Visual inspection
(VT)
Visual inspection is the most common and primary NDT method — the quickest and
the most cost-effective way to ensure surface quality, weld geometry and structural condition
prior to other inspection methods. Inspection in accordance with the EN ISO 17637 standard covers
all materials without radiation or special chemicals. AI-assisted
Our reporting system delivers an audit-ready report in even under 24 hours.
- Foundations of NDT: fast and cost-effective surface testing for all materials
METHOD
PRINCIPLE
Visual testing (VT) is based on the systematic visual assessment by a certified inspector. In direct VT, the inspector observes the object immediately — in indirect VT, mirrors, borescopes, endoscopes or
camera systems for hard-to-reach locations.
The method detects surface-breaking defects
such as cracks, pores, incomplete welds, undercut, geometric inaccuracies and
corrosion and wear damage.
VT always precedes other NDT methods — it is an essential preliminary phase, the findings of which
guide the targeting of follow-up inspections.
Note
VT is the only NDT method that standards always require before other methods. VT is suitable for all materials — steel, aluminium, titanium, polymers and composites — without limitations regarding magnetic properties or material type.
SUITABILITY
SUITABLE MATERIALS AND STRUCTURES
- Carbon steel, alloy steels and stainless steel (austenitic and ferritic)
- Aluminium, titanium and non-ferromagnecic alloys
- Castings, forgings and pressings
- Pipes, pressure equipment and tank structures
- Welded joints in all geometries
- Polymers, composites and ceramic structures
FASTEST REPORTING IN THE INDUSTRY
Our AI-assisted reporting system enables an audit-ready inspection record in even under 24 hours — including for urgent orders and large-scale projects.
FLEXIBLE IMPLEMENTATION
Inspections are carried out at night and at weekends where necessary — when the production schedule does not give way and quality cannot wait.
ALL MATERIALS, NO RADIATION
VT is suitable for all materials without radiation protection areas or special chemicals — the quickest way to ensure surface quality before further operations.
AUDIT PROCESS STEP BY STEP
The inspector familiarises themselves with the drawings, welding procedure specifications (WPS) and applicable standards.
The inspection surface is cleaned of spatter, grease, dirt and loose material. This ensures favourable conditions for detecting defects.
A certified Level II or Level III inspector will examine the item in accordance with EN ISO 17637. Hard-to-reach areas are inspected using mirrors, borescopes or camera systems.
The detected indications are evaluated against the acceptance criteria and documented with photographs as well as location and size markings. Unclear cases are directed to further inspection (e.g. MT or PT).
The inspection report contains the object description, parameters, photographic documentation, observed indications and the approval decision — ready to be attached to the QA/QC documentation.
TYPICAL APPLICATIONS
01
Visual inspection of weld seams prior to other NDT methods — mandatory
preliminary phase in standards-compliant quality assurance
02
Pre-inspections of piping and pipe spools prior to radiographic or ultrasonic testing
03
Pressure equipment and vessel structures (PED 2014/68/EU) — inspections during the receiving and manufacturing stages
04
Cranes, lifting appliances and load-bearing steel structures — periodic and
maintenance inspections
05
Welded joints and surface inspections of structures in the shipyard and shipbuilding industry
06
In-service inspections: corrosion, erosion and mechanical damage in operational equipment
VT alongside NDT methods
The following comparison helps to select the most suitable method or combination of methods for the situation:
| Feature | VT | MT | PT | dRT / UT |
|---|---|---|---|---|
| Painted (open) | ✓ Excellent | ✓ Excellent | ✓ Excellent | Limited |
| subsurface defects | ✗ Not suitable | ✓ Partly | ✗ Not suitable | ✓ Excellent |
| All materials | ✓ Yes | ✗ Cast iron | ✓ Non-porous | ✓ Metals |
| Freedom from radiation | ✓ Yes | ✓ Yes | ✓ Yes | ✗ dRT: radiation |
| No special chemicals | ✓ Yes | Liquids | ✗ Chemicals | ✓ Yes |
| Geometry assessment | ✓ Excellent | ✗ Not suitable | ✗ Not suitable | Partly |
| Compulsory preliminary stage | ✓ Always first | ✗ No | ✗ No | ✗ No |
| Speed / efficiency | ✓ Fast | ✓ Fast | ✓ Fast | ✓ Fast |
VT — Visual inspection
Magnetic particle testing
Turku University Neuropsychological Rehabilitation Test
dRT / UT — X-ray & Ultrasound
Note VT is the only NDT method that standards always require before other methods. The combination of VT and MT or PT covers surface defects comprehensively — findings from VT effectively guide the targeting of further inspection methods.
