What is Material Test Certificate, How to read an MTC?
A Material Test Report (MTC) is a quality assurance document generated by the mill manufacturer/process raw manufacturer and provided with the material to suppliers and fabricator. A material test certificate or MTC is an important document to ensure quality for a part. MTC shall be reviewed only by a competent person to ensure it meets the minimum requirements as per the material specification. Please see the type of inspection document click here.
Normally, a fabricator purchase material from a supplier who had stocked more types of materials and held the MTCs from the mill manufacturer. It is available for submission and review. So, you need to request them to send a sample MTC for review before shipping.
Refer to the MTC shown below for ASTM A312 TP 316/ 316L. The various locations on the information required to read an MTC are numbered in this MTC. Let’s understand each point so you can learn how to read & interpret an MTC.
Parts of a Material Test Certificates:
1. Manufacturer and type of inspection certificates who made product such pipe, tube, shape…
MTC shall state the company’s name or workshop, location, certificate compliance. Product markings: company’s name or company’s logo.
2. Trace number: also called heat number, ladder number (L), cast number.
The trace number shall trace to all the test results of chemical analysis results, mechanical test results, NDE test results, etc.Product markings: heat number or cast number.
3. Specifications and grades are a specification of material.
MTC shall be reported specification, grades, and year of edition. Product markings: specifications number and material grade.
4. Manufacture/ Delivery condition is a method of manufacture to form a production such as hot finish or cold finish, seamless or welded.
W Welded (RT or UT)
WX Welded (100% RT)
WU Welded (100% UT)
If RT/UT was performed for the welded seam, the inspection report should attach to MTC.
5. Dimensions: diameter, thickness is given in ASME B36.19M Tolerance of the wall thickness, see table 3.Product markings: size and thickness, example NPS 8” 20S
6. Weight: a mass per unit length.
If specified in the purchase order the marking for pipe larger than NPS 4 shall include the weight.
7. Mechanical properties: tensile strength, yield strength and percentage of elongation, see table 4.Product marking is not required
8. Chemical analysis:
See table 1, MTC may report heat analysis (H) and/or product analysis §.
Tolerance, see ASTM A999. The material requires may require to re-verify by Positive Material Inspection (PMI), you should note that PMI with or without carbon ( C ) content requirement, because it is affecting your cost, PMI with carbon ( C ) content is higher cost than without carbon content. Product marking is not required
9. Heat treatment: all stainless steel pipes shall be furnished in the heat treatment condition. After hot or cold working to size, then steel heated to ~1100°C.
Solution annealing is rapidly cooled by quenching into the water to prevent any carbides or other phases from forming.
Product marking is not required
10. Hydrotest or non-destructive test: Each pipe shall be subjected to the nondestructive electric test or the hydrostatic test.
Test pressure sees subsection 12 and subsection 22.2 in ASTM A999.
11. Supplementary: as specified in the purchase order such as PMI test, complied with NACE MR0175, Intergranular grain.
12. Stated and certified by mill signature: manufacturer statement of certification the product has been manufactured according to the specification and purchase order, etc., and endorsed by Quality department.