Schweißnaht-Inspektionskamera: So prüfen Sie innere Schweißnähte mit einem Endoskop

External welds can often be examined directly with adequate access, lighting and the appropriate visual inspection procedure. Internal welds are more difficult. A weld root, internal bead or adjacent surface may sit inside a tube, housing, header or fabricated assembly where the inspector cannot obtain a direct line of sight.A weld inspection camera such as an industrial borescope or videoscope can extend visual access into these areas without cutting open the component. The camera can document surface-visible weld conditions, but useful evidence depends on more than resolution. Access geometry, viewing direction, working distance, illumination, probe stability and inspection records all affect the result.

The first question is therefore not “How many megapixels does the camera have?” It is “Can the probe reach the weld and place the camera at the correct angle and distance?”

What Can a Weld Inspection Camera Actually Show?

A borescope provides remote visual inspection of a surface that the camera and lighting can reach. It does not see through the material.

This distinction is important because some weld conditions can produce visible surface indications, while other discontinuities may exist below the visible surface and require another inspection method.

Laut der American Society for Nondestructive Testing (ASNT), borescopes and video scopes are used for remote visual testing when a surface cannot be viewed directly. For welded joints, ISO 17637:2016 specifies visual testing of fusion welds in metallic materials. The governing inspection procedure and acceptance criteria should always take priority over a generic camera guide.

Where Borescope Weld Inspection Works Well

Borescope weld inspection is most useful when the weld surface is physically reachable by a probe but cannot be examined conveniently with direct vision.

For broader production-line inspection, castings, machinery and factory quality-control applications beyond welds, see QBH’s manufacturing inspection applications.

Map the Weld Before Choosing the Camera

The inspection route determines which camera architecture will work.

Before comparing screens, image resolution or recording features, define four physical constraints:

• The smallest opening the complete camera head must pass through
• The route from the access point to the weld
• The position of the weld relative to the probe axis
• The expected camera-to-weld working distance

Measure the Complete Access Route

A stated probe diameter may not represent every part that must pass through the opening. Protective rings, articulation joints, sleeves, mirrors or adapters can increase the maximum outside diameter.

The route also matters after the camera enters. A probe that fits through the first opening may still encounter a bend, flange transition or internal restriction before reaching the weld.

Determine Where the Weld Sits Relative to the Camera

A weld directly ahead of the insertion path creates a different inspection problem from a weld running around the side wall of a pipe.

If the target remains beside the probe, a lateral viewing system may be effective. If the viewing direction changes continuously or the weld is partly hidden behind nearby geometry, active steering becomes more important.

Choose the Viewing System by Weld Geometry

No single probe architecture is correct for every internal weld.

When a Dual-Camera Probe Is Useful

A front-and-side configuration can work well when the inspection path is repeatable and the internal weld normally sits at a predictable lateral position. The forward lens helps locate the inspection zone; the side lens then provides a more direct view of the adjacent weld surface.

For available configurations, review the QBH front-and-side dual-camera borescope range.

For a deeper explanation of lateral working distance, glare and probe rotation, use the separate side-camera borescope inspection guide.

When Articulation Is More Appropriate

If the inspector must aim around an obstruction, approach the weld from several angles or hold a small weld area steadily in frame, a steerable probe is usually a better architecture than adding another fixed lens.

In these cases, compare suitable articulating borescope configurations.

Focus, Lighting and Image Quality on Weld Surfaces

Image quality during weld inspection is often limited by optics and lighting before it is limited by nominal resolution.

Die American Welding Society’s 2026 video borescope inspection guide for CWIs also notes that excessive illumination on reflective weld surfaces can cause blooming and wash out useful bead detail. This is why probe-light control and viewing angle should be evaluated on the actual metal surface rather than judged from an open-air demonstration.

Reflective Metal Can Produce Glare and Blooming

Stainless steel, polished metal and curved weld beads can reflect probe light directly back toward the camera sensor. If illumination is too strong, bright areas may lose detail even though the overall image appears well lit.

