How to Control Subvendors and Outsourced Manufacturing in a Tower Internals Project

A tower internals supplier may manufacture some components internally while purchasing or subcontracting others.

Examples include:

• stainless-steel sheet;
• wire mesh;
• bolts;
• special machining;
• coating;
• external testing.

This is normal industrial supply practice.

The engineering issue is whether critical requirements remain controlled through the supply chain.

1. Identify Critical Purchased Items

Not every supplier needs the same level of control.

Critical examples may include:

• specified alloy sheet;
• wire mesh material;
• special fasteners;
• outsourced welding or machining.

2. Flow Down the Specification

A subvendor should receive the requirements relevant to its scope.

If the project requires SS316L, purchasing cannot simply state:

stainless steel.

3. Control Material Documentation

Where required, obtain:

• material certificate;
• batch identity;
• test information.

The main supplier remains responsible for connecting purchased material to the final product.

4. Qualification Should Match Risk

A supplier of standard cardboard cartons does not require the same technical qualification as a fabricator producing pressure-sensitive internal components.

5. Control Outsourced Processes

For external:

• machining;
• welding;
• testing;
• treatment;

define:

• drawing;
• procedure;
• acceptance criteria.

6. Incoming Inspection Still Matters

Receiving a certificate does not eliminate the need to check:

• quantity;
• identity;
• visible condition;
• dimensions where relevant.

7. Do Not Change Critical Subvendors Silently

If a project specifically approved a material source or subcontractor, a change may require customer notification or approval.

The contract governs.

8. Maintain Final Traceability

The end customer normally buys from the main supplier.

Therefore the main supplier should maintain the chain between:

Subvendor Material→ Manufacturing→ Inspection→ Final Product.

Engineering Takeaway

Subcontracting does not remove supplier responsibility.

Critical requirements should flow through:

Specification→ Subvendor PO→ Incoming Verification→ Production→ Final Documentation

The main supplier remains responsible for the finished package.