Nickel Sulphide

What is Nickel Sulphide? (NiS)

Nickel Sulphide (NiS) is a contaminant that can be found in glass and possibly lead to glass failure.Generally only tempered (toughened) glass will contain this as a potential risk.

A Nickel Sulphide inclusion in the glass structure can change state at an unspecified point causing total failure of a pane. Considerations for owners and tenants of a building that may contain Nickel Sulphide:

  • Public safety
  • Workplace Health and Safety
  • Tenant issues
  • Media interest
  • Insurance and litigation
  • Building’s value

What JPW Osprey Limited can offer to clients/tenants:

  • Specialist advice and consultancy through 30 years of experience
  • Testing and reports (providing glass samples are available)
  • Suggestions & solutions
  • Full package of remedial works as a principal contractor
  • CDM compliant, dealing with the local authority and all aspects of Health and Safety
  • Works carried out with minimum disruption to the buildings occupants or the general public

Through the glass manufacturing float process small particles can be included within the body of the glass. These small inclusions may often not be visible to the naked eye but will sit harmlessly within the glass make up.

There are several processes that change the strength or breakage characteristics of glass that make the glass safer to use. One of these processes is toughening (typically making the glass 10 times stronger). This process is carried out in a toughening furnace where the glass is heated to between 600–700 degrees.

The outer surfaces of the glass are then cooled more rapidly than the inner body which creates a surface tension, giving the glass its additional strength. This energy will only dissipate if the glass surface tension is broken. A nickel sulphide inclusion (typically metal of potentially 100μm = 1 tenth of a millimeter) can sit harmlessly within the glass for many years and may never create a problem. However, the Nickle Sulphide particle can change shape at any time and create stresses within the glass to a point where the glass shatters spontaneously. Since the early 1980’s heat soak testing has been offered by suppliers as a means of finding Nickle Sulphide and causing early failure.

This process needs to be carried out with specialist heat soaking ovens to defined standards with accurate processing records being kept. Heat soaked toughened glass should be stamped EN 14179, whereas toughened glass without heat soaking, should be stamped EN 12150. With the increased availability of heat soak testing, the problem of Nickle Sulphide has appeared to have been declining, however over the past few years with the increased trade in unregulated and cheaper glass the problem seems to be on the increase.

JPW Osprey Limited have carried out numerous repairs and replacements for clients. Many of these as the main principal contractor, dealing with the local authorities securing access licenses, planning, supplying and installing all materials, with minimum disruption and often working out of hours to accommodate the building’s occupants or tenants.

JPW Osprey Limited work closely with the industry’s major suppliers to provide the best possible design and solution. Note:

  • Heat soaking does not eliminate risk, but substantially reduces it;
  • The presence of Nickle Sulphide does not always lead to glass failure;
  • Nickle Sulphide may only be identified as the cause of failure by laboratory examination of the origin of the break;
  • Heat soaking is not mandatory and may not automatically be offered by the glass supplier. It is up to the specifier to include heat soaking where appropriate.