Determining hydrogen content in metallic components 03 April 2019

HELIOS III FASTENERS is an innovative instrument able to measure the diffusible hydrogen in steel components such as fasteners, bolts, springs, nuts, etc, using a hot gas extraction method.

Manufactured by Italian-based Letomec Srl, HELIOS III FASTENERS is being presented to the fastener market by its official worldwide distributor – Glomax Srl. The HELIOS III FASTENERS carries out a test where a sample is heated at a constant temperature in a furnace chamber in order to produce the desorption of the hydrogen. The instrument is also equipped with a solid state sensor that is able to measure the hydrogen content in air. The air containing the desorbed hydrogen is therefore pushed through the sensor by means of an air pump.

Compared to other devices available for similar tests, HELIOS III FASTENERS has the following advantages:

  • The testing procedure is safe and simple – the instrument does not require substances such as mercury, glycerin or silicone oils.
  • The device is robust – no fragile components such as glass crucible or borosilicate cell, are involved.
  • Low costs for the use and maintenance – carrier gas and dehumidification columns are not required.
  • Low test time – customised furnace so that any potential object, regardless of size or shape, and even coated, can be measured.
  • Fast analysis – test for elaboration depends only on the size of the specimen.
  • Easy calibration – calibration can be performed at every temperature using a certified kit able to produce different hydrogen concentration in the air.
  • Easy to use – the system has a user-friendly software interface.

“The automotive, aerospace and construction industries require steels having greater tensile strength in order to achieve weight reduction and to improve the mechanical performance of the products. However, the high strength steels are typically affected by hydrogen embrittlement,” explains Letomec. “Assessing the structural integrity is becoming mandatory to measure the hydrogen content. The HELIOS III FASTENERS can become the basis for developing methods able to evaluate the hydrogen content in fasteners by quantifying, for instance with proper indices, the risk of delayed fracture in service.”

Deputy Editor

Claire Aldridge Deputy Editor t: +44 (0) 1727 743 889


Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.

Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.