High-Performance Bolting Technology for Offshore Oil and Natural Gas Operations (2018) / Chapter Skim
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5 Innovation Opportunities
5 Innovation Opportunities
Pages 90-124
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From page 90... ...
Specific opportunity areas include the following: new testing protocols (forensic evaluation of decommissioned fasteners, damage tolerant analysis using computational methods, and robust understanding of rare failure events) , in situ fastener measurements during service (in situ bolt load measurement, in situ bolt defect identification, in situ assessment of hydrogen contents in steels, in situ analysis of hydrogen and hydrogen-assisted cracking (HAC)
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From page 91... ...
This rigor ous bookkeeping could start with those fasteners securing the pressure boundary. Decommissioned connector testing can occur in a number of ways, as a met allurgically based failure analysis centered investigation aimed at identifying root causes of failures, fracture assessment using fracture mechanics and damage toler ance approaches, or by better hydrogen analysis and re-creation of embrittlement conditions under known hydrogen levels above and below those in service.
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From page 92... ...
Rough indications of crack growth rate are also possible based on service life, crack length (if detected) and various possible scenarios regarding crack initiation time.
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From page 93... ...
4 indow of Susceptibility -- a common logic in the stress corrosion cracking and hydrogen em W brittlement community is that some dependency space exists, usually define by metallurgy, chemistry, and fracture mechanics conditions where cracking occurs and other regions where cracking does not occur. This has been made popular by a Venn diagram of overlapping circles but it is clear that conditions are more complex.
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From page 94... ...
Crack growth rate (da/dt) increases with cathodic potential and the threshold stress intensity for environmental cracking KIscc, decreases.6 It can be seen that at potentials more negative than −800 mV SCE that crack growth rates are significantly enhanced above a Kth of about 15 MPa(m)
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From page 95... ...
Ha, J.T. Burns, et al., Measurement and modeling of hydrogen environment assisted cracking in Monel K-500, Metallurgical and Materials Transactions A 45:3814, 2014.
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From page 96... ...
. Data with longer failure times contained a lower hydrogen level.
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From page 97... ...
At the threshold stress intensity indicated in Figure 5.1, the lifetime approaches infinity. Value Proposition Such tools can be a valuable adjunct to other methods in predicting lifetimes of undersea bolts in environments where hydrogen uptake is likely.
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From page 98... ...
Robust Understanding of Rare Failure Events One of the challenges of bolt failures in the oil and gas drilling industry is the reported extremely low failure rate a product of the rare reported failures. Until an industry wide fastener inspection program finds more failures what is needed is a robust understanding of the causes of rare failure events in a large population of fasteners, which pending more thorough analysis might not have much HAC damage seen in the form of subcritcal cracks.
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From page 99... ...
Speller Award Lecture: Stress corrosion cracking in pressurized water reac P tors -- Interpretation, modeling, and remedies, Corrosion 56(8)
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From page 100... ...
Adaptation of this technology to subsea environments is prob ably not developed and therefore significant development would be required. In Situ bolt Defect Identification The Nuclear Regulatory Commission has experience with, and has qualified, existing technology that enables ultrasonic crack detection on underwater bolts 20 ee S the Load Control Technologies website at http://www.loadct.com, accessed October 11, 2017.
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From page 101... ...
In Situ Assessment of Hydrogen Contents in Steels During service, hydrogen can enter steel from the environment as modified by cathodic protection systems, interactions with corrosive environments (e.g., sea water) , and other potential sources.
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From page 102... ...
The hydrogen con centration results compared to similar data obtained on laboratory samples failed under controlled conditions with known hydrogen contents, could potentially be used to assess the probability of failure in installed connectors and guide planned maintenance. Feasibility Development of a technique for in situ hydrogen measurements will require significant effort as it has low probability of yielding near-term results.
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From page 103... ...
Friedersdorf, Luna Innovations, Inc., "LUNA, Compact Fracture Mechanics N Based Sensor for Monitoring Environment Assisted Cracking," paper presented at the DOD Allied Nations Corrosion Conference, 2011, http://lunainc.com/wp-content/uploads/2013/04/Luna-EAC sensor-DoD-Corrosion-2011.pdf. 32 e term "canary" comes from an analogy with the use of canaries to sense and provide early Th warning of dangerous gases in underground mines.
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From page 104... ...
Figure 5.4 shows the measured crack growth rate as a function of applied cathodic potential for two materials; Monel K-500 and 17-4 PH precipitation aged hardened stainless steel. The gal vanic couple potential to Zn and low-voltage anodes (LVAs)
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From page 105... ...
Fatigue Monitoring System A fatigue monitoring system is an instrumented system capable of monitor ing vibrations of risers to better estimate fatigue, and communicate results to the surface.36,37 Value Proposition Even though fatigue failures have not been noted in riser/BOP systems to date, fatigue is a critical design parameter for subsea equipment such as drilling risers that are exposed to cyclic loads from wind, waves, currents, and flow; vortex 36 prototype of such a system has reportedly been developed by Stress Engineering. This sys A tem reports the existence of vibrations.
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From page 106... ...
Questions such as long-term reli ability, accuracy, and wireless communication capability would also have to be proven, as well as the value proposition of cost versus benefit. Monitoring of Connector Integrity While the holy grail of connector integrity, real time monitoring, is achievable in the laboratory, the harsh undersea conditions make this ideal approach difficult as discussed in the examples above.
