About Us
Eastern Steel Manufacturing Co.,Ltd is a leading manufacturer and distributor of seamless steel pipe, welded steel pipe, OCTG products and fittings. We supply first-step processing, semi-finished parts and finished parts to help our clients meet fabrication requirements beyond their capacity or to improve operations by moving forward the pre-production processing.
News
In this column you can find the steel pipe related articles you need, including industry trends, product standards and materials, and some technical guidelines.
Services
Eastern Steel Manufacturing Co.,Ltd not only improve product production and sales services, but also provide additional value-added services. As long as you need, we can complete your specific needs together.
Facility
Eastern Steel Manufacturing Co.,Ltd not only improve product production and sales services, but also provide additional value-added services. As long as you need, we can complete your specific needs together.
Projects
Many years of large-scale project experience in various fields（Oil & Gas, Construction, Power Energy, Marine & Offshore, Water Treatment, Exploration & Drilling Services, Pipeline & Petrochemical etc.）, professional project team is responsible from receiving until the end of the project.
In large-scale industrial projects (such as oil and gas, petrochemical, power plants, boilers, and high-rise building structures), the quality of the seamless steel pipe directly affects safety, lifespan, and project costs.
When purchasing seamless steel pipes, you will typically receive a Certificate of Conformity (MTC) issued by the factory. This document is the Material Test Report (MTR). It is not only a test document but also the "birth certificate" of the steel pipe, used to verify whether the product meets industry standards (such as API 5L, ASTM A106, or EN 10210) and the requirements of specific projects.
For engineers, quality control (QC) professionals, and purchasing teams, mastering the interpretation of MTCs is crucial—it ensures compliance, avoids high rework costs, and guarantees project safety.
MTC (Mill Test Certificate) certification is a quality certificate issued by the metal material manufacturer or a third-party testing organization, detailing the chemical composition, mechanical properties, and compliant standard requirements of the batch of materials. It is an important basis for material quality traceability and compliance acceptance, and is widely used in the fields of steel, pipes, flanges, and pressure vessels.
According to the international standard EN 10204, MTC reports are divided into four types: 2.1, 2.2, 3.1, and 3.2. Types 3.1 and 3.2 provide the most professional certification data and offer the most reliable evidence for determining the authenticity and quality of materials.
2.1: Non-specific inspection report issued by the supplier (no test data), suitable for low-risk general steel.
2.2: Report containing routine test results, for general structural steel.
3.1 (Most commonly used): Material data report issued by authorized inspectors of the manufacturer, showing formal testing results, suitable for pressure pipelines, boilers, and the oil and gas industry.
3.2 (Highest level): Joint certification by the manufacturer and third-party organizations (such as TUV, BV, LR), suitable for high-risk projects: nuclear power, subsea pipelines, and high-pressure vessels.
Although the format varies slightly among steel mills, most MTC reports include four non-negotiable parts. Skipping any of these parts can lead to misunderstandings:
|
Section |
Key Content |
Core Application Logic |
|
Header Information |
Pipe mill name, contact details, MTC number, date of issue, and customer name. |
Links the certificate to a specific order/batch (critical for traceability). |
|
Product Identification |
Seamless steel pipe sizes (OD × wall thickness), specifications (e.g., API 5L X65), heat number, and quantity. |
Confirms the certificate matches the pipes you received (avoid mix-ups). |
|
Test Results |
Chemical composition, mechanical properties, and additional tests (e.g., NDT, hydrostatic testing). |
Proves the pipe meets standard/ project requirements. |
|
Certification |
Signature of the mill’s authorized representative, and (if required) accreditation from a third-party body |
Validates the accuracy and authenticity of the test results. |
Develop the good habit of carefully checking that the heat number (a unique identifier for the metal batch) on the Metal Testing Certificate (MTC) matches the heat number engraved on the seamless steel pipe.
Check:
The Heat No. on the MTC
The Heat No. on the steel stamp/inkjet marking on the outer wall of the pipe
The Heat No. on the mill's Packing List
If a discrepancy is found, it indicates a problem with the product material. The factory should be contacted immediately to follow up, identify the cause, and develop a solution to minimize the adverse effects of the error.
The "Chemical Composition" section lists the percentages of elements such as carbon, manganese, and chromium in the seamless steel pipe. These factors directly affect the strength, corrosion resistance, and weldability of the steel pipe. Here's how to interpret it:
Common indicators include:
Carbon (C): Higher carbon content results in stronger corrosion resistance, but excessive carbon content can reduce weldability. In the API 5L X65 standard, the upper limit for carbon content is typically 0.22%.
Manganese (Mn): Improves toughness and corrosion resistance. ASTM A106 Class B (a commonly used seamless steel pipe for pressure applications) requires a manganese content between 0.27% and 0.93%.
Phosphorus (P) and Sulfur (S): Considered "impurities"—excessive content can cause the steel pipe to become brittle. Most standards limit the content of phosphorus and sulfur to 0.035% or less.
To improve the corrosion resistance of pipes, alloying elements are added. For example, in the ASTM A335 P91 standard, chromium (Cr: 8.0-10.5%) and molybdenum (Mo: 0.85-1.05%) are added to resist high temperatures and harsh environments.
Don't just look at the numbers; compare them to applicable standards or project specifications.
For example, if your project requires the use of API 5L X70 seamless steel pipe with a carbon content ≤ 0.20% (according to API 5L PSL2 standard), then a result of 0.23% indicates that the pipe does not meet the standard, even if it is very close.
When steel pipes are used in seawater, the sulfur content can be adjusted to improve corrosion resistance.
Typically, the sulfur content is reduced. The content is within this range (≤0.035% vs. ≤0.035%). 0.025% is optimal. When specifying a particular component content ratio, this custom requirement must be reflected in the MTC (Mechanical Properties Test).
The "Mechanical Properties" indicator is a crucial factor in measuring the performance of seamless steel pipes under pressure. This indicator is critical for projects involving pressure, weight, or temperature fluctuations. A deeper understanding of this indicator will benefit project management. Please focus on the following three key indicators.
|
Metric |
Definition |
How to Use It |
|
Yield Strength (YS) |
The stress at which the pipe begins to deform permanently. |
For high-pressure oil pipelines (API 5L X65), YS must be ≥448 MPa. If the MTC shows 430 MPa, the pipe can’t handle the design pressure. |
|
Tensile Strength (TS) |
The maximum stress the pipe can withstand before breaking. |
TS is often paired with YS—API 5L X65 requires TS ≥535 MPa. A TS/YS ratio <1.2 indicates poor ductility (risk of brittle failure). |
|
Elongation |
The percentage the pipe stretches before breaking (measures ductility). |
ASTM A106 Grade B requires ≥30% elongation. Low elongation (e.g., 25%) means the pipe may crack under sudden pressure changes. |
Professional Tip:
Pay Attention to "Average" vs. "Minimum".
Some steel mills report the "average" mechanical properties of a batch of steel pipes, but standards usually require each pipe to meet the minimum value.
For example, if the Material Testing Certificate (MTC) shows "average pressure: 450 MPa," but the API 5L X65 standard requires a minimum pressure of 448 MPa for each pipe, individual test results are needed—a single poorly performing pipe could jeopardize the entire system.
Hydrostatic Test: Checks pipe sealing.
NTD (UT/ET) Non-destructive Testing: Checks for cracks/inclusions.
Impact Test (Charpy V-notch): Low-temperature toughness (e.g., -20°C).
Dimensional Tolerance Testing: Outer diameter/wall thickness/ovality.
Hardness Testing (HB/HRC): Determines brittleness and heat treatment quality.
A Material Testing Certificate (MTC) is more than just a document; it's the foundation of a project's Quality Assurance (QA) program. Here are the reasons why an MTC is indispensable:
Without an MTC, it's impossible to prove that seamless steel pipes meet specifications.
For example, mistaking ASTM A53B pipe (low pressure) for A106B pipe (high pressure steam).
Most industries (oil and gas, nuclear, etc.) have stringent regulations requiring documentation of material quality.
In the United States, the Piping and Hazardous Materials Safety Administration (P
HMSA) mandates that all pipelines transporting hazardous fluids must obtain MTC certification.
If a problem occurs with seamless steel pipes (such as pressure cracking), an MTC (Mechanical Traceability Inspection) can help determine the root cause.
In the event of cracks or pipe bursts, the MTC can quickly pinpoint the furnace responsible.
Provides key chemical composition and mechanical property parameters for subsequent processing (such as welding, heat treatment, and cold bending).
When questions arise about material quality or quality incidents occur, the MTC report serves as primary verification and legal evidence.
Check if the manufacturer's name and address match the contract information.
Verify that the batch number matches the physical identification (such as stamps and labels).
Compare the chemical composition with standard requirements to determine if it is within the allowable range.
Check if the mechanical properties match the material grade reasonably.
For high-risk projects, it is recommended to choose MTC 3.1 or 3.2 certification to ensure data accuracy.
If the certificate indicates a third-party organization (such as TUV, BV), verify with their official channels.
Some manufacturers add QR codes and anti-counterfeiting codes to the MTC (Mill Test Certificate), which can be verified directly online.
In most oil and gas, pressure pipelines, boilers, and power engineering projects, the MTC is a mandatory document.
It is not mandatory in general building structures, but it is still recommended to provide it to ensure traceability.
The rolling tolerance for seamless steel pipes is typically ±12.5%, as specified by mainstream standards such as API 5L, ASTM A106, and ASTM A53.
The MTC (Mill Test Certificate) serves as an important proof of material quality. It not only verifies whether the metal material meets standards but also effectively prevents counterfeit and substandard products from entering the market. Interpreting a seamless steel pipe material inspection certificate involves verifying the consistency of the heat number, ensuring that the chemical composition and mechanical properties meet specifications, and confirming that the testing has been completed. If any questions arise—such as a missing signature or values that are "close but not acceptable"—please contact the steel mill immediately.
E-mail: sales@eastern-steels.com
