Becht Engineering Blog

In this section of the site contributing authors submit interesting articles relating to the various services, industries and research & development efforts of Becht Engineering.
Becht Engineering staff are experts in piping, and include former chairman of various ASME piping committees, including ASME B31.3. Becht Engineering performs detailed design for complex piping systems including very high temperature and pressure systems such as piping for FCC flue gas expanders and high pressure LDPE systems, as well as design, a...nalysis, troubleshooting and fitness for service evaluation of piping. More

Grade 91 Steel - How Did We Get Here? Part 3

grade91_cover-image
Read Part 1 or Read Part 2 Part 3: Allowable Stresses While inspectability has been at the center of recent concerns, other issues such as chemistry control, ductility and excessive oxidation have also come under scrutiny.  Perhaps most interesting is that while all of the preceding concerns have been debated, it has also been found that existing ASME allowable stresses for Grade 91 are not conservative relative to newer data techniques.  This is beautifully illustrated in Figure 5 from [2], where the continual drop in allowable stress is plotted as more and more short term test data is removed from the analysis.  The good news is that “new” material is not worse than older material (at least from a statistical and data analysis perspective).  The bad news, as discussed in [2] and can be seen in Figure 6, is that even more modern techniques like “region-splitting” do not capture the apparent...
Continue reading
2
  251 Hits
  0 Comments
251 Hits
0 Comments

EPRI Publishes "Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping"

epri-logo
EPRI has just published the report “Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping” EPRI report number 3002013156, dated December 2018, prepared by Becht Nuclear Services, under EPRI Project Manager T. Eckert. The methods and criteria for the evaluation of degraded and non-conforming conditions in piping systems in nuclear power plants are dispersed among a number of ASME XI Code sections, Appendices, Code Cases, and US NRC regulatory requirements, generic letters, and inspection manual sections. This multitude of requirements makes it necessary to have this roadmap to help the engineer make the right fitness-for-service evaluation and the right repair decision. The EPRI road map addresses the fitness-for-service evaluation methods and criteria for the two most common damage mechanisms in nuclear power plant piping systems: Wall thinning, and cracking. The roadmap also addresses non-conformance caused by overloads, i.e. operating loads that exceed the design loads. Regarding repairs of nuclear plant...
Continue reading
2
  219 Hits
  0 Comments
219 Hits
0 Comments

Restoring High Energy Piping System Performance by Reducing Friction

pipe_friction2 Damaged/Destroyed Low Friction Sliding Surfaces
"When You're Stuck, You're Stuck" Over years of normal operation - like cycling and wear and tear - High Energy Pipe support friction can increase causing distress in these critical systems. Friction is a common phenomenon which is widely understood and considered in both piping analysis and support design.  Generally, a piping analyst models a piping system with a friction coefficient on all base type supports of 0.3 for steel on steel or lower if a low friction sliding surface will be used, and hits “run” on his design software program.  The stresses are evaluated, loads on supports determined, and the analysis is off to support design.  The support designer takes the loads (which include friction) and designs the support.  No errors were made, the calculations are correct, and everything should work. But what happens in the field after years of operation and cycling? That depends on several variables, including the...
Continue reading
4
  663 Hits
  0 Comments
663 Hits
0 Comments

ASME B31.3 - Substantive Changes in the 2018 Edition for Process Piping

B31-3_ASME
In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2016 Edition of ASME B31.3, Process Piping, which is scheduled to be issued mid-January 2019. These substantive changes are: Owner Added specific permission for the owner to designate a representative to carry out selected responsibilities required by this Code, and noted that the owner retains ultimate responsibility for the actions of the representatives. Flange Design Added the ASME B&PV Code Section VIII, Division 2, para. 4.16 flange calculation method as an acceptable way to design flanges for B31.3 applications. The Division 2 procedure considers pressure, gasket seating, and externally applied axial forces and net-section bending moments. Stress Intensification and Flexibility Factors Added specific references to ASME B31J-2017 as a resource for stress intensification and flexibility factors as an alternate to Appendix D. High Cycle Fatigue...
Continue reading
6
  1710 Hits
  0 Comments
1710 Hits
0 Comments