When importing from China, four main types of inspection are used: a factory audit, an inspection before production starts, control during production, and a final check before shipment (often plus container loading supervision). Each one closes its own stage and its own risk. The core principle is simple: you can influence quality only while the goods are still in China. Once the container leaves the port, returning or reworking the batch is practically impossible — so control is built before shipment, not after.
Below: what each inspection checks, at what stage to order it, how sampling under the ISO 2859-1 standard works, and which combination of inspections to choose for your situation — from a first order with a new supplier to recurring container batches.
Why quality control is risk management, not a formality
For a wholesale importer ordering by the container, the cost of a mistake is measured not by returning a single unit, but by frozen capital and missed delivery deadlines. Three fears stand behind every inspection decision:
- Financial loss from defects. A defective batch the size of a container can't be returned halfway around the world — the money is already transferred, the goods are already made.
- Quality substitution, "sample versus batch." The classic scheme (quality fade): the sample is flawless, but the production batch is quietly "cheapened" — a different material, thinner metal, simplified assembly. Without interim control, this is discovered only at the warehouse in Ukraine.
- Factory or trader. A middleman posing as a manufacturer doesn't control the line — and therefore isn't responsible for quality stability from batch to batch.
Inspections break these scenarios: they replace the promise "yes, everything's ready" with a documented fact. This is the difference between a full cycle (sourcing → verification → production → quality control → logistics) and a "logistics only" approach, where the cargo is accepted already packed, blindly. Before talking about types of inspections, it's worth making sure you're actually working with a manufacturer and not a reseller — this is covered in detail in the article "how to tell a manufacturer from a trader."
The four types of inspection and at what stage to order them
Inspections are tied not to the calendar, but to the batch's stage of readiness. Let's go through them in the order of the production cycle.
1. Factory Audit
When: before the first order, at the supplier selection stage. The audit evaluates the factory itself, not a specific batch: the presence and profile of production lines, capacity, the quality control system, certificates, the reality of the legal entity. This is the foundation — it answers the question "is this factory even capable of fulfilling my order consistently." It's worth consolidating the basic check of the legal entity and licenses into a single document before the visit — our "supplier verification checklist before prepayment" provides a reference, and step-by-step sourcing and verification of a factory is described in the article "how to find and verify a manufacturing factory in China."
2. Pre-Production Inspection (PPI)
When: after paying the deposit, but before mass production launches. This checks raw materials, components, and incoming materials — what your batch will be made from. This is the cheapest point to stop "cheapening": if the metal is the wrong grade or a component isn't the one in the approved sample, fixing it at the start costs pennies compared with reworking a finished container. Critical for technically complex goods and for cases where the material determines everything (metal, cable, battery cells).
3. During Production Inspection (DUPRO)
When: at roughly 20–50% batch readiness. The inspector checks the first assembled units on the actual line and detects systemic errors while only part of the volume has been made. This is the most effective way to avoid receiving a full container of identical defects: the error is caught on hundreds of units, not on tens of thousands. Especially recommended for new factories, complex products, and large batches.
4. Pre-Shipment Inspection (PSI)
When: at 80–100% batch readiness, when the goods are already packed. This is the most common type of control. The inspector takes a random sample according to a statistical plan (AQL — see below) and checks conformity to the specification, appearance, functionality, marking, and packaging. Based on the results, the batch is accepted, sent for rework, or rejected — while it's still at the supplier's warehouse, not at yours. For China-based supply, this is the very point where the foreign buyer finally sees a fact, not a promise.
5. Loading Supervision
When: on loading day. It confirms that exactly the right goods are going into the container, in the declared quantity, properly arranged and secured, with no substitution at the final step. Inexpensive, but it closes a separate risk: mis-sorting and short-loading, which otherwise are discovered only when unpacking in Ukraine.
Summarized by stage:
- Factory Audit (before the order): factory capability, lines, quality system, legal entity — critical for a new supplier.