Customer benefits
Safety and compliance
The non-radiation method does not require any special protection zones. The reporting complies with the requirements of EN ISO 17637, SFS-EN ISO 9712 and project-specific requirements — audit-ready documentation for the authorities and the end customer.
Life cycle data
Photographic documentation enables long-term monitoring: the same subject can be compared with previous inspections to identify the progression of corrosion, wear or fatigue cracking — supporting predictive maintenance.
Cost-effectiveness
VT is the most cost-effective of the NDT methods — no specialised equipment, no chemicals, no radiation protection areas. Early defect detection prevents costly repair welds, production downtime and warranty claims.
Based on all NDT methods
The findings of the VT guide the targeting of follow-up examinations. An effective VT reduces the number of unnecessary dRT or UT examinations — overall costs are reduced when resources are allocated to the right areas at the right time.
Speed and Flexibility
No development process, no waiting time — inspection result immediately available. The AI-assisted reporting system delivers an audit-ready report in even less than 24 hours.
Flexibility on the pitch
VT inspection does not require heavy equipment: the inspection can be carried out directly at the installation site, next to the production line, or in tight structures. It can be carried out alongside production without any production downtime.
QUALIFICATION
STANDARDS AND CERTIFICATION
The inspectors at NDT Aura Oy operate in accordance with the standards listed below — This guarantees a technically competent and legally acceptable inspection result
NDT programme
VT and comprehensive NDT inspection
VT is an essential first step in every inspection campaign — its findings guide the targeting of other methods. NDT Aura Oy can consult on the formulation of the most suitable inspection programme based on the risk level of the asset and applicable standards:
NDT Aura Oy can consult on the formation of the most suitable inspection programme based on the risk level of the object and applicable standards.
FREQUENTLY ASKED QUESTIONS (FAQ)
Visual testing (VT) is the most common and primary NDT method, in which a certified inspector visually assesses the condition of the surface, weld geometry and structural discontinuities either with the naked eye or by using optical aids. VT detects open surface defects such as cracks, porosity, incomplete fusion, undercuts and geometric deviations. Standards require VT to be performed always before other NDT methods.
VT is always the first stage: it precedes all other NDT methods. In accordance with standards EN ISO 17637 and EN 13018, visual testing is mandatory prior to MT, PT, dRT or UT inspections. VT findings guide the targeting of further inspections — efficient VT reduces unnecessary and more expensive inspections.
Our AI-assisted reporting system enables an audit-ready inspection record in even under 24 hours from the completion of the inspection. In urgent situations, we can evaluate the schedule of even a broader entity together — often the same day or the following morning. This is one of our most significant competitive advantages in the industry.
Yes. Unlike magnetic particle testing (MT), which is only suitable for ferromagnetic materials, VT is suitable for all materials: steel, aluminium, titanium, stainless steel, copper, polymers, composites and ceramic materials. The material imposes no limitations — the method is universal.
Not necessarily. VT is radiation-free and does not require special shields, chemicals or heavy equipment. The inspection can often be carried out alongside production directly at the installation site. EN ISO 17637 requires a minimum illumination level of 500 lux, which is easy to arrange even in the field. Inspections are carried out at night or at weekends if necessary.
A rough description of the object is sufficient: material, welding process, surface area or number of welds to be inspected, applicable standard or project requirement, and desired schedule. Drawings and isometric views significantly speed up the preparation of the quote. We are also happy to be contacted by phone in urgent situations — we will dispatch an inspector with as short a notice as possible. You will also receive an order form from us, filling which ensures high-quality and fast reporting, and that invoicing is directed correctly.
Request for quotation
Request a quote for a visual inspection
(VT) — quick response, audit-ready documentation
Tell us about the inspection object, material, applicable standard and schedule — we will respond to your request for quote quickly. Send the drawings or a short project description, and we will help you choose the technically correct NDT method or combination of methods.
