Chinese steel concerns

Serious concerns about the levels of Boron in steel imported from China.

The elected Chairman of the China Iron and Steel Association was quoted in the FT in February as saying: “China’s steel production has … hit a turning point” and the industry must shift its focus from expansion, to quality and efficiency. This is good news for fabricators, the construction industry, and members of the UK steel industry who have been concerned in recent months about steel that is imported from China into the UK, which does not meet required standards.

One of the main concerns about the imported steels is that they have raised levels of one or more of the following elements: Boron, Chromium and Copper. These elements are included in order to qualify the steel as “alloy” which benefits from an export tax rebate.

UK Steel, a member of The Engineering Employers Federation (EEF), recently issued a press release, which said:

“For the past few months it has become increasingly clear that some imported steel plates and sections from China are being supplied into the UK market which are not fully compliant with the requirements of the relevant standard. This follows earlier warnings regarding potential quality issues affecting Chinese concrete reinforcement bars.

“The EU specification for structural steel explicitly states that it applies only to “non-alloy steels”. To qualify as “non-alloy”, steel must comply with strict limits on the quantity of other metallic elements it contains. This “non-alloy” classification amongst other things ensures that the steel is readily weldable without the need to apply any special welding parameters.”

The Welding Institute, which is the leading professional engineering institution responsible for the professional registration and certification of welding and joining personnel worldwide, has issued guidance that rebar containing Boron in excess of five parts per million requires changes from the normal welding process. However, a significant (but unknown) proportion of the Chinese rebar sold in the UK contains Boron in excess of eight parts per million. Samples have even been tested with Boron at 30 parts per million.

UK Steel, also spoke in their press release about the potential problems that might be encountered when welding or heat treating certain steels (plates and sections) with excess Boron, Chromium and Copper. They said “Raised levels of these elements within the steel can lead to problems of cracking of welds, [and it] could take as long as 48 hours to develop cracks in the welds of affected structures. A similar problem can arise with copper-alloyed steel. Again, Chinese imports have been discovered with elevated levels of copper.”

Ian Rodgers, Director of UK Steel, warned:

“It is imperative that structural steel plates and sections with elevated alloy levels are treated with great care and where possible avoided totally for applications where welding is required, as there is a heightened risk of catastrophic failure. Our advice is that customers should carefully check the alloy content of Chinese structural steel before processing it.

“This is a time consuming process however as the only way of telling which Chinese rebar contains Boron would be to test each bar. Otherwise, fabricators cannot tell which welding technique to use. But such tests are not generally undertaken. There is thus a real, but unquantifiable, risk that welded structures using Chinese rebar could fail.”

The Welding Institute has issued advice about adapting welding techniques for steel containing high levels of Boron:

“For rebar identified as having Boron content in excess of five parts per million, additional precautions during welding are advised. These include, but are not limited to, slower welding, higher heat input and additional controls on consumable hydrogen levels. It is advised that a specific weld procedure is developed and used for these higher Boron materials, incorporating all the precautions usually undertaken to avoid delayed cracking (dry material, not stored outside, controls on consumables etc.), and additional measures applied to account for the elevated Boron content, or the diameter of the bar.”

The Galvanizers Association is also advising members to be aware of this issue and to contact their offices should you have any concerns regarding the quality of the steelwork presented to you for processing.