and ductility. Typically requires EN 10204 2.2. |
| Ductile Iron (Nodular) | ASTM A536 Gr. 65-45-12, EN 1563 (EN-GJS-400-15/GGG40), JIS FCD450, GB QT450-10 | Superior strength and ductility over grey iron. Industry standard for general industrial applications. EN 10204 3.1 often required. | |
| Carbon Steel (Cast) | Standard Service | ASTM A216 Gr. WCB/WCC, EN 10213 (GP240GH), DIN GS-C25, JIS SCPH2 | The workhorse for industrial processes. Good strength, machinability. Mandatory EN 10204 3.1 for PED/ASME. |
| Low-Temperature Service | ASTM A352 Gr. LCB/LCC | For cryogenic applications. Requires Charpy V-Notch impact testing at low temperatures, which must be on the MTR. | |
| Stainless Steel (Cast) | Austenitic SS | ASTM A351 Gr. CF8 (304), CF8M (316), CF3 (304L), CF3M (316L) | Excellent corrosion resistance. CF8M (316) is standard for chemical service. L-grades (CF3/CF3M) prevent carbide precipitation after welding. |
| Duplex SS | ASTM A890/A995 Gr. 4A (CD3MN), 5A (CE3MN) | Superior strength and chloride stress corrosion cracking resistance compared to austenitic SS. Common in marine and processing industries. | |
| Super Duplex SS | ASTM A890/A995 Gr. 6A (CD3MWCuN) | Enhanced performance over standard duplex, for highly corrosive environments (e.g., high chloride, sour service). | |
| Alloy Steel (Cr-Mo) | High-Temperature Service | ASTM A217 Gr. WC6, WC9, C5, C12A (F91) | For high-temperature and high-pressure steam, hydrocarbon service. Heat treatment condition is critical and must be on the MTR. |
| Non-Ferrous & Special Alloys | Aluminum Bronze | ASTM B148 C95800 | Excellent for seawater and marine applications due to high resistance to biofouling and corrosion. |
| Monel | ASTM A494 M35-1 (Monel 400) | Resists hydrofluoric acid and many reducing media. Often used in alkylation units and marine environments. | |
| Hastelloy | ASTM A494 CW6M (C22), CW2M (C276) | Exceptional resistance to a wide range of aggressive chemicals, including oxidizing and reducing acids. | |
| Inconel | ASTM A494 CY40 (Inconel 600), CW6MC (Inconel 625) | For extreme temperature (high and cryogenic) and corrosive environments. Retains high strength at elevated temperatures. | |
| Titanium | ASTM B367 Gr. C2, C3 | Highest strength-to-weight ratio. Nearly immune to seawater, chlorine, and many chemical services. | |
| Lined Body | PTFE, PFA, Rubber (EPDM, NBR) | Base Metal (Ductile Iron or WCB) + Liner Material | Requires TWO sets of certifications: 1) EN 10204 3.1 MTR for the base metal casting. 2) Certificate of Conformity for the liner material, often with specific approvals like FDA or WRAS. |
2.2 Disc Materials
The disc is the primary flow control element and is in constant contact with the fluid. Its material must be compatible with the media and resistant to erosion. While the disc material often matches the body, it is common to upgrade the disc for better performance or use a coated disc for economy.
| Material Category | Specific Grade / Type | Primary International Standards (ASTM, EN, DIN, JIS, GB) | Certification & Engineering Notes |
|---|---|---|---|
| Bare Metal Disc | Stainless Steel | ASTM A351 CF8M (316), ASTM A276 Type 316, Duplex 2205 (S32205), Super Duplex 2507 (S32750) | Disc material must be equal or superior to body material for corrosion resistance. Polished surfaces are often required. |
| Special Alloys | Monel, Hastelloy, Titanium (Standards per section 2.1.5) | Chosen when the disc is the primary wetted part and requires extreme corrosion resistance. | |
| Coated / Encapsulated Disc | Base Metal | Ductile Iron (ASTM A536), Carbon Steel (ASTM A216 WCB) | Requires EN 10204 3.1 MTR for the metallic substrate. |
|
Coating / Liner
|
Nylon 11/12, Halar (ECTFE), Epoxy, Rilsan®, PTFE, PFA |
(For many utility services,a Ductile Iron disc coated with Nylon, RPTFE, or Halar® (ECTFE) provides excellent corrosion resistance at a lower cost than a solid alloy disc.) Requires Certificate of Conformity for the coating material, plus reports for coating thickness, adhesion (pull-off test), and holiday (spark) testing. |
The material options for solid discs are largely the same as for the body, with a strong emphasis on corrosion and erosion resistance. Grades like CF8M, Duplex (2205), Aluminum Bronze (C95400/C95800), and Hastelloy C276 are very common choices.
