During the past 40 years, the Oil & Gas industry has progressively transitioned from relying upon good workmanship standards for weld flaw acceptance criteria to the use of Engineering Critical Assessments (ECA). ECAs are a Fitness For Service (FFS) assessment that has become increasingly important in mitigating and preventing pipeline failures.
Through ECA analysis we can both assess the structural integrity when unexpected flaws are discovered in structures and also generate welding procedure flaw acceptance criteria for manufacture.
ECA’s are designed to evaluate the significance of any flaws within a structure or component with respect to structural integrity by assessing fracture, plastic collapse and fatigue growth and under specified loading conditions throughout its design life. These techniques can provide FFS assessments for projects with a range of installation methods and operational environments.
Engineering Critical Assessment (ECA)
During the past 40 years, the Oil & Gas industry has progressively transitioned from relying upon good workmanship standards in welding acceptance criteria to the use of Engineering Critical Assessments (ECA). ECAs are is a Fitness For Service (FFS) assessment that has become increasingly important in mitigating and preventing pipeline failures. On the one hand they have become an essential tool in witnessing welds subject to automatic inspection techniques in a production environment and on the other, an aid to determining structural integrity when unexpected defects are discovered.
ECA’s are designed to evaluate the significance of any flaws within a structure or component with respect to structural integrity, achieving this by determining the maximum flaw size that can be tolerated with respect to fracture, fatigue growth or plastic collapse under specified loading conditions within its intended design life. These techniques can provide FFS assessments for projects with a range of differing installation methods and operational environments, including deep, intermediate and shallow waters.
To successfully deliver an ECA, a multidisciplinary approach must be taken at all times, involving materials engineering, fracture and fatigue analysis and NDT expertise. Element’s ECA services are fully integrated, with its advanced materials testing facilities in Houston, Aberdeen and Breda assisting in the production of essential materials input data, delivered to internationally recognised codes and standards.
High quality data and analysis within an integrated service ensure more reliable modelling of installation and service conditions, thus optimising weld flaw acceptance criteria and minimising costs and time spent on unnecessary repairs, while ascertaining overall integrity of the pipeline. This is why Element's material testing, bespoke acquisition and analysis routines are tailored to provide the highest quality data in the Oil & Gas industry.Innovation in ECA testing and analysis methods is constant and remains an ongoing strategic priority for Element. An integrated, internationally standardised service from partners with equal expertise in both the testing and assessment areas of ECAs will provide benefits in terms of data and analysis accuracy, speed of delivery and cost whilst giving increased confidence in the overall integrity of a pipeline.
Any solid material can be tested for fatigue, but those metals and materials that are used in the Aerospace, Oil & Gas, and Automotive sectors are held to rigorous standards of quality for quality reliability and safety reasons.Element's fatigue testing services help companies in these and other industries meet quality requirements and create safer, stronger, more successful parts and products. Our Engaged Experts are trained in a variety of fatigue testing concepts, standards, and methods. These include:
- Mechanical fatigue
- Structural mechanics
- Strain gaging
- Multiaxial fatigue testing
- Stress corrosion cracking
- Low-cycle and high-cycle fatigue testing
- Life-prediction methodology
- Structural component life prediction methodology
- Low-cycle and high-cycle fatigue testing
- Thermo/mechanical fatigue testing
- Through zero (i.e., tensile/compression)
- Testing in environments (temperature or solution)
Fracture Mechanics Testing
Fracture toughness is a property, denoted KIc, which describes the ability of a material containing a crack to resist fracture, and is one of the most important properties of any material for virtually all design applications. A fracture toughness test characterizes the resistance of a material to fracture in a neutral environment and in the presence of a sharp crack.
