https://mechcalc.net/blog/en/tags/fitness-for-service/ Recent content in Fitness-for-Service on MechCalc how-to Guide https://mechcalc.net/blog/og-default.png https://mechcalc.net/blog/og-default.png Hugo en Fri, 26 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-annex-d-misalignment/ Fri, 26 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-annex-d-misalignment/ When two plates or shells to be welded together are 'not aligned' (axial misalignment or angular distortion), the load path of a tensile load is forced to bend, adding a layer of local bending stress σs at the weld. BS 7910:2019 Annex D is a look-up handbook: it gives a formula for each of 10 standardized misalignment configurations (7 butt-joint types + 3 cruciform types), letting you compute σs directly from the geometry, or convert it to a stress magnification factor km to feed into the Annex M stress intensity factor and the Clause 7 fracture assessment. This article gives the physics, then a figure and algorithm for each type. https://mechcalc.net/blog/en/posts/bs7910-a533b-llaw-fad-walkthrough/ Wed, 24 Jun 2026 10:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-llaw-fad-walkthrough/ One of the four A533B-1 welded-plate problems: the LLAW specimen — as-welded, −120 ℃, low load ratio. It is the first of the four to fracture (1.27 MN). This post walks step by step through entering, computing, and reading the FAD in mechCalc's BS 7910 Clause 7 Fracture Assessment Calculator, to see exactly how the residual K_I^S of 46 MPa·m^0.5 pushes the assessment point to K_r=2.59, far beyond the Failure Assessment Line. https://mechcalc.net/blog/en/posts/fitnet-ffs-overview/ Wed, 24 Jun 2026 00:00:00 +0800 https://mechcalc.net/blog/en/posts/fitnet-ffs-overview/ In the fracture-mechanics and fitness-for-service (FFS) literature, FITNET is a name you cannot avoid. This article traces the origins of the FITNET EU project from public sources: how it descends from SINTAP, who led and funded it, its scale, what the four modules of the FITNET FFS Procedure each cover, and why its fracture module is highly comparable to BS 7910. https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-stress-fad/ Tue, 23 Jun 2026 00:00:00 +0800 https://mechcalc.net/blog/en/posts/bs7910-a533b-residual-stress-fad/ A set of large welded A533B-1 steel plates tested in four-point bending to fracture, built to answer a question engineers keep asking: where exactly does welding residual stress push the assessment point on the Failure Assessment Diagram (FAD)? We first lay out the background and the shared method, then break the four specimens (LLAW / LLHT / HLAW / HLHT) into four problems, give the FAD inputs and results for each, and re-run everything independently with mechCalc's BS 7910 Clause 7 fracture assessment, cross-checking point by point against the original literature. https://mechcalc.net/blog/en/posts/ffs-intro/ Fri, 19 Jun 2026 12:00:00 +0800 https://mechcalc.net/blog/en/posts/ffs-intro/ FFS in one minute: can a structure with a flaw keep running? What methods do engineers use to decide?