Q355 vs S355: Audit Suffix, Impact and Delivery State
The matching strength number in two grade names does not approve a material change. Start with the complete suffix and project requirement on each side, then identify the ordered product form and thickness. Ask the design owner which impact, fabrication and test conditions control the part before seeking a revised offer.
Scope of this comparison
A shared strength number is not a substitute for quality suffix, impact requirement, form, delivery state and design approval.
Quality
Write the complete suffix
Condition
Match form, size and delivery
Tests
Specify the required evidence
Approval
Obtain a written design decision
Confirm Both Complete Grade Suffixes
Copy the full Q355 and S355 designations from the drawing, offer and proposed mill documents. Include each governing product standard and edition. If either side names only the grade family, ask for the missing quality or suffix before comparing it with another product.
Name the finished component and the material actually ordered. A steel coil to be cut and fabricated, a plate and a structural section are different purchase descriptions. Record the intended form and processing route so a material review compares the items that will really be delivered.
Check Standard Scope and Impact Requirements
Obtain the applicable current clauses for the exact qualities in both standards. Ask the design owner whether the project requires an impact test, at what temperature, with what specimen and acceptance method. Do not infer the requirement from a similar-looking grade number or omit it because a generic comparison table does not display it.
Record which standard clause applies to the actual ordered form. A public catalogue record identifies a document, but it cannot settle the grade-specific impact class or approve a different material for the project.
Match Product Form, Thickness and Delivery
Put the requested form, thickness or section size, delivery condition and any processing steps next to each full grade identity. Ask whether the relevant clauses and inspection requirements differ at that size or condition. If one quote is for coil and the other for a finished section, resolve the purchased-input and finished-part specifications separately.
Have the supplier state exceptions in writing. The material engineer should review those exceptions against the drawing, fabrication method and code before the procurement team treats the offers as comparable.
Have a Specification Ready?
Send what you already know, such as grade, finish, size or quantity. Inquiries are answered within 2 hours.
Compare the Project's Required Properties
Build a requirement sheet from the drawing and order: chemistry, mechanical test, impact result if required, tolerances, inspection and any supplementary conditions. For each item, place the applicable clause and the proposed MTC field side by side. Leave a gap where the current text or test basis has not been supplied.
Ask the designer and fabrication owner whether forming, welding, connections or service conditions change the acceptance decision. A nominal strength similarity is one input to investigate, not proof that all ordered properties and procedures align.
Record Approval and Delivery Evidence
Send the complete material identities, standard editions, form, thickness, delivery state, quantity and required tests with the inquiry. State whether the offered item differs from the project drawing. Have the authorized design owner approve any change in writing and update the purchase order and inspection requirements accordingly.
At receipt, match the approved order, package or coil identifier, heat or lot and MTC. Record unresolved differences before processing. Ask ZIVO STEEL to confirm only the exact material, form and documentation it can actually offer; a quotation cannot replace engineering approval.
Side-By-Side Comparison
| Attribute | Complete Q355 quality | Complete S355 quality | Basis |
|---|---|---|---|
| Full grade and edition | Obtain the complete Q355 suffix and applicable product-standard edition. | Obtain the complete S355 suffix and applicable product-standard edition. | Drawing, quotation and current standard texts for exact qualities. |
| Impact and test basis | Check whether this quality and size meet the project impact-test requirement. | Check the same temperature, specimen and acceptance requirement for the proposed quality. | Design specification and the actual clauses and reported test results. |
| Form and delivery | Record ordered form, thickness, condition and subsequent fabrication. | Record the proposed form, thickness, condition and fabrication. | Product-form clauses and project drawing; avoid name-only matching. |
| Decision and evidence | Match the approved Q355 offer and heat documents to the order. | Obtain design change approval before treating S355 as an alternative, then match its documents. | Authorized design decision, purchase order and mill test certificate. |
Frequently Asked Questions
No. Identify the full qualities, editions, product forms, thicknesses, delivery states and project tests before asking the design owner to review a proposed change.
Check the drawing and applicable standard clauses for the exact quality and ordered form. Record the required test temperature, specimen basis and acceptance method if the project invokes an impact test.
Attach both full order identities, a clause-by-clause comparison, the relevant MTC and fabrication evidence, plus written approval from the authorized project design owner.
Tell Us What You Need
Send the product form, grade, finish, thickness, width, length and quantity. Inquiries are answered within 2 hours.
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