CAT 785 dump bodies repaired and rebuilt on site

01

The challenge

Mining dump bodies in Mongolia degrade fast. Heavy payloads, abrasive material and thermal cycling wear structural elements beyond tolerance, and once winter arrives the repair environment itself becomes the harder problem.

Cold affects weld procedure control and how the base metal behaves. Wind and snow disrupt site access and inspection windows. Downtime is tight: every hour a truck sits in the bay is production the mine does not get back. And cold-weather welding is unforgiving: without strict preheat and interpass temperature control, structural integrity suffers.

02

Scope of work

The programme covered the end-to-end structural restoration of CAT 785 dump bodies across Energy Resources’ fleet, with repairs sequenced around the mine’s operating schedule to limit the effect on production.

• Damage assessment across the fleet, prioritised by severity, availability and operational criticality
• Non-destructive testing (NDT) matched to each defect type before repair planning
• Structural repair: damaged sections removed to sound base metal, welded to qualified procedures and reinforced at high-stress zones
• Wear plate repair where required
• Quality assurance: hold points before, during and after welding, with progressive NDT and dimensional checks for distortion

03

The AASM approach

• Condition-based priorities

  Each truck’s status (working, parked or on standby) set the repair order, so effort went first where it had most effect.

• Controlled welding

  Controlled sequences, backstep technique, fixturing and strict preheat and interpass control managed heat input and distortion in sub-zero conditions.

• Root causes, not patches

  Repairs addressed why a crack formed. Daily 5S housekeeping, end-of-shift clean-down and secure consumable storage were mandatory.

04

Two shifts, day and night

The programme ran on structured day and night shifts, which is what kept it within Energy Resources’ operating windows.

• Day shift

  Main repair and welding work, quality hold points while light and temperature were best, coordination with Energy Resources and receiving materials.

• Night shift

  Continuation welding within approved parameters, preparation and fit-up for the next day, grinding and cleaning, and lower-risk tasks.

• Every shift change was documented: a written log of progress, photographs of the current state, open defects, quality hold points and the next shift’s priorities and material needs.

05

Quality, safety and documentation

Every repair followed the same progression:

• Pre-start controls: permit to work, job safety analysis, toolbox talks, barricades, lock-out, fire watch and night-work lighting
• Inspection and damage mapping, with photos, crack mapping and thickness gauging
• Repair engineering: zones, reinforcement, weld specifications and distortion control
• Preparation to sound base metal, fit-up and preheat
• Controlled root, fill and cap passes with recorded parameters
• Post-weld inspection, final NDT, dimensional verification and return-to-service sign-off

06

Safety, risk and records

• Safety

  Clear accountability from site manager to field supervisor to the crew, regular audits and a risk assessment for every new task. Cold-weather protocols, warm-up facilities and suitable protective equipment were part of daily work.

• Risk register

  Reviewed weekly with Energy Resources: winter welding, distortion, night-shift fatigue (high-risk work kept to day shift), material lead times, fire, snow-related access delays and weld defect response.

• Daily and weekly reports

  Welding metres and zones completed, timestamped photo logs and shift handovers; weekly completion by truck, risk updates and safety records.

• A record for each truck

  Welder and procedure references, consumables, temperatures, NDT results and weld repair maps, with as-repaired drawings, return-to-service certification and recommended inspection intervals.

07

Where it stands

Work began in October 2025 and continued through the Mongolian winter. The assignment is complete, and the team has continued to support Energy Resources with bucket repairs and other site work.