Details determine success or failure in any precision engineering or manufacturing project. For customers using stainless steel plates, a detail that is often asked but is crucial is the thickness tolerance.
Is the actual thickness of the 10mm thick steel plate you ordered really 10.00mm? How much deviation is allowed?
The answer to this question is directly related to your project cost, structural safety, and final processing quality. The authoritative document that regulates all of this is the ASTM A480 standard.
As an industry-leading stainless steel supplier, Huaxiao Stainless Steel often answers such questions for customers. Therefore, we have written this detailed guide to demystify ASTM A480 and help you become a more professional buyer.
What is ASTM A480?
ASTM A480/A480M is a standard specification issued by the American Society for Testing and Materials (ASTM International). Its full name is “Standard Specification for Plate, Strip and Sheet of Stainless and Chromium Steels for Pressure and General Purposes, Heat and Corrosion Resistant”.
In short, it is the general requirements for dimensions, tolerances, surface treatment, inspection, etc. of flat-rolled stainless steel products (including plates, strips and sheets) in North America and even around the world. This article will focus on the most core part – the thickness tolerance of steel plates.
Why is the Thickness Tolerance of Stainless Steel Plates so Important?
A small thickness deviation may have a huge impact:
Project Cost: Steel is priced by weight. If the actual thickness of the steel plate generally exceeds the upper tolerance limit, it means that you are paying for “extra” materials, increasing the project cost.
Structural Safety: In load-bearing structures such as bridges and pressure vessels, designers rely on the minimum thickness when calculating strength. If the thickness of the steel plate is lower than the lower tolerance limit, it will directly threaten the safety and service life of the structure.
Processing and Assembly: During welding and assembly, consistent plate thickness is a prerequisite for ensuring assembly accuracy and welding quality. Plates with uneven thickness will cause misalignment, add additional grinding and filling work, and affect production efficiency.
Weight Estimation: Accurate thickness is the basis for accurately calculating transportation weight and lifting requirements.
How to Understand the Stainless Steel Plate Thickness Tolerances Table in ASTM A480?
The thickness tolerance in the ASTM A480 standard is not a single fixed value. It mainly depends on two key factors: the width of the steel plate and the nominal thickness of the steel plate.
The basic rule is:
The larger the width, the larger the allowable tolerance range.
The thicker the nominal thickness, the larger the allowable tolerance value (absolute value).
Example:
Let’s look at a practical example to better understand.
Suppose you ordered a batch of 304 stainless steel plates with a nominal thickness of 1/2 inch (12.70 mm) and a width of 60 inches (1524 mm) from us.
According to the tolerance table (Table A2.12) in the ASTM A480 standard, the allowable deviation of its thickness is usually -0.010 inches / +0.054 inches. (Note: This is an example value, please refer to the latest standard for details)
This means:
The minimum allowable thickness at any point on the steel plate is: 12.70 mm – (0.010 * 25.4) = 12.45 mm
The maximum allowable thickness at any point on the steel plate is: 12.70 mm + (0.054 * 25.4) = 14.07 mm
Therefore, as long as the thickness of the steel plate you receive is between 12.45mm and 14.07mm at any position, it fully complies with the ASTM A480 standard.
Disclaimer: The above data is for example only. In actual application, please always refer to the latest version of the official ASTM A480/A480M standard document for accurate tolerance values.
Practical Advice for Buyers
Clarify Purchasing Requirements: In your purchase order (PO), clearly indicate “All stainless steel plate dimensions and tolerances must comply with the latest ASTM A480 standard”. This is a clear and professional requirement.
Conduct Arrival Inspection: After receiving the goods, use a calibrated thickness gauge (micrometer) to perform sampling measurements at different locations of the steel plate (especially the edge and center).
Choose a Reliable Supplier: A trustworthy supplier can not only ensure that its products strictly comply with the standards, but also provide professional technical support and complete material test reports (MTC) when you have questions.
In Conclusion
Understanding the thickness tolerance of stainless steel plates is a key step to ensure the success of your project, control costs, and avoid risks. ASTM A480 provides you with a fair and transparent evaluation standard.
At Huaxiao Stainless Steel, we understand the value of standards. Every stainless steel plate we supply strictly follows the requirements of ASTM A480 and can provide complete documentation to ensure that you receive the product you see is what you get.
Have any questions about the steel plate tolerances required for your project? Or need a quote that guarantees compliance with standards?
Contact our technical experts today, and we will be happy to provide you with professional consultation and competitive quotes.