🧮 在线计算器：Bolt Pre-selection Calculator — Fast sizing with the Kübler equation; supports a design mode and a check mode. Preliminary sizing of a bolted joint: from load to size, fast Before getting into complex system-level bolted-joint calculations, the first challenge an engineer faces is often: “for a given working load, how large should the bolt be? Is M8 enough, or M12?” A sound preliminary design / pre-selection (German: Vorauslegung) quickly fixes a suitable nominal diameter and does an early “sweep” for common failure modes (such as fatigue fracture, or loss of preload from crushing of the bearing surface). This article shows how to do a quick pre-selection from the working load, and how to check the feasibility of the design with simplified formulas. ...

1. Overview The bolt (German: Schrauben) is the earliest and most widely used machine connection element in mechanical engineering. Compared with other connection methods, the bolt has the largest number and the richest variety of standardized forms. 1.1 The thread line on a bolt The core of a bolted joint is the form fit (German: Formschluss) between the bolt (external thread) and the clamped part (usually the internal thread of a nut). ...

1. Background: Appendix Y, from scattered to unified In nuclear fracture mechanics and structural integrity assessment, predicting how a flaw grows during service is the decisive foundation for justifying life extension or Leak-Before-Break (LBB). In earlier ASME BPVC Section XI editions, the reference crack growth rate curves for different materials were scattered across separate appendices: Appendix A: ferritic steels. Appendix C: austenitic stainless steels. Appendix O: intergranular stress corrosion cracking (IGSCC) of nickel alloys. In the 2025 edition of ASME XI, the code committee made a major structural revision: the growth-model equations for the various materials and mechanisms (fatigue $da/dN$ and stress corrosion $da/dt$) were all consolidated into the new Nonmandatory Appendix Y: ...

🧮 Go straight to the calculator: to skip the derivation and use the online tool with a built-in verification flow, open the fatigue crack growth calculator from the large category cards on the calculators home page. 1. Where fatigue crack growth sits in an LBB analysis At the core of a Leak-Before-Break (LBB) argument: you must show that, over the service life, the time for an initial non-penetrating surface flaw to grow by subcritical crack growth through the wall and cause a leak — and the time from leak to growth to the critical fracture size — is long enough for the monitoring system to detect it and act. ...

This article explains how to use the seven-step method of the KTA 3206 standard for a Leak-Before-Break (LBB) analysis of nuclear piping. It pairs with the KTA 3206 LBB Pipe Analysis module of the online calculator, taking you from theory to practice. 🧮 Try the calculator now: open the KTA 3206 LBB pipe analysis calculator , choose “Fracture Mechanics → KTA 3206 LBB Pipe Analysis”, and enter the parameters to get results with a detailed formula derivation and visual charts. ...

This is a detailed introductory guide to Leak-Before-Break (LBB). LBB is a crucial safety concept in the structural integrity assessment of pressure vessels and piping. In short, it is an analysis that proves the equipment will produce a detectable leak first, before any catastrophic fracture — giving operators time to shut down and avoid a major accident. 1. What is Leak-Before-Break (LBB)? Core definition: LBB is a property of a pressure-bearing system (pipe, vessel). It ensures that when a flaw (crack) is present, the crack will penetrate the wall to form a through-wall crack and produce a stable, detectable leak before it grows to the critical size that would cause overall structural instability (sudden fracture or plastic collapse). ...