Case study – Weld Repair Certification

BVT were approached to provide a certified repair procedure to a cracked forklift mast. Forklift masts form an important part of the system that allows the forklift to lift. Sudden failure of any part of this system could result in a dangerous situation as well as unplanned downtime. BVT were able to get out on site quickly, determine the nature of the damage and recommend a repair procedure to get the forklift operational and minimise down-time.

The Problem

The crack was in a critical area of the outer mast, if left unaddressed it would have propagated through the upright making the forklift physically unusable.The cracks were the result of fatigue at a stress concentrator. They were a recurring problem and had been repaired in the same place at least once before, however due to the poor weld detail and insufficient preheat the cracks had re-appeared. The repair we specified had to resist further fatigue as well as comply with AS/NZS 1554.4 Welding of high strength quenched and tempered steels.

The Solution

We consulted the manufacturer for their repair advice, which is standard practice for higher risk equipment and then verified this against AS/NZS 1554.4, this involved ensuring the materials, electrodes, joint preparation and preheat aligned with the requirements for a pre-qualified weld. The repair specified had to take into account the way the way mast was loaded and be as simple as possible for the fabricators. We then prepared a report that involved removing the damaged piece of mast and provided a Weld Procedure Specification (WPS) to weld the new part to the existing mast.