2.3 Stem Materials
The stem must transmit torque from the actuator to the disc, so high tensile strength is paramount. As a wetted part, it also requires excellent corrosion resistance. Stem material is a critical specification that should never be overlooked.
| Material Type | Specific Grade / Type | Primary International Standards (ASTM, EN, DIN, JIS, GB) | Certification & Engineering Notes |
|---|---|---|---|
| Stainless Steel | Martensitic / PH SS | ASTM A276 Type 410, 420; ASTM A564 Type 630 (17-4PH) | High strength for torque transmission. 17-4PH is the industry benchmark, providing excellent strength and good corrosion resistance. Heat treatment condition (e.g., H1150) is critical. |
| Austenitic SS | ASTM A276 Type 304, 316 | Better corrosion resistance but lower strength than martensitic grades. Used in less demanding or highly corrosive services. | |
| Special Alloys | High Strength/Corrosion | Monel K500 (ASTM B865), Inconel 625, Hastelloy C276 | For services where combined high strength and extreme corrosion resistance are mandatory. Monel K500 is age-hardenable. |
2.4 Seat & Seal Materials (The Heart of the Valve)
For soft-seated butterfly valves, the seat provides the shutoff capability. Its material compatibility with the fluid and temperature is the single most important factor for valve performance and longevity.
| Material (Abbr.) | Common Name / Trade Name | Typical Temp. Range | Key Characteristics & Common Applications |
|---|---|---|---|
| EPDM | Ethylene Propylene Diene Monomer | -40°C to 120°C | Excellent for water, steam, and alcohols. Not suitable for hydrocarbon oils or solvents. Most common choice for HVAC and water treatment. |
| NBR | Nitrile / Buna-N | -20°C to 100°C | Excellent resistance to oils, fuels, and petroleum-based hydraulic fluids. The standard choice for POL (Petroleum, Oils, Lubricants) applications. |
| FKM / FPM | Viton® (Chemours trade name) | -20°C to 200°C | Excellent resistance to a wide range of chemicals, acids, and high temperatures. Not good for steam. Used in chemical processing and hydrocarbon industries. |
| PTFE | Polytetrafluoroethylene | -50°C to 200°C | Nearly universal chemical inertness. Low friction. Prone to cold flow (deformation). Often used as a liner or with a reinforcing filler (RPTFE). |
| SIL | Silicone | -60°C to 200°C | Excellent temperature range, good for food grade applications and air. Poor tear and abrasion resistance. |
| CSM | Hypalon® (former trade name) | -30°C to 125°C | Good resistance to acids, alkalis, and weathering. Used in chemical and pulp & paper industries. |
| UHMWPE | Ultra High Molecular Weight Polyethylene | -70°C to 90°C | Exceptional abrasion resistance. Used for slurries, mining, and bulk material handling. |
2.5 Fastener (Bolting) Materials
The materials for the bolts and nuts that hold the valve together (especially for lug or two-piece body styles) or mount it to the pipeline are governed by standards like ASTM. Proper material choice prevents corrosion and ensures mechanical integrity.
| Grade | Standard | Material Type | Common Use Case |
|---|---|---|---|
| B7 (Studs/Bolts); 2H (Nuts) | ASTM A193 (Bolts); ASTM A194 (Nuts) | Quenched & Tempered Alloy Steel | The most common combination for industrial applications with carbon or alloy steel valves. B7M/2HM are for sour service (NACE) and require 100% hardness testing. |
| B8/B8M (Bolts); 8/8M (Nuts) | ASTM A193 (Bolts); ASTM A194 (Nuts) | Stainless Steel (304 / 316) | Used with stainless steel valves to prevent galvanic corrosion and for corrosive environments. B8M/8M is paired with 316/CF8M valves. |
2.6 Surface Coatings & Linings
Coatings are applied to less-resistant base materials (like cast iron) to provide protection against corrosion or abrasion. This is often a more economical solution than using a solid alloy body.