Begin with moderate probe illumination and adjust it while observing the actual weld. Maximum LED output should not be treated as the default setting.

Working Distance Matters as Much as Resolution

A weld can be visible but still sit outside the lens’s usable focus range.

This is especially important inside small-diameter tubes, where a side-facing lens may sit very close to the weld or pipe wall. More pixels and digital zoom cannot recover detail that was never optically focused.

During equipment evaluation, place the probe at approximately the same distance from a representative weld as it will operate in the real component.

Do Not Depend on One Image

When a possible indication is found, record more than one view where practical. A second image with slightly different lighting or viewing angle can help determine whether the feature remains visible or disappears with glare.

For important findings, capture both a context image showing the location and a closer image showing the surface detail.

Positioning and Accessories That Improve Repeatability

The camera itself is only part of an internal weld inspection system. Probe positioning can strongly affect image quality and repeatability.

These accessories should be evaluated against the complete camera-head clearance. Adding a centering device, side-view adapter or sleeve can increase the effective diameter of the inspection assembly.

Internal Weld Borescope Inspection Workflow

A defined sequence produces more useful evidence than moving the probe randomly until a defect-like feature appears.

1. Identify the Weld and Inspection Objective

Record which joint is being inspected and which surface must be visible. A root-side verification and a full circumferential visual scan may require different camera positions.

2. Map the Access Route

Identify the entry point, bends, restrictions and insertion distance before moving the camera toward the weld.

Do not force the probe through a restriction simply because the nominal diameter appears small enough.

3. Establish Orientation Before the Close-Up

Capture a recognizable reference or begin from a defined probe orientation. For a circumferential weld, a clock-position or quadrant system can make later image review much easier.

4. Set the Actual Working Distance

Move the camera to a distance where the weld remains sharp. Then adjust probe illumination to preserve contrast without washing out reflective metal.

5. Scan the Weld in Defined Sections

For a circumferential joint, inspect one defined sector at a time rather than rotating the probe without a reference.

For a long linear seam, a controlled pull-back can sometimes produce steadier video than repeatedly pushing the probe forward. Insert to the end of the planned inspection zone, establish the required viewing direction and then withdraw the probe slowly while recording, when the geometry and approved procedure allow it.

6. Capture Context and Detail

When a suspicious feature appears, record the surrounding weld area first. Then capture a closer view and, where practical, additional images with a slightly different angle or illumination level.

This makes later review more reliable and reduces the chance that a single reflection or imaging artifact will be treated as a persistent surface condition.

Record the Weld Position, Not Just the Image

A sharp internal image has limited value if nobody can determine where it came from.

A practical remote visual weld record should connect every relevant image or video to a defined location.

Measurement Requires the Right System

Standard borescopes are effective for visual documentation but should not automatically be treated as calibrated measurement instruments.

Some advanced videoscopes use dedicated measurement technologies to estimate or measure the size of visible indications. When dimensional acceptance depends on those measurements, verify the measurement method, calibration requirements, operating procedure and required accuracy before purchasing the system.

Know the Limits of Remote Visual Weld Inspection

A camera expands visual access. It does not replace every other form of weld examination.

Further evaluation may be required when:

• The suspected discontinuity is below the visible surface
• The acceptance requirement depends on dimensions the camera cannot measure reliably
• The governing procedure requires ultrasonic, radiographic, penetrant, magnetic or another NDT method
• The image cannot distinguish a surface condition from glare or contamination
• The required weld surface cannot be reached from a suitable viewing angle
• The decision is safety-critical and exceeds the capability of the available visual system

How B2B Buyers Should Validate a Weld-Inspection Sample

For distributors, industrial tool brands and professional inspection-equipment buyers, the most useful sample test is not an open-air demonstration. It is a repeatable inspection of a representative metal weld through a realistic access route.

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