Regulatory glossary

IQ OQ PQ: Equipment and Process Qualification, Explained

IQ, OQ and PQ are the three qualification stages a piece of equipment or a system goes through before it can be used to make product. In one line each:

• IQ, Installation Qualification. It was installed the way the specification says.
• OQ, Operational Qualification. It works across its intended operating range.
• PQ, Performance Qualification. It works on your product, in your process, repeatedly.

The progression is deliberate. Each stage assumes the previous one passed, which is why running them out of order or in parallel to save time tends to produce findings rather than a shorter timeline.

What each stage actually covers

Installation Qualification

Documented verification that the equipment as delivered and installed matches what was specified and what the manufacturer supplies.

Typically: equipment identification and serial numbers, location, utilities and services connected as required, materials of construction of product-contact parts, software and firmware versions, calibration status of instruments, and that the manuals, drawings and spare parts list are present.

IQ is where discrepancies between the purchase specification and what actually arrived get caught. It is also the least interesting stage and the one most often rushed, which is why so many OQ deviations trace back to something an IQ should have found.

Operational Qualification

Documented verification that the equipment operates as intended across its whole intended range, not just at the setpoint you plan to use.

Typically: functional testing of each operating parameter, challenge at the upper and lower limits of the range, alarms and interlocks, failure and recovery behaviour, power loss and restart, security and access controls, and any automated sequences.

The characteristic mistake is testing only at nominal conditions. An OQ that proves an oven holds 60 °C when the range is 40–80 °C has qualified one point, not a range, and the process cannot then legitimately move within that range.

Performance Qualification

Documented verification that the equipment performs consistently using the actual product and process, under conditions representing routine production.

Typically: runs at production scale with real materials, replicate batches or cycles to demonstrate reproducibility, worst-case conditions where the process allows, and acceptance criteria drawn from the product's own specifications.

PQ is the first stage where the product's requirements, rather than the equipment's, set the acceptance criteria.

Where DQ fits

You will often see DQ, Design Qualification, in front of IQ: documented verification that the proposed design is suitable for its intended purpose, carried out before anything is purchased.

DQ is standard practice for computerised systems and custom equipment and is part of GAMP 5's approach. It is not universal for off-the-shelf equipment, where the user requirements specification and vendor assessment often serve the same purpose.

How this maps to FDA's process validation lifecycle

This is the connection people miss. FDA's process validation guidance describes a three-stage lifecycle, and IQ/OQ/PQ sits inside it rather than alongside it:

Two consequences worth stating. Equipment PQ is not the same as Process Performance Qualification (PPQ). Equipment PQ shows the machine performs on your product. PPQ shows the whole commercial process reproducibly makes conforming product. And qualification is not a one-time event: Stage 3 expects continued verification, and a change to the equipment or process sends you back for requalification under change control.

Common findings

• Protocol approved after execution. Protocols are approved before running, results afterwards. Signature dates that say otherwise are a data integrity observation, not a paperwork slip.
• Acceptance criteria written to match the result. Criteria come from the requirement, not from what the equipment happened to do.
• Deviations closed without impact assessment. Every qualification deviation needs a documented assessment of its effect on the qualified state.
• OQ at setpoint only, as above.
• No requalification trigger. Change control has to name what kind of change sends equipment back through which stage.
• Vendor documentation adopted wholesale. A vendor FAT or SAT package is useful input, not your qualification. The obligation is yours.