Fusion Bonded Epoxy (FBE)
A thermoset polymer coating, typically applied at 200-300 microns (µm) thickness. It is the industry standard for protecting cast/ductile iron valve bodies in water, wastewater, and buried service applications. Provides excellent corrosion resistance.
PTFE Lining
A thick (typically 3mm) lining of PTFE is applied to the interior of a valve body. This allows a low-cost body material to handle extremely corrosive chemicals, as only the PTFE liner and a suitable disc/stem are exposed to the media.
Nylon 11 Coating
Offers good chemical resistance and excellent abrasion resistance, making it suitable for mildly abrasive slurries.
3.0 PERFORMANCE-DRIVEN MATERIAL REQUIREMENTS & STANDARDS
Standard material selections are sufficient for general-purpose applications. However, when a valve is placed into a hazardous, extreme-temperature, or environmentally sensitive service, its materials must meet a higher level of scrutiny, governed by performance-based standards. These standards don't just define what a material is, but what it must endure.
3.1 | Sour Service (H₂S) Environments: NACE MR0175 / ISO 15156
The Hazard: Hydrogen Sulfide (H₂S) can cause catastrophic Sulfide Stress Cracking (SSC) in susceptible steels. Standard high-strength steels can become brittle and fracture without warning.
The Standard: NACE MR0175 / ISO 15156 is the global standard specifying material requirements for H₂S environments. It provides a list of pre-qualified materials and defines acceptable conditions (temperature, hardness, heat treatment).
Key NACE Considerations:
Hardness Control: The primary requirement is controlling material hardness, typically to a maximum of 22 HRC for carbon/low-alloy steels, requiring specific heat treatments.
Compliant Materials: Austenitic grades like SS 316, Duplex steels, and high-nickel alloys (Monel, Inconel) are commonly used for their inherent resistance. An MTR must explicitly state NACE compliance and report measured hardness values.
3.2 | Low-Fugitive Emission Service: API 624 & ISO 15848
The Goal: To prevent the leakage of volatile, hazardous, or greenhouse gases into the atmosphere, a major concern for environmental protection (EPA) and plant safety.
The Standard: API 624 & ISO 15848 define a rigorous type-testing procedure. A valve design is subjected to thousands of mechanical and thermal cycles while stem leakage is measured. To pass, leakage must stay below a defined threshold (e.g., 100 ppmv).
The Solution is in the Packing:
High-Integrity Packing: Performance is almost entirely dependent on the stem packing. High-Purity Flexible Graphite is the cornerstone material, die-formed into high-density rings. These sets are engineered with multiple rings and "live-loaded" with Belleville springs to maintain constant pressure.
3.3 | Fire-Safe Design: API 607
The Scenario: A plant fire engulfs the valve, destroying its primary soft, resilient seat (e.g., PTFE). The valve must still limit leakage to prevent feeding the fire.
The Standard: API 607 defines fire-testing requirements. The valve is subjected to a fire, and after soft seals are destroyed, it must still limit leakage to an acceptable rate.
Key Design Features:
Secondary Metal Seat: A fire-safe butterfly valve has a secondary, integral metal seat. After the soft seat burns away, the metal disc creates a metal-to-metal seal against the body.
Graphite Seals: Graphite is critical. It withstands extreme temperatures and is used for body seals and stem packing to ensure the valve's pressure boundary remains sealed even after a fire.
