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Why does NDT data need upgrading?
NDT inspection data for visual type inspections of in-service equipment have remained the same for more than half a century.
Industry has evolved, with a greater focus on maintenance and reliability. It is time for NDT data to catch up and provide the information that is truly needed for risk management and repair management. Simply providing visual crack length is insufficient for these purposes.
Please contact us if you have any questions or if you want to implement the Crack Data System
For example, consider a nominal 200mm crack that is found in a chassis or boom. In reality, this 200mm crack may be any of the following;
A 200mm crack that is 5mm deep in 25mm plate
A 200mm crack that is 15mm deep in 25mm plate
A 200mm crack that is full thickness through 25mm plate
A 200mm crack that is full thickness through 25mm plate but has propagated from the internal side, with an internal length of 500mm
A 200mm crack that is in a Non-structural element compared to one that is in a Vital location
A 200mm crack at the weld toe compared to transverse crack through a corner weld.
There is a significant difference in the level of risk presented as well as the repair requirements for each of these cracks in terms of repair duration, welder competence and also quality assurance and control.
It is clear that traditional NDT data is severely lacking. This is why the Crack Data System was developed.
Overview
The Crack Data System fully describes the following key features of cracking that are relevant for risk management and repair assessment:
The location where the cracking is in terms of risk to asset operation
The nature and features of the cracking
Whether the cracking is internal or external initiation
Length of crack on internal side (of hollow sections)
Length of largest individual crack in a zone of cracking
Depth of cracking
Thickness of the material
Generate standardised thresholds based on crack length for the various location types. See this link for more details.
Assess the risk at a glance based on the location type
Vital, Structural or Non-Structural
Better estimate the time required to carry out the repair based on the total repair volume (length, depth and material thickness)
Allocate the right welder to the repair to ensure it is done right
Crack Location Type
By simply categorising as Vital, Structural, or Non-Structural, it makes it easier to know how important a crack is.
Also, standardised threshold values can be developed for condition severity based on the location type.
Crack Dimensions
Total Length - Overall visible length is all that is typically reported from NDT inspections
Maximum Length - Informs whether there are a number of smaller cracks that make up the larger, and also enables estimating of crack depth. This is also used to indicate crack length internally.
Thickness - Knowing the thickness of the section that is cracked is important for estimating the repair duration, as well as assisting the Welder in knowing how deep to gouge.
Nature of the Cracking
Location - Better understand and manage risk
Type - The nature of the cracking assists in understanding the cause, risk, and how to repair it
Depth - Simple categorisation of depth allows improved risk management, as well as making it easy to assign a Welder with the appropriate competency for the repair.
Crack Examples
Location
The location of a crack is important! with the Crack Data System you don't need to look through photos to be able to know where cracking is in order to manage risk and determine your repair priority
V200LF25
200mm long crack that is full thickness in a Vital location in 25mm plate
S200LF25
200mm long crack, at the weld toe, full thickness in a Structural location in 25mm thick plate
N200LF25
200mm long crack, full thickness in a Non-structural location in 25mm plate
Crack Type
The nature of the cracking is important for determining the repair plan and methodology. Also, knowing the type of cracking allows a deeper understand of the potential causes of cracking.
S200LP25
200mm Longitudinal crack that is parallel with the weld, partial depth in a Structural location in 25mm plate
S200TP25
200mm crack that is Transverse to the weld, partial depth in a Structural location in 25mm plate
S200I30P25
200mm long Intermittent crack, with the largest individual crack being 30mm, partial depth in a Structural location 25 mm thick
S200M30P25
200mm long zone of Multiple cracks, with the largest individual crack being 30mm, partial depth in a Structural location 25 mm thick
S200X120F25
200mm total length of Complex cracking (branching, intersecting, propagating through multiple plates etc), with the maximum individual crack length of 120mm, full thickness in a Structural location 25mm thick.
S50XP25
The “X” can also be used to indicate cracks that are inaccessible for repair without major equipment disassembly.
Depth and Thickness
Cracks are 3 dimensional. Knowing the depth and material thickness allows more accurate estimates of required repair duration for planning purposes. It also allows simple welder competency requirements to be established based on whether the crack is full thickness in a hollow section.
S200LS25
200mm long crack, at the weld toe, shallow depth (<5mm) in a Structural location in 25mm thick plate
S200LP25
200mm long crack, at the weld toe, partial depth in a Structural location in 25mm thick plate
S200LF25
200mm long crack, at the weld toe, full thickness in a Structural location in 25mm thick plate
Internal Cracking
S0L200P25
No visible cracking at external surface (0mm), but 200mm at internal surface (eg weld root), partial thickness in a Structural location in 25mm thick plate. This is typical of cracking found via Ultrasonic Testing
S200L500F25
200mm long crack in the weld cap, and 500mm along the weld root (cracking from internal), full thickness in a Structural location in 25mm thick plate.
Example Inspection Report
The Crack Data System can easily be used by your NDT service provider or Condition Monitoring team and presented in their inspection reports
Hitachi EX5500 Inspection Report Example.pdfPlease click this link if the document does not load in this page
About the Crack Data System
As part of our mission to improve crack repair management, WQMS developed the Crack Data System to upgrade NDT data so that the necessary information is provided for risk and repair management
The Crack Data System is OPEN SOURCE. Why? Because good things need to be shared, and everyone will benefit from using the Crack Data System. It is a foundation for our AICARM Framework, and supports the Mining Welder Competency, but it can also be used to great benefit just by itself.
What's the catch? There is none. We are making all the basic information for the Crack Data System publicly available. However, formal training of NDT technicians is recommended. Basic training may also be helpful in introducing the Crack Data System to site and familiarising maintenance personnel with how to use it
Want to know how to implement it? - Call us for free advice 02 5516 1008 or send us an email info@wqms.com.au
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