Four rungs, mirroring
ISO 18436-2.
TCAT's category structure maps one for one onto the categories ISO 18436-2 defines for vibration analysts. TCAT is a TIERA-issued credential aligned with the ISO 18436-2 body of knowledge. It is not an accredited ISO certification, TIERA is not an ISO certification body, and TCAT training hours do not count towards the formal training an accredited ISO 18436 certification requires.
What actually changes between Category I, II, III and IV.
Not the names — the job. Below is one ordinary machine: a motor driving a pump. Watch what each rung is expected to do with it. Nothing here needs any prior vibration knowledge.
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Swipe the panel sideways to see all of it — or read the same four statements as text further down.
Running. A trace of unbalance, as every real machine has.
Movement is exaggerated so it is visible at all. The fault shown is an
example so the machine is doing something — a category is defined by the
job you can do, not by one fault.
One machine. Four different jobs.
This is a motor driving a pump — the most ordinary machine in any plant. The four numbered squares are measurement points, one at each bearing. Every TCAT category is about this same machine. What changes between the rungs is what you are expected to DO with it.
Take the reading. Flag it if it is over the limit.
You walk a set route and measure each point with settings someone else configured. Your job is to notice that something has changed and to take a reading good enough to be trusted — not to say what is wrong.
Handheld · overall level · in or outName what is wrong, and say what to do about it.
You split the reading into frequencies and read the pattern: unbalance, misalignment, looseness, a bearing breaking up. You set the measurement up yourself, make the call, and recommend the correction.
Analyser · spectrum + waveformProve why it is happening — then correct it.
Two points measured together, the phase between them, and the machine measured while it runs up rather than at one steady speed. That is how a force is separated from a structure amplifying it. Corrections such as balancing sit at this rung.
Two-channel · phase + transientChange the machine, or change the programme.
The question stops being "what is wrong with this machine" and becomes "why does this keep happening, and what has to change so it stops": modelling, root cause, specifying and proving a fix, and running the programme other analysts work inside.
Modelling · root cause · programmeEvery rung above assumes the one below it as knowledge — but not as a certificate. Categories I and II are entered on verified experience alone. Only Categories III and IV additionally require the category below.
Which category you can enter depends on your experience — not on where you started.
TCAT is a mature-entry scheme. Verified experience alone gates Categories I and II, so an experienced analyst is not made to sit Category I first. Categories III and IV additionally require the category below.
Category I
Category I is the first rung of the TCAT credential. Entry is on verified work experience alone — no prior TCAT category is required.
EntryVerified experience only. No prior TCAT category required.
Category II
Category II is the rung TIERA is building first. Like Category I, entry is on verified work experience alone: an experienced analyst is not made to sit Category I first.
EntryVerified experience only. No prior TCAT category required.
Category III
Category III sits above Category II. Entry needs verified work experience and a held TCAT Category II — this is the point on the ladder where the category below stops being optional.
EntryVerified experience AND a held TCAT Category II.
Category IV
Category IV is the top of the TCAT ladder. Entry needs verified work experience and a held TCAT Category III.
EntryVerified experience AND a held TCAT Category III.
What does not change between rungs.
Experience is verified
Every category needs an employer or supervisor confirmation of field experience, checked by a person at TIERA before exam entitlement unlocks. How entry works.
Two assessed components
Knowledge items and graded diagnostic tasks, each passed on its own cut score. How assessment works.
Issued by TIERA
Aligned with the ISO 18436-2 body of knowledge, issued by TIERA, not by an accreditation body. Where this sits.
TCAT is a TIERA-issued credential aligned with the ISO 18436-2 body of knowledge. It is not an accredited ISO certification, TIERA is not an ISO certification body, and TCAT training hours do not count towards the formal training an accredited ISO 18436 certification requires.
No topic lists here yet.
The topic-by-topic syllabus for Categories I to IV is being authored. Until it is finished, no category page lists topics: a topic list on a paid credential page is a promise about what will be taught and examined, and we are not making that promise from a draft.
What is already decided — the entry route, the gating between categories and the two-component assessment — is published in full on the pages above.
Want the syllabus when it is published?
Tell us which category you are aiming at and we will let you know when its syllabus and enrolment open.