Open Cut

Chronic Problem Areas, Repair Quality and Improved Repairs for Dragline Structurals

Open Cut » Maintenance & Equipment

Published: November 03Project Number: C11052

Get ReportAuthor: Daya Dayawansa, Brian Kerezsi, Gerard Chitty, John Price, Henry Bartoseiwicz | MTI, Monash University

The chronic failures and repairs of field plant structurals have been investigated with a particular emphasis on BE1370 and Marion dragline structurals. The investigation steps included:

  • Review of history of structural failures, their classification and mapping (global and localised) of the location and type of failure
  • Review impact of the failures and repair on the basis of maintenance cost, downtime and safety
  • Review of present repair practices and techniques and their effectiveness
  • Review and identification of best practices (including those successfully applied across other industries)
  • Definition of factors contributing to selected critical chronic failures (e.g. boom clusters)
  • Detailed investigations to validate the main contributing factors
  • Development of guidelines for improved repairs for the chronic failures

The maintenance cost analysis, covering a period of ten years for eleven BE1370 and five Marion 8050 draglines, revealed that BE 1370 booms are the highest cost item in structural maintenance, followed by tubs. The BE 1370 boom repair cost is more than three times that of Marion 8050 boom repairs. In the case of Marion 8050 machines, the highest structural repair cost item is the tub repairs. The cost of unscheduled down time was several fold higher than the direct maintenance cost. In addition to the maintenance and downtime cost, the catastrophic failure risk emanating from chronic failures is highest for the boom. Based on this information, and with the agreement of the industry monitors for the project, the investigation focussed on the chronic cluster repairs of BE dragline boom clusters as the most critical area. The tub repairs, the second highest item identified through the cost analysis, were also investigated, albeit to a lesser degree.

The major factors influencing the BE main chord cluster cracking were identified at the early stages of the study and can be summarised as follows:
  • High stress ranges in clusters (compressive for most clusters)
  • High tensile residual stresses (as high as yield stress) causing the compressive stress ranges to become effective tensile stress ranges
  • Quality of initial fabrications and repairs, particularly at the root pass of the lacing to main chord welds.

Improving any one of the above factors can contribute to an improvement in fatigue life of the cluster, but optimal results may be obtained by improving all three of these together.

The repair history showed that the most common remedial measure taken is to reduce the stress ranges in the main chords by increasing the chord wall thickness. This approach provided an improvement, but was of limited value if the other factors were not addressed. Therefore, minimising the residual stress effects and improving repair quality should be given higher emphasis in order to improve fatigue life of the clusters.

The measured and simulated stress ranges in the main chords of BE 1370 and Marion 8050 machines have been carefully examined. For similar RSL's the main chord stress levels in BE 1370 main chords are slightly higher than that in Marion main chords. However, the cluster failures in BE 1370's are several fold higher than that for Marion 8050 machines. The major reasons for the difference are the quality of initial fabrication and the residual stresses. By nature of the overlapping BE cluster geometry, it is difficult to achieve the same level of quality that is possible in Marion clusters.

The clusters more prone to cracking have been identified using history information and the results of FE analysis. The main areas in a cluster where cracking is common have also been identified for focussed attention during fabrication and repair. The investigation also shown that the welding sequence of lacing members did not have a significant influence on the stresses observed in these clusters.

The detailed investigations into repair quality indicated that the specifications in the BE Tubular Manual for fabrication and repair are reasonable, but the quality achieved in practice, particularly in cluster repairs, had not been satisfactory. The main reasons for this appear to be: lack of emphasis on quality; conditions under which the repairs are conducted; and the need to complete the repairs within a very short period of time to get the machine back to work. The desirable level of quality for specific application should be determined by individual operators on the basis of commercial and technical considerations.

As residual stress was identified as a major factor affecting fatigue life of the clusters, a detailed residual stress measurement program was undertaken to quantify the levels of residual stresses. These measurements showed very high levels of residual stresses in the clusters that can significantly affect the fatigue life of the clusters.

The key recommendations from the project can be summarised as follows:
  • Identified critical locations in clusters for improved fabrication quality
  • Improved weld details for critical areas in BE 1370 clusters
  • Improved weld procedure for repairs - temper-bead welding
  • Improved guidelines for window repairs

The recommendations are detailed in Section 11 of this report.

The project has significantly improved the knowledge and understanding on dragline structural failures and repairs, through a series of systematic and detailed investigations. The recommendations given were formulated based on this new knowledge and understanding. The implementation of these recommendations should significantly reduce the structural maintenance and downtime cost of draglines.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C25060Development Of Borehole Shear Monitoring Device For Routine Application In Coal Mine Roadways

This project outlines the development of a cost effective, routine s...

C26063Reliable Estimation Of Horizontal Stress Magnitudes From Borehole Breakout Data

The main objective of the project is to develop a reliable and simpl...

C26053Predict Stress State And Geotechnical Conditions Near Major Geological Structures Using Microseismic Technology And Distinct Element Modelling

Stress state and geotechnical conditions often change significantly ...


Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C25031Developing Closure Criteria For River Diversions: An Alternative To Reference Sites

The use of reference sites for establishing closure criteria in area...

C27074Tyre Integrity Monitoring

Driving mine trucks with underinflated and overloaded tyres subjects...

C26034Coking Properties Deterioration In Small Samples

Accurate evaluation of coking coal parameters at the exploration sta...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C25019Adaptation Of Coal Grain Analysis To Improve Flotation Yield Estimation

This project involved sampling of full-scale flotation circuits at ...

C250083D Flotation Of Fine Particles

In this project a process for the continuous, selective agglomeratio...

C26009Improved Precision Of Determining Coal In Urban Dust

Dust samples collected in coastal locations using High Volume Air Sa...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C26044Physical And Chemical Interactions Occurring During Cokemaking And Their Influence On Coke Strength

This project builds onto a previous project , C24055 in which macera...

C27056Imaging Gas Penetration Inside Coals And Cokes And Determining Influence On Coke Reactivity

The suitability of cokes for use in a blast furnace is determined by...

C26045Mineralogy Effects On The 3D Porosity Evolution Of Coke And Coke Reactivity

CRI/CSR CO2 combustion data are key metrics of coke quality and perf...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C27058Technological Assessment Of A Recycle Reactor For VAM Abatement

Underground coal mining emits high volumes of methane, diluted in ve...

C27008Selective Absorption Of Methane By Ionic Liquids

The connection of a ventilation air methane (VAM) abatement plant di...

C24061Proof-Of-Concept Photocatalytic Destruction Of Methane For Coal Mining Fugitive Emissions Abatement

Australia's fugitive emissions in 2015 were 41 Mt CO2-e (representin...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community


National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook