Visual Inspection of weld Joint

Visual Inspection of Weld Joints

Visual examinations of the weld joint of the weld metal is an important activity in welding for the welding Inspector, carried out to check the integrity and soundness of the weldment. Visual examinations is an economic activity. These activities, there doesn’t require any costly equipment. It should be carried out by a well-experienced inspector. The main responsibilities in Visual examinations of a welding inspector are:

👉 Code compliance.

👉 Workmanship control.

👉 Documentation Control.

The main requirements of the visual examination are:

1. The light intensity for the visual actually is measured in lux or foot-candles,  which is a measure of the way the eye responds to light-weighted to the response of the cone cells. So lux should be at least 350 Lux (minimum), but it is recommended to the carrying out a visual inspection at an illumination of more than 500 Lux.

2. The welding visual inspector's eye should be within the radii of 600 mm of the surface of the item being inspected and the viewing angle must not be less than 30 degrees.

Hi-low, Bridge cam gauge

(Also read)

Thickness range for the welder qualification test (WQT).

Thickness range for the base metal welding procedure specification (WPS)

Besides this above, Other aids that may be required during the visual examinations are:

👉 Welding gauges.

👉 Weld gap gauges.

👉 Linear misalignment gauges (Hi-Low).

👉 Magnifying glass (X2 to X5).

👉 Mirrored boroscope or fiber-optic viewing system (when access is restricted).

Stages of the Visual Inspection.

The Visual inspections may be done at three stages;

👉 Before welding

👉 During welding

👉 After welding

Before Welding:

👉 Before starting the Production welding, The inspector shall be familiarized with the applicable codes and standards/drawings/welding procedures specifications and procedure qualifications record (WPS and PQR).

👉 Welder qualification test (WQT) shall be carried out before the production welding. The inspector shall confirm the material and review the steel pipe MTC means Mill test certificates or mill test report (MTR) and certified material test report, materials inspection certificate.

👉 Welding consumables shall also be inspected before the welding.

👉 Joint preparation like cleaning of welding joining surface area, it should be free from dust and other impurities and alignment shall also be checked prior to welding. These all should be done according to the codes and standard which is given in WPS, PQR, and WQT,

👉 After confirmation of all the parameters (as mentioned above), the welding inspector can permit the welder to start the production welding.

👉 If the preheat is applicable according to the Welding procedure specification (WPS) and Procedure qualification report (PQR), then the preheat temperature shall be confirmed before starting the welding.

(Figure shows improper groove face and root gap, a welding inspector must see the groove preparation and root gap before welding)

During Welding:

👉 The inspector shall check the welding process and welding parameters with respect to the welding procedure specification (WPS) at any time during the welding of the production welding.

👉 During the Welding Root run and root run dressing, inter pass temperature shall be witnessed by the inspector.

👉 The welding consumables shall also be checked during the welding.

After welding:

👉 After successful completion of the welding, the identification number is punched near the joint.

👉 Complete visual inspection is done and any surface breaking or defect shall be repaired as per the approved procedure.

There are the following defects (or discontinuity) that can be revealed by visual inspection:

👉 Crack.

👉 Underfill.

👉 Undercut.

👉 Surface porosity.

👉 Overlap.

👉 Lack of sidewall fusion.

👉 Arc strike.

👉 Spatters.

👉 Excessive Penetration.

👉 Unacceptable weld profiles.

[Also read]

Mechanical or destructive test (DT) required for the welding procedure specification (WPS).

Mechanical or destructive test (DT) required for the Welder qualification test (WQT)

Welding inspector checking the weld reinforcement size by a Bridge Cam Welding Gauge

A dimensional survey shall be done to ensure the dimensions of the part after welding. After satisfactory completion of the welding proper documentation is prepared.

If a Post weld heat treatment (PWHT) is specified in welding procedure specification (WPS), Then the operation should be monitored and documented. Following parameters to be considered when Post weld heat treatment is required,

👉 Area to be heated.

👉 Heating and cooling rates.

👉 Holding temperature and duration.

👉 Temperature distribution.

In addition to the visual inspection, a number of other examination NDT (Non-Destructive Test) methods are available to check the quality of weldment of the weld joint.

👉 Before the welding, non-destructive testing may be used for the check surface of the weld area.

👉 During the welding root and other passes may be checked.

👉 After, during, and before the welding some of the most common Non-destructive testing (NDT) methods are;

👉 Radiography testing (RT)

👉 Ultrasonic testing (UT)

👉 Magnetic particle testing (MPT)

👉 Liquid penetrant testing (LPT)

👉 Electromagnetic testing (ET)

👉 Acoustic emission testing (AET)

Each Non-destructive testing (NDT) method has its own significance and importance for example Liquid penetrant testing is very efficient and economical for checking surface defects, whereas, with the help of an Ultrasonic test and Radiography test, the entire depth of the weld can be inspected.

The selection of Each Non-destructive testing (NDT) method depends on the requirements. A person engaged or assigned to carry out these tests must possess the necessary qualification. A written test procedure, format for reporting, and the application code must also be decided before conducting the examination.

Also, read

Qualification stages of Welding procedure specification (WPS).

LIfe of 3 layer polyethylene (3LPE) coating.

Dirax (HDD) sleeve and their features