How to Read a Mill Test Certificate (MTC) ?

When reading an MTC for an A105N flange, you should pay close attention to the following key sections:

1. توضیحات محصول

   • This includes the product name (e.g., A105N weld neck flange), size, pressure rating (e.g., 6″ 150#), standard (e.g., ASME B16.5), type (e.g., WN for weld neck), heat number, quantity, and weight. These details should match the items being supplied.

2. تعیین مواد

   • Check that the material is listed as ASTM A105N, where “N” indicates that the material has been normalized, enhancing its toughness at low temperatures.

3. ترکیب شیمیایی

   • This section provides the actual chemical analysis values of the material. It should list the content of elements such as Carbon (C), Manganese (Mn), Phosphorus (P), Sulfur (S), Silicon (Si), and others (e.g., Cr, Mo, Ni, Cu).

   • Compare the actual values with the specified limits in ASTM A105 to ensure compliance.

4. خواص مکانیکی

   • Important mechanical test results such as:

     • استحکام کششی (Minimum: 485 MPa / 70 ksi)

     • قدرت تسلیم (Minimum: 250 MPa / 36 ksi)

     • ازدیاد طول (Minimum: 22% for round specimens)

     • کاهش مساحت

   • These values must meet or exceed the requirements of ASTM A105.

5. عملیات حرارتی

   • It should clearly state that the material has undergone normalizing. This is usually written as “Normalized” or “Heat treated: Normalized.”

6. Impact Test (if applicable)

   • If required for low-temperature applications, impact test results (Charpy V-Notch) will be included. Typically tested at -46°C for A105N flanges used in cold environments. Values should meet specified energy absorption criteria.

7. Heat Number

   • This is a unique identifier that links the MTC to the specific batch of material. It should be traceable and also marked on the flange body.

8. Standards and Specification Compliance

   • The MTC should state conformance to relevant standards such as:

     • ASTM A105N for material

     • ASME B16.5 for flange dimensions

     • ASME B31.3 یا ASME Section VIII if referenced

     • EN 10204 Type 3.1 for the MTC format (if applicable)

9. Manufacturer Information

   • The name, logo, or official stamp of the manufacturer should appear on the certificate, including:

     • Company name

     • Country of origin

     • Signature of quality inspector

     • Date of issue

10. Additional Remarks

    • May include heat treatment remarks, NDE (Nondestructive Examination) results, hydrostatic test info, dimensional inspection results, etc.