Hydrogen embrittlement
Hydrogen embrittlement occurs as a result of exposure to hydrogen, for example, in the manufacture or processing of high-strength steels and titanium and aluminium alloys. It reduces the ductility and load-bearing capacity of affected materials, which can cause cracking or failure at below normal yield stresses.
Hydrogen embrittlement takes place when recently-produced, nascent hydrogen atoms diffuse into the metal. When load is applied, the hydrogen atoms migrate towards areas of high stress, and the resulting pressure causes sub-microscopic cracking. These cracks themselves become areas of high stress, and so the process continues and the cracks spread through the material, which can ultimately result in failure.
In November 2014, two large bolts fractured at the 47-storey, 737ft Leadenhall Building, popularly known as ‘The Cheesegrater’ because of its distinctive slanting profile, created to respect a protected sight line of St Paul’s Cathedral. A small part of one of the bolts fell from the fifth floor to the ground, but the area was not publicly accessible due to ongoing construction works and nobody was injured.
A third bolt then fractured but was captured by tethering which had been installed following the first two failures.
Investigations undertaken by contractor Laing O’Rourke and structural engineers Arup confirmed that the problem was limited to certain bolts. Tests concluded that the bolts had failed due to hydrogen embrittlement. Arup also confirmed that there was no adverse effect on the structural integrity of the building. However, a programme was undertaken to replace a number of bolts a precautionary measure.
In April 2019, Structural steelwork contractor Severfield released a trading update announcing that it had reached a final settlement with developer Leadenhall following “extensive negotiations”. Ref http://www.constructionmanagermagazine.com/news/severfield-settles-over-cheesegrater-bolts/
[edit] Related articles on Designing Buildings Wiki
- Brittle fracture.
- Corrosion.
- Degradation of construction materials.
- Failure of cast iron beams.
- Failure of metals.
- Graphitisation.
- Leadenhall building.
- Rust.
- Spalling.
[edit] External references
- Global Construction Review. Fear of failure: Why bolts on London’s Cheesegrater tower began to break. 16 January 2015.
Featured articles and news
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).