This document covers the procedure to prepare a WPS – Welding Procedure Specification & PQR – Procedure Qualification Record for Overlay weld, Corrosion Resistant Overlay and Wear Resistant Overlay both.
The procedure refers international standard ASME BPVC Section IX, ( American Society of Mechanical Engineers, Boiler and Pressure Vessel Code )
This procedure of WPS and WQT is suitable for and welding process, SMAW / GMAW / GTAW or any .
Overlay is a process of Welding a metal over the surface of another base metal, mostly with filler metal of different chemical composition and mechanical properties .
The purpose of overlay is to create a layer of metal more suitable to the work environment, the property which the base metal may lag .
Depending on the purpose of overlay the Overlay is further categorized into Wear Resistance Overlay / Hard facing Overlay (example: Stellite 6 , Stellite 21, etc.) and Corrosion Resistant Overlay (SS 316 L, SS 308L, etc).
Step 1 : Select the Base metal P Number from Table QW/QB-422 , if not listed in the Table then state ‘unlisted’
Step 2 : Select the F Number for Filler Metal form Table QW-432, if not listed then state ‘ unlisted’
Step 3 : Select the A Number for Weld metal form Table Table QW-442.
Step 4: Select the test coupon thickness as per the Production material thickness, refer Table QW-453, The Test Coupon dimension shall be 150 x 150 mm of required thickness.
Also refer clause QW-214 for Corrosion resistant overlay
And QW-216 for Wear Resistant Overlay.
Example 1: for production of material with base metal thickness from 6mm to 50 mm, a test plate of 6mm should be selected
Example 2: for production of material with base metal thickness from 25 mm to 100 mm, a test plate of any thickness over 25mm shall be selected,
A Weld Clad seam of width 36mm minimum should be made at centre of plate for a length of 150mm.
The height of weld bead shall be the minimum height required in the production weld for Corrosion resistant overlay and minimum height required + additional 1.5mm of the production weld for wear resistant / hardfacing overlay.
Step 5: After Completion of Weld Coupon and Complete Solidification period, a Liquid Penetrant Test shall be carried on the Weld and HAZ area.
Step 6: The samples shall be machined and Tested as per the requirements stated in the Table: QW-453.
For CRO Corrosion Resistant Overlay- 4 Bend Tests required.
For WRO- Wear Resistant Overlay – 3 Hardness reading and 1 Macro Tests required.
Step 7: Prepare a PQR with recorded variables including the essential variables details as mentioned in the Standard and WPS shall be prepared.
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