standards, safety and the emerging impacts of...

STANDARDS, SAFETY AND THE EMERGING IMPACTS OF GLOBALISATION

Arun Syam, Anthony NgOneSteel

Friday 25th November, 2016

• Introduction• Situation 1: Boron additions in Carbon Steels• Situation 2: Brittle Fracture• Recommendations• Conclusions

Outline

• Globalisation in construction (and other industries)• Safeguards in Australian Standards and Building Codes• Standards’ revisions to reduce arduous work for structural reliability

Heads up/trends


Introduction

• National Construction Code (NCC) and deemed-to-satisfy solutions• AS 4100 and “cascading” (or secondary) Standards for structural steel• Standards set a minimum benchmark & provide an acceptable minimum

level of safety• However, failures still occur when Standards are complied with• Standards need to be adequately maintained – globalisation has not helped

the situation• Two case studies are considered:

i. Addition of the chemical element Boron (B) to structural steelsii. Brittle fracture provisions in AS 4100 Steel Structures


Boron additions in carbon steels


• The addition of Boron to carbon structural steels into Australia was first identified in about 2013

• Anti-Dumping Commission, Final Report No.291, Anti-Circumvention Inquiry, Hollow Structural Sections Exported from the P.R.of China, Republic of Korea, Malaysia & Taiwan (Doc 037), Australian Government, 29 Feb 2016

• The report found that Boron in amounts of 8ppm was deliberately added to Hollow Structural Sections (HSS) so that the steel could be reclassified as alloyed HSS to bypass trade measures and to be marketed as compliant with AS/NZS 1163

• Uncontrolled levels of Boron in steels produce safety concerns – specifically with the weldability of steels as Fabricators could presume the steels are pre-qualified to the Welding Standard (AS/NZS 1554 Parts 1, 5 & 7)

• The addition of Boron (in this instance) did not manifestly provide any metallurgical or marketing benefit.


• Concerns on this situation were echoed on various fronts:

QLD T&MR WTIA ASI WTIA WTIAATM HERA (NZ)

Advice was provided such as:• all steel material test certificates should list boron content,• if boron is not listed it must then be tested for its presence• if boron contents are above 8ppm then weld procedure requalification is

requiredSTANDARDS, SAFETY AND THE EMERGING IMPACTS OF GLOBALISATION

A communique issued by the Thai Industrial Standards Institute on 20 September 2016 notes that:Thailand enforces new standard for structural sections. Thailand continues to progress its review of construction steel products in order to ensure that mandatory standards for mechanical properties and chemical composition are met. A new, widely-awaited Thai Industrial Standards Institute (TISI) standard for hot rolled sections will be enforced 180 days after September 16, TISI sources confirmed. This follows a notification the same day in the Thai Royal Gazette.The standard will apply to HR structural sections including angles, channels, I-beams and H-beams. As previously reported, TISI announced in January this year that it was planning to introduce TISI 1227-2558 which stipulates the maximum permissible levels of the following elements: 0.4% copper, 0.3% chromium, 0.08% molybdenum, 0.05