Need of Welding Process Validation and Welder Skill Tests

By
Amol Bhalerao
-
0
283

Satish Keskar, DME, DBM, MMS,
IIW-IWT, AWS-CWI, ISO 3834, Lead Auditor
As we know that welding processes are widely used in variety of industrial sectors such as Boiler & Pressure Vessels, Steel Structure & Metal Buildings, Machine Building, Automotive Sector, Bridge Fabrication etc. The major Welding Processes involved are;

  • SMAW – Shielded Metal Arc Welding
  • GMAW – Gas Metal Arc Welding
  • FCAW – Flux Core Arc Welding
  • GTAW – Gas Tungsten Arc Welding
  • SAW         – Submerged Arc Welding
  • RW – Resistance Welding

Welding processes are having with variables like current, voltage, travel speed, position, welding electrode, material to be welded etc. The quality of welding has great effect of these variables, therefore it is essential to have proper control on these variables in the beginning to avoid rework / rejection.
Secondly, special processes (e.g. welding / painting) needs to be validated because the resulting output cannot be verified by subsequent monitoring and measurement and as a consequence, the deficiencies become apparent only after the product is in use or the service has been delivered. Ref. : ISO 9001 : 2015 clause 8.5.1
Steps of Welding Process Validation:-

  • To prepare Preliminary Welding Procedure Specification (pWPS) in which all variables are listed and provide guidelines on how to weld
  • To prepare Test Piece and get it welded from a welder in accordance Preliminary Welding Procedure Specification (pWPS)
  • To carry out Non-destructive (NDT) and/or Destructive (DT) Tests by referring related code / standard / specification
  • Review results of Non-destructive (NDT) and/or Destructive (DT) Tests referring related code / standard / specification
  • When results of Non-destructive (NDT) and/or Destructive (DT) Tests are found satisfactory, the welding process is deemed as validated
  • Prepare and maintain the documentation involved in Validation i.e. WPS & PQR

Tests involved in Welding Process Validation:-
Non-destructive (NDT) Test —–>

  • Visual Test (VT) —- Visual appreance and size of welds to be determined
  • Ultrasonic Test (UT) —- Soundness of the welding to be determined
  • or Radiography Test (RT) —- Soundness of the welding to be determined

Destructive (DT) Tests ——>

  • Tensile Test —- To verify the yield and ultimate tensile strength of welding is matching with the parent metals being welded
  • Guided Bend Test —- To verify that welding is having required ductility from Which the soundness of welding is being ascertained

Steps of Welding Skill Test / Welder Performance Qualification (WPQ):-

  • To refer validated Welding Procedure Specification (WPS) in which all variables are listed and which provide guidelines on how to weld
  • To prepare Test Piece and get it welded from the welder in accordance validated Welding Procedure Specification (WPS)
  • To carry out Non-destructive (NDT) or Destructive (DT) Tests by referring related code / standard / specification
  • Review results of Non-destructive (NDT) or Destructive (DT) Tests referring related code / standard / specification
  • When results of Non-destructive (NDT) or Destructive (DT) Tests are found satisfactory, the welder is deemed as having required skill and certified.
  • Prepare and maintain the documentation involved in Welder Skill Test i.e. WPQ

Tests involved in Welder Skill Test:-
Non-destructive (NDT) Test —–>
Visual Test (VT)                                 —- Visual appreance and size of welds to be determined
Ultrasonic Test (UT)                         —- Soundness of the welding to be determined  OR
Radiography Test (RT)                    —- Soundness of the welding to be determined
OR
Destructive (DT) Tests ——>
Guided Bend Test              —- To verify that welding is having required ductility from
Which the soundness of welding is being ascertained
Typical Reference Codes/Standards for Welding Process Validation & Welder Skill Test
Boiler & Pressure Vessel Industry            –  Indian Boiler Regulations / ASME Section IX
Steel Structure and Metal Building          –  AWS D 1.1
Sheet metal fabrication                               –  AWS D 1.3
Automotive Industry                                   –  AWS D 8.1, AWS D 8.6 to AWS D 8.9 as applicable.
Bridge Welding Code                                  –  AWS D 1.5
Summary:-

  • The training to welders (awareness & theoretical inputs) should be treated as an investment and not expenses.
  • The documentation of welding processes validation are documentary evidences and can be produced to Clients / Certification body.
  • Welder skill tests is similar to driving license provided to welders for welding certain jobs.