Mill, stockholder, distributor and service centre: who does what?

Steel suppliers are often described with overlapping terms: mill, stockholder, distributor, service centre, trader, agent.

The names are not perfectly standardized, and one company can perform several roles at once.

For procurement, the useful question is not what the company calls itself. It is:

What does it physically control—production, stock, processing, certification or only the commercial transaction?

Steel mill / manufacturer

A mill manufactures the steel product.

Depending on its capabilities, it may control:

• steelmaking;
• casting;
• rolling;
• tube forming/welding;
• heat treatment;
• testing;
• final marking;
• original inspection certification.

Examples include plate mills, section mills, seamless tube mills, HFI mills and SAW pipe mills.

Mill strengths

• custom production;
• defined manufacturing route;
• project-specific testing/options;
• direct original MTC;
• larger size/grade programs;
• technical production records.

Mill limitations

• MOQ;
• rolling campaigns;
• longer lead time;
• fixed production ranges;
• less flexibility for small mixed quantities.

For uncommon material, "mill can make it" does not mean "mill will make 3 tonnes next week".

Stockholder

A stockholder buys material in advance and holds physical inventory for resale.

Its main value is availability.

A stockholder can often supply:

• small quantities;
• mixed sizes;
• short lead times;
• material from several mills;
• cut lengths/plates.

The stockholder should maintain traceability to the manufacturer's documentation.

Under EN 10204, an intermediary transmits the manufacturer's inspection document/copy while preserving identification/traceability; it does not turn itself into the original manufacturer simply by reselling the material.

Distributor

Distributor is a broad commercial term.

A distributor may:

• hold stock itself;
• sell a manufacturer's products in a territory;
• buy and resell on order;
• combine mill and stock sources;
• manage logistics/documentation.

Therefore the label alone does not prove that material is physically in stock.

When stock availability matters, ask for:

• current inventory;
• heat/MTC availability;
• warehouse location;
• reserved quantity;
• physical inspection/photos if necessary.

Service centre

A service centre adds processing to stockholding/distribution.

Typical services include:

• cutting to length;
• plate cutting;
• sawing;
• slitting;
• decoiling;
• shot blasting;
• priming;
• machining;
• beveling;
• drilling;
• marking;
• packing.

A service centre can turn standard stock into a customer-specific delivery package without manufacturing the original steel.

This makes traceability after processing especially important.

See Traceability when stockholders cut material from master lengths or plates.

Trader

A trader mainly manages the commercial transaction and sourcing network.

It may not own:

• a mill;
• a warehouse;
• processing equipment.

A good trader can still add value through:

• market access;
• mill relationships;
• credit/payment structure;
• export logistics;
• documentation coordination;
• sourcing unusual products.

But if the project requires in-house stock or processing, verify that capability rather than assuming it.

Agent / representative

An agent or sales representative usually acts for a mill or supplier rather than purchasing/reselling the material in its own name.

The commercial contract may still be directly between buyer and manufacturer.

This distinction matters for:

• who issues the invoice;
• who carries credit risk;
• who gives warranty;
• who issues/holds documentation;
• who is contractually responsible for delivery.

Which supplier can change the material?

This is an important practical distinction.

Mill

Can potentially change production parameters within the governing specification before manufacture, e.g.:

• grade;
• chemistry controls;
• delivery condition;
• testing;
• dimensions;
• marking.

But only within its qualified capability and subject to MOQ/lead time.

Stockholder/service centre

Can often change the physical delivery form:

• cut length;
• cut plate dimensions;
• bevel/machine;
• blast/prime;
• re-pack.

It generally cannot retroactively change how the original steel was made.

Additional testing may demonstrate additional properties, but it does not automatically rewrite the original mill manufacturing history or certificate.

Who issues the MTC?

The original manufacturer's EN 10204 inspection certificate comes from the manufacturer under the applicable certification route.

An intermediary can transmit the original or a controlled copy and maintain piece-to-document traceability.

A stockholder's declaration or cutting certificate can supplement this chain but should not be confused with a newly created mill inspection certificate.

Which supplier type should you approach?

Choose a mill when:

• quantity is large enough;
• grade/size is special;
• supplementary tests are needed at production;
• project-specific manufacturing is required;
• lead time allows a mill order.

Choose a stockholder when:

• quantity is small;
• delivery is urgent;
• standard stock sizes are acceptable;
• mixed products/mills are acceptable.

Choose a service centre when:

• you need stock plus cutting/processing;
• project piece lengths differ from mill lengths;
• plate nesting/cutting adds value.

Use a distributor/trader when:

• several origins need to be combined;
• the commercial/logistics structure is complex;
• direct mill access is impractical.

In reality, the best supplier may combine several of these roles.

Questions to ask a supplier

Instead of asking only "Are you a stockholder?", ask:

• Is the material physically in your own warehouse?
• Can you provide the heat list/MTC now?
• Who is the original manufacturer?
• Will you invoice as seller or act as agent?
• What processing is done in-house?
• How is traceability maintained after cutting?
• Which tests can be added to stock material?
• What must be done by the original mill?
• If new production is needed, what MOQ and rolling window apply?

These questions reveal the actual supply route.

Procurement takeaway

Supplier labels are useful, but capability matters more.

Mill = makes the steel.
Stockholder = holds steel.
Service centre = processes stock.
Distributor/trader = organizes the commercial supply route.

Many companies combine these functions, so verify what is actually being offered for the specific order.

References and verification sources

• DIN EN 10204:2005-01 — Metallic products, types of inspection documents
• Dillinger — Customer information concerning inspection documents according to EN 10204