ASTM A312 - material inspection

What is a Material Test Report?

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. Please see type of inspection document.


Normally, a fabricator purchase material from supplier who had stocked more type of materials and held the MTCs from mill manufacturer. It is available for submission and reviewing. So, you need to request them to send a sample MTC for review before shipping, it also avoid misunderstanding the requisition in PO and restriction of Approval’s Vendor List. Approval’s Vendor List is listed the mill manufacturer/ mill processor of some global company like TechnipFMC, Petronas, UOP, etc which limits in the specifications like country of origin, supplementary, inspection document, etc.

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ASTM A312 / A312M – Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes.

Material inspection and review its MTC are a cope of welding inspector that how to accept or reject when received MTC from supplier.
A lot of issue found when material delivery out, MTC come later such wrong heat number, wrong MTC, not comply with purchase order,…So, you should request to send MTC for reviewing before delivery.

1. Manufacturer and type of inspection certificates

who made product such pipe, tube, shape…
MTC shall state 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

The specification of material.
MTC shall be reported specification, grades and year of edition.

Product markings: specifications number and material grade.

4. Manufacture/ Delivery condition

Method of manufacture to form a production such hot finish or cold finish, seamless or welded.

Abbreviation Marking
SMLS Seamless
W Welded (RT or UT)
WX Welded (100% RT)
WU Welded (100% UT)

If RT/UT was performed for welded seam, the NDT report shall stated on the MTC.

5. Dimensions

Diameter, thickness are given in ASME B36.19M
Tolerance of the wall thickness, see table 3.
Product markings: size and thickness, example NPS 8” 20S

6. Weight

Mass per unit length.
If specified in 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.

Material require 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 effected 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 water to prevent any carbides or other phases 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 see subsection 12 and subsection 22.2 in ASTM A999.

  • NH: when hydrotesting is not performed.
  • ET: when eddy-current test is performed.
  • UT: when ultrasonic test is performed.

Product marking is NH, ET or UT.

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 accordance to the specification and purchase order, etc. and endorsed by Quality department.



How I do? if my vendor miss a RT report.

Request Vendor/ Manufacturer send back a RT report because each company they have recorded to trace number.


:boom: ASTM A312A312M 2019 :white_check_mark: