APPLICATION REPORT | OFFSHORE AND SUBSEA LIFTING


embrittlement, who was not directly involved in the report’s findings. He noted, while the scientific community has achieved great progress in using simulation tools to predict the behaviour of components exposed to hydrogen, challenges remain. “There is a real concern across industry


regarding the impact of HE and SICC on chains and links used in hoist and lift products across offshore environments,” says William Hackett director Ben Burgess. “Based on our own experiences of how our products perform offshore, combined with the manufacturing expertise of chain makers McKinnon Chain and outcomes of detailed technical analysis by industry partners, we have identified that as material hardness exceeds 39-40 HRC, the risk of HE and SICC increases as the hardness values rise,” he continues, echoing the points made by Nyberg of Gunnebo. Available hydrogen, the material used and the stress placed on the component are all factors that contribute to hydrogen embrittlement (See Figure 1. opposite).


“The issue of HE is not limited to just one type of offshore activity,” says Burgess. “Examples include the failure of G10 welded chain slings in a container fleet in Norway. In the US, a global oil company had to withdraw a number of lifting appliances and promptly introduced an inspection regime before any future lift work was carried out. “Meeting the specific International


Standards should not be seen as a guarantee that specific equipment is fit for purpose in an offshore environment,” he says. “Specific environmental and performance considerations for equipment which is used offshore needs to be a key part of the material specification and selection process. “To put this into context, a Grade 8


master link, when correctly heat treated, will provide toughness, tensile strength and resistance to shock absorption in loading, and will do it at hardness levels that enable the steel in the product to withstand extreme conditions when in use in the offshore environment.”


R Fig 1: The material involved, the stress it is under, and hydrogen penetration all contribute to hydrogen embrittlement. Diagram: William Hackett.


Key areas around HE include causal


factors and best practice methods, says the report. Correct materials selection is critical. Operators need to ensure that despite commercial pressures the products used in the offshore environment are fully appropriate for their intended use, and that the environmental conditions, mechanical stresses and material susceptibility have all been assessed rigorously. “Managing the risks of HE and SICC


requires a change of mindset,” says Burgess. “The advancement towards higher grades of steel should be treated with caution. Without proper understanding of the material and its use offshore, the end result is increased risk to operations.” The company is well-known for its subsea SSL5 lever hoist with its patented Quad Pawl system, which we have covered in these pages before (see Hoist, April 2020). Its design and extensive corrosion protection give it multiple immersion capability, independently verified by DNV. William Hackett has taken further steps to help minimise the risks of HE and extend the lifespan of its master links with the introduction of Zinc-Tough, an innovation that applies a zinc layer to the product which significantly reduces the speed at which corrosion occurs. It extends the product lifespan and also reduces the risk of HE compared to other coating processes such as galvanising and electroplating. William Hackett to date has delivered more than 550,000 master links. “We are immensely proud of our track record in the supply of HA links to Shell, BP,


Q Master links from William Hackett on this maritime lift are coated against hydrogen embrittlement.


www.hoistmagazine.com | May 2021 | 31


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