3.4 | Cryogenic Service: BS 6364
The Challenge: At cryogenic temperatures (below -50°C), standard carbon steels become brittle and can shatter. Elastomers lose flexibility and sealing ability.
The Standard: BS 6364 specifies design, material, and testing for cryogenic valves.
Key Material Requirements:
Toughness: Only materials that retain toughness at low temps can be used, primarily Austenitic Stainless Steels (316/CF8M). They require Charpy V-Notch impact testing at the minimum design temperature, reported on the MTR.
Extended Bonnet: Valves feature a long bonnet to move stem packing and the actuator away from the extreme cold, ensuring they remain operational.
3.5 | Potable Water & Food Grade Service: NSF/ANSI 61, WRAS, FDA
The Requirement: Materials in contact with drinking water or food must not leach harmful chemicals or impart any unwanted taste or odor.
The Standards: NSF/ANSI/CAN 61 (North America drinking water), WRAS (UK water), and FDA (US food contact) govern these applications.
Material Focus:
Certified Elastomers & Coatings: The focus is on non-metallic components. Seat materials like EPDM and NBR, and coatings like FBE, must be from a special, certified compound that has passed rigorous extraction tests defined by the standard.
Traceability: A certified valve must be built using only approved materials from approved suppliers, with full traceability maintained.
4.0 HOW TO INTERPRET & VERIFY A MATERIAL TEST REPORT (MTR)
A Material Test Report is the legal and technical backbone of component integrity. It is not merely a document to be filed, but a dataset to be critically analyzed. This chapter deconstructs the MTR and provides a rigorous checklist for its validation, empowering you to identify compliant, questionable, or fraudulent documentation.
4.1 Anatomy of an MTR: A Structural Analysis
A compliant MTR is structured to provide unambiguous information. Below is a breakdown of its essential sections. Every field must be present and legible.
4.1.1 Header & Order Information
This section links the document to a specific transaction.
• Key Data: Manufacturer's Name & Address, Certificate Number (unique), Purchaser's Name, Purchase Order (PO) Number.
• Verification Point: Does the PO number on the MTR match your official purchase order? Is the manufacturer the one specified?
4.1.2 Traceability Identifier: Heat Number
This is the single most critical piece of information on the MTR. The Heat Number (or Melt/Cast No.) is a unique code assigned to a single batch of molten metal. Every component forged or cast from that batch will carry this number.
• Verification Point: This number MUST be physically and permanently marked (stamped, etched) on the valve body/component and must match the MTR exactly. One MTR per heat number.
4.1.3 Specification & Grade
This section defines the "rulebook" the material was made to follow.
• Key Data: The material standard (e.g., ASTM A216), the specific grade (e.g., WCB), and the year of the standard's revision.
• Verification Point: Does this match the specification on your PO? An MTR for "Carbon Steel" is insufficient; it must state the exact standard and grade.
4.1.4 Chemical Composition Analysis
Lists the elemental composition of the heat. It typically shows the specified range from the standard and the actual measured value for the heat.
• Key Elements: C, Mn, P, S, Si for Carbon Steel; Cr, Ni, Mo for Stainless/Alloy Steels.
• Verification Point: Check that EVERY measured value falls within the specified min/max range. Pay close attention to Carbon Equivalent (CE) if listed.
4.1.5 Mechanical Properties
This proves the material's physical performance.
• Key Properties: Tensile Strength, Yield Strength, Elongation (ductility), Reduction of Area. For specific applications: Hardness (Brinell HB, Rockwell HRC) and Impact Toughness (Charpy V-Notch Joules @ a specific temperature).
• Verification Point: All tested values must meet the standard's minimum (or be within the required range). Hardness is critical for NACE compliance.
4.1.6 Heat Treatment
The thermal process used to achieve the final mechanical properties.
• Key Data: The process type (e.g., Normalize & Temper, Quench & Temper, Solution Anneal), temperature, and holding time.
• Verification Point: Is the specified heat treatment correct for the material grade (e.g., WCB must be normalized)? This is a common point of failure/non-compliance.
4.1.7 NDT & Supplemental Tests
Reports on Non-Destructive Testing if required by the PO or standard.