- Pre-Production (PPI, after the deposit): raw materials, materials, components against the sample — critical for complex / material-intensive goods.
- During Production (DUPRO, 20–50% readiness): first units on the line, systemic errors — critical for large batches and new factories.
- Pre-Shipment (PSI, 80–100% readiness): sampling by AQL — quality, functionality, marking, packaging — critical practically always.
- Container Loading (loading day): quantity, arrangement, securing, absence of substitution — critical for container batches.
How sampling works: AQL and the ISO 2859-1 standard
Checking every single unit from a container of 30,000 pieces is unrealistic. That's why inspection relies on statistical sampling under the international standard ISO 2859-1 (the current edition is ISO 2859-1:2026, which as of 22.01.2026 replaced the 1999 version). The standard defines how many units to take from the batch and how many defects in the sample are permissible before rejecting the entire batch.
The key concept is AQL (Acceptable Quality Limit): the maximum defect proportion at which a batch is still accepted. Defects are classified into three types, and each is assigned its own level:
- Critical: danger to the user or violation of regulations. Standard AQL — 0: no critical defects in the sample.
- Major: affect the goods' fitness for sale. Typical AQL — 2.5.
- Minor: cosmetic deviations that don't hinder use. Typical AQL — 4.0.
The mechanics: based on the batch volume and the inspection level (by default — General Level II), the standard's tables give a code letter, then the sample size and the acceptance/rejection numbers. For example, for a batch of 5,000 units at Level II the sample size is about 200 pieces, and for each defect class the standard gives its own limit number. Exceed the limit on major defects and the batch is not accepted, even if "by eye" everything looks fine.
The practical consequence for the customer: the defect classification (what is critical, major, and minor for you) is set by you, not by the inspector. Without your clear list, the inspector decides subjectively — and results become a lottery.
What an inspection brief should contain
An inspection costs exactly as much as a good brief is worth. The more precisely it describes what to check and against which references, the lower the chance of a repeat visit and double costs. The minimum set:
- "Golden sample" — an approved reference against which the inspector compares the batch (not a "product idea").
- Defect classification into critical / major / minor with AQL levels for each.
- Specifications, drawings, BOM, tolerance tables, and marking and packaging mockups.
- Photos of reference and unacceptable units — to eliminate differing interpretations.
- Authority for the inspector to halt shipment on critical non-conformities — otherwise the decision is unenforceable.
- Report format — a detailed report with photo and video materials, understandable to you remotely.
- Responsible persons and communication channels on the side of the buyer, supplier, and inspection, so that approvals don't stall the check.
When to order each type of inspection
Not every batch needs the full control cycle. Be guided by risk — the level of trust in the supplier, the complexity of the goods, and the volume:
- First order with a new supplier: factory audit + final inspection (PSI) at a minimum. You don't yet know what the line is capable of.
- Large container batch: DUPRO + PSI + loading supervision. A systemic error must be caught before it's multiplied across the entire volume.
- Technically complex goods (electronics, industrial equipment, BESS components / solar modules): the full cycle, with emphasis on material inspection before production starts.
- Repeat order from a verified factory: a risk-oriented approach — often PSI is enough; with a stable history, the ISO 2859-1 standard even allows reduced control.
- Doubts about quality stability: return to tightened control — the standard expressly provides for switching to a stricter regime after rejections.
Quality control within the Silk Way Sourcing full cycle
The advantage of a China-based partner is that the inspector is physically next to the factory, not 7,000 km away. Silk Way Sourcing builds quality control into the entire chain — from factory verification to inspection of the finished batch before the final payment, with a real visit to production and a photo/video report. This is fundamentally different from the "logistics only" scheme, where cargo is accepted already packed and beyond control.
Hand the batch over for pre-shipment inspection — lock in the quality while the goods are still in China and something can still be changed. Write to us: contact@silkwaysourcing.com or WhatsApp +380 97 883 4765 — with a description of the goods and batch volume, and we'll propose a set of inspections matched to your risk.