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From page 107... ...
IMPROVING THE HYDROGEN-ASSISTED CRACKING RESISTANCE OF BOLT ALLOYS Uncovering Sources of Embrittling Hydrogen in Fastener Materials One of the shortcomings that plagues a root cause analysis is unequivocal sourcing of damaging hydrogen that enters fasteners. Past fastener failures have been blamed on hydrogen not baked out in manufacturing.
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From page 108... ...
However, if intermediate strength traps retain hydrogen even after baking this hydrogen can then redistribute to sharp crack tips with high triaxial tensile stress, then a critical hydrogen level might be attained. This is due to the combination of residual hydrogen from the coating that is repartitioned and service exposure to cathodic protection.
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From page 109... ...
Raymond, Fracture and Stress Corrosion Cracking Resistance of C465, BioDur 108, SpT 13-8, K-Monel 500, and Zeron 100, Report #CTC'071024, L Raymond and Associates, Newport Beach, Calif., 2008.
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From page 110... ...
Value Proposition A high strength fastener material with high HAC resistance exhibited by high fracture toughness and high threshold stress intensity in the presence of hydrogen 48 .P. R Gangloff, "Hydrogen Assisted Cracking of High Strength Alloys," pp.
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From page 111... ...
These include grain boundary and interface engineering, use of bond promoters, use of gettering agents such as rare earth treatments perhaps integrated with a choice of an alloying element which forms an oxide film that functions as a permeation barrier. Computational approaches now exist for high-throughput searching for the best combination of alloying elements to achieve the above goals while maintaining desirable strength and toughness.
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From page 112... ...
The significance to trap and interface engineering against hydrogen assisted cracking is that the additional flux and accumulation of hydrogen may eventually saturate so called "saturable" trap sites or exceed the critical hydrogen coverage required for grain boundary fracture even if the interface engineered boundary requires an increased hy drogen coverage to trigger fracture. Each trap can fill in an open system independent of other traps if an equilibrium lattice hydrogen concentration is raised in response to severe cathodic protection.
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From page 113... ...
Kalucki, "Gas Nitriding and Gas Nitrocarburizing of Steels," in ASM Hand K book, Volume 4A, Steel Heat Treating Fundamentals and Processes (J. Dossett and G.E.
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From page 114... ...
Pye, "The Power of Pulsed Plasma Ion Nitriding," Heat Treating Progress, ASM International, D Metals Park, Ohio, July/August 2009.
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From page 115... ...
These are prevalent in aerospace but might lack the lifetime necessary for offshore service. Moreover, there are hydrogen permeation barrier coatings such as metal oxides that have low hydrogen diffusion rates; but these are often brittle.67 Oxide permeation barrier coatings are common today but provide no active protection mechanism for scratches which expose bare metal.68,69,70 There are a few multi-functional coatings for HAC resistance that are designed to serve several hydrogen resisting functions at the same time, perhaps in a mul tilayer format.
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From page 116... ...
and da/dtII were improved with the inhibiter at intermediate cathodic potentials. The coating might have barrier, potential control, and chemical inhibition capability all built into one coating.
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From page 117... ...
The challenge will be to identify elements, which will improve the adherence of the oxide for corrosion resistance under mechanical loading and an electric field. Value Proposition This is another example of coatings which may protect bolts used in undersea applications.
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From page 118... ...
Veedu, "Development of Nanotechnology Pipe Treatment to Improve Acoustic Cement Evaluation," Paper OTC-27893-MS, Offshore Technology Conference OTC 2017, 2017, http://www. onepetro.org/conference paper; E.P.
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From page 119... ...
Casioppo, "Nano Laminated Alloys for Improved Return on Oilfield Assets," SPE Paper 179923-MS, SPE International Oilfield Corrosion Conference and Exhibition, May 2016; Nano-Layers in metallic coating enhance its corrosion resistance, Material Performance, Vol 54, No.
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From page 120... ...
NEW FASTENER DESIGNS Alternative Thread Designs84 The 8-round thread design has been used successfully in oil and gas applica tions for years. This old technology may not extrapolate well to the extreme service requirements for deepwater drilling riser bolts.
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From page 121... ...
DuMay, "Effect of Blowout Pre F venter End Connections on the Pressure Integrity of a Subsea BOP Stack Under Riser Loads," Paper OTC-2649-MS, Offshore Technology Conference, May 3-6, 1976.
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From page 122... ...
89 . Burgess, "Bolt Manufacturing -- A Look at Critical Operations," presentation to the Workshop L on Bolting Reliability for Offshore Oil and Natural Gas Operations, April 10-11, 2017.
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From page 123... ...
• Action Plan. Establishing an industry function to review all nonproprietary aspects of the design, manufacturing, installation, operation, and maintenance of drilling riser systems and their components would allow non-technical, human-systems experts to have a "cold-eyes" look at these systems and suggest improvements.
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From page 124... ...
The oil and gas industry should have a strong role in determining the priorities of which ideas to pursue. BSEE, using the recommendations of the consortium, could also initiate research and development efforts for those innovations that may offer considerable safety advantages but are not currently available as products or systems.
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