• Key Data: Statements of compliance for Radiographic (RT), Ultrasonic (UT), Magnetic Particle (MT), or Dye Penetrant (PT) tests.
• Verification Point: If your PO required "100% UT," the MTR must explicitly state that this was performed and that the results were acceptable.
4.1.8 Compliance Statement & Signature
The final declaration and authorization.
• Key Data: A clear statement that "the material has been tested and complies with [Standard]" and the signature/stamp of the authorized Quality Control department representative.
• Verification Point (EN 10204 3.1): The signing department must be independent of production. A 3.2 cert will have a second stamp from the third-party inspector.
4.2 The Verification Checklist: From Procurement to Acceptance
Use this five-step process for every critical component you receive.
1. Physical Traceability Check
Action: Take the MTR to the physical valve. Locate the Heat Number stamped or etched on the valve body (and sometimes disc/stem).
Pass/Fail: Does the number on the MTR exactly match the number on the component? If not, the component is undocumented and must be rejected. No exceptions.
2. Data Compliance Audit
Action: With the relevant material standard (e.g., ASTM A216) in hand, compare every chemical and mechanical value on the MTR against the standard's required ranges.
Pass/Fail: Is every single value within its specified limit? An "almost" or "close enough" is a failure.
3. Certificate Type Validation
Action: Review your original purchase order. What certification type did you specify? (e.g., EN 10204 3.1).
Pass/Fail: Does the document received explicitly state it is the type you requested? Receiving a 2.2 when you ordered a 3.1 is a major non-conformance.
4. Issuer Independence Check (for 3.1)
Action: Examine the signature/stamp on the 3.1 certificate. It must be from a department that is functionally independent of manufacturing (e.g., Quality Control, Quality Assurance, Laboratory).
Pass/Fail: If the MTR is signed by the "Production Manager," it fails the independence requirement and is not a valid 3.1 certificate.
5. Third-Party Endorsement (for 3.2)
Action: If a 3.2 certificate was required, look for two distinct signatures/stamps. One from the manufacturer's independent rep, and a second one from the designated third-party inspector (e.g., Lloyd's, DNV, TÜV) or the purchaser's inspector.
Pass/Fail: The absence of the verified, independent third-party endorsement invalidates a 3.2 certificate.
5.0 APPENDICES, DATA & CONCLUSION
This final chapter provides high-density reference tables for rapid material grade comparison and certification analysis. It concludes with a critical review of common MTR discrepancies and a final statement on the non-negotiable importance of rigorous material certification.
APPENDIX A: GLOBAL MATERIAL GRADE EQUIVALENCY TABLE
Material specifications vary by region. This table provides a non-exhaustive but highly practical cross-reference for common cast valve body materials across major international standards. Note: While these grades are generally considered equivalent, always refer to the specific standard's text for exact chemical and mechanical requirements, as minor differences may exist.
| Material Type | ASTM (USA) | EN (Europe) | DIN (Germany) | JIS (Japan) | GB (China) |
|---|---|---|---|---|---|
| Carbon & Low-Temp Steels | |||||
| Standard Carbon Steel | A216 WCB | EN 10213 GP240GH | 1.0619 (GS-C25) | SCPH 2 | ZG250-485 |
| Low-Temp Carbon Steel | A352 LCB | EN 10213 G17Mn5 | 1.6220 (GS-21Mn5) | SCPL 1 | ZG20Mn |
| Austenitic Stainless Steels | |||||
| SS 304 Equivalent | A351 CF8 | EN 10213 1.4308 | G-X6CrNi18-9 | SCS 13A | ZG0Cr18Ni9 |
| SS 316 Equivalent | A351 CF8M | EN 10213 1.4408 | G-X6CrNiMo18-10 | SCS 14A | ZG0Cr17Ni12Mo2 |
| SS 316L Equivalent | A351 CF3M | EN 10213 1.4409 | G-X2CrNiMo19-11-2 | SCS 16A | ZG00Cr17Ni14Mo2 |
| High-Strength & Duplex Steels | |||||
| Duplex Stainless Steel | A890/A995 Gr. 4A | EN 10213 1.4470 | G-X2CrNiMoN22-5-3 | SCS 10 | ZG1Cr25Ni5Mo1.5 |
| Super Duplex SS | A890/A995 Gr. 5A | EN 10213 1.4501 | G-X2CrNiMoCuN25-6-3-3 | SCS 11 | 00Cr25Ni7Mo4N |
| Alloy Steels (High Temperature) | |||||
| 1-1/4Cr-1/2Mo Steel | A217 WC6 | EN 10213 G17CrMo5-5 | 1.7357 (GS-17CrMo5-5) | SCPH 21 | ZG20CrMo |
| 2-1/4Cr-1Mo Steel | A217 WC9 | EN 10213 G17CrMo9-10 | 1.7379 (GS-17CrMo9-10) | SCPH 32 | ZG15Cr1Mo1V |
APPENDIX B: Chemical Compatibility Chart for Seat Materials (Simplified)
This chart is a general guide only. The concentration of the chemical, operating temperature, and specific compound of the elastomer can significantly affect performance. Always consult a detailed chemical compatibility chart from the manufacturer for your specific application.
| Media | EPDM | NBR (Nitrile) | FKM (Viton®) | PTFE |
|---|---|---|---|---|
| Water / Steam | Excellent | Poor | Poor | Excellent |
| Oils / Gasoline | Poor | Excellent | Excellent | Excellent |
| Ketones (e.g., Acetone) | Poor | Poor | Poor | Excellent |
| Strong Acids | Fair | Poor | Excellent | Excellent |
| Chlorinated Solvents | Poor | Poor | Fair | Excellent |
| Sunlight / Ozone (Weather) | Excellent | Poor | Excellent | Excellent |
APPENDIX C: COMMON MTR PITFALLS & RED FLAGS
A document is only as good as its accuracy. Be vigilant for these common errors and signs of falsification, which can invalidate a certification and compromise safety.
Mismatched Heat Numbers
The heat number on the MTR does not match the number physically stamped on the valve. This is the most severe red flag. It breaks traceability, rendering the MTR useless for that component. The part must be rejected.
Out-of-Specification Values
A chemical element (e.g., Carbon, Sulfur) or mechanical property (e.g., Yield Strength) is outside the limits defined by the material standard. Even a minor deviation is a non-conformance.
Incorrect Certificate Received
The Purchase Order specifies EN 10204 3.1, but the supplier provides a 2.2 certificate. This is a common cost-cutting tactic. A 2.2 does not provide specific test results for the delivered batch and is not a valid substitute.
Missing or Vague Information
The MTR omits critical data required by the standard, such as heat treatment details (e.g., "Heat Treated" is not enough; it must state the process and temperature), or impact test temperature.
Questionable Authenticity
The document shows signs of alteration: different fonts, misaligned text, photocopied stamps, or pixelation. In the digital age, always request the original PDF from the manufacturer, not a scan from a downstream supplier.
Footnote Abuse / Extrapolation
The MTR contains data that is not from direct measurement of the heat but is "typical" or "guaranteed by process." While sometimes acceptable for non-critical values, key properties for high-pressure service must be from specific testing of that heat.
CONCLUDING STATEMENT
Material certification is the foundation of industrial safety and reliability. A butterfly valve is not merely a commodity; it is a complex assembly of engineered materials designed to operate under specific, often extreme, conditions. The Material Test Report is the only objective proof that this design intent has been met. Scrutinizing this documentation with the rigor outlined in this archive is not a procedural formality—it is a core engineering responsibility. Failure to do so introduces unacceptable risk. Trust, but always verify.
FEEDBACK & SUGGESTIONS
Did you find this guide useful? Do you have suggestions for improvement or topics you'd like to see covered? We value your expert opinion. Please leave a comment below.
Recent Feedback
John D.
Posted on 08 August, 2025
This is an incredibly comprehensive guide. Appendix A is a lifesaver for cross-referencing global standards. Could you perhaps add a section on fugitive emissions testing like ISO 15848-1?