Element engineers use Fracture Mechanics to quantitatively establish allowable stress levels for new structures, and inspection requirements for structures used beyond their initial design life. Our Engaged Experts test both high-strength ferrous and nonferrous materials in the company’s computer-controlled servo-hydraulic test frames.Element fracture mechanics lab experts can help you solve fracture toughness problems in your industry—from ground vehicle, aerospace, and defense suppliers to the power generation sector and nuclear and wind power industries,
The methods we use include:
The KIC test and the KIC value
In contrast with Charpy Impact Toughness, which can only be used to compare the notch toughness of materials or to determine a metal’s compliance with a specification, the KIC test, sometimes referred to as KIC, or K1C, is used to determine the fracture toughness of metallic materials. Most often associated with ASTM E399, the Linear-Elastic Plane Strain Fracture Toughness test, or KIc value, can be used directly, across a range of temperatures, to determine design, life calculations and crack growth, or remaining life calculations.
The CTOD test and the S value
Crack Tip Opening Displacement is a measure of the physical opening of the fatigue crack tip at the point of failure. Typically used to measure the toughness of materials that tear before failure. All tests can be carried out from -129ºC (-200ºF) to 200ºC ( 400ºF)
The JIC test
This is a determination of toughness using the energy expended in fracturing the sample.
The JR test
Using single or multiple samples, a value of J at the point of the initiation of tearing is determined.
Finite Element Analysis (FEA) Services
The various Finite Element Analyses available from Element include:
- Static Stress Analysis
- Design Optimisation
- Non-Linear Stress Analysis Including Large Deformation and Contact
- Time Dependent Analysis for Long-term Response (Creep, Stress Relaxation)
- Crack Growth Modelling (J-Integral, Cohesive Zone, Virtual Crack Closure Technique)
- Fatigue Life and Durability Analysis
- Damage Tolerance and Effect of Defect of Composite
- Dynamic Analysis Including Frequency and Vibration
- Impact Analysis and High Rate Deformation
- Engineering Critical Assessment of Structures
- Thermal/Heat Transfer Analysis
- Fully Coupled and Uncoupled Thermal-stress Analysis
- Fluid Diffusion/Permeation into Polymers
Element have a proven track record and experience assessing a variety of different installation methods routinely encountered within pipe laying activities including:
- Landline Installations
- J-Lay Installations
- S-Lay installations
- Reeling Installations
Element have a proven track record and experience assessing a variety of different operational conditions pipelines are routinely subjected to during their lifetimes:
- Vortex induced vibration (VIV)
- Vortex induced motion (VIM)
- Wave induced motion (WIM)
- High fatigue steel caternary risers (SCRs)
ECA Related Codes and Standards
Element can execute ECA analyses to a variety of internationally recognized codes and standards.
BS 7910 / Crackwise
BS 7910 is a widely used industry standard to facilitate the performance of ECA analyses. Element is represented on the materials properties panel of BS 7910 and is actively involved in the continuous development of this standard.
BS 7910 contains a comprehensive philosophy for carrying out ECA analyses for materials subjected to fracture, plastic collapse and cyclic fatigue growth. All the validated formulae used for these assessments are incorporated within the generic software package Crackwise where this software is a recognized industry standard. It is prudent to note that although validated this software is generic and therefore does not produce an integrated method to carry out a full ECA.
Element provides an integrated service to perform the testing and analysis in accordance with the various ECA methods outlined in BS 7910.
DNV-OS-F101 is a widely used industry standard detailing the ECA approaches and testing regimes required to perform ECA analyses for submarine pipeline systems subjected to a number of commonly used installation and operational conditions.
Element provides an integrated service to perform the testing and analysis in accordance with the various ECA philosophies outlined within DNV-OS-0F101 Appendix A.
API 1104 Annex A option 1 and 2 analyses. Element can identify and perform the associated testing to enable these ECA analyses to be performed. These approaches are commonly used for land line installations subjected to minimal fatigue.
Element also contributes to the ongoing development of many of these globally recognize international standards through the involvement of our Engaged Experts in a number of industry leading steering groups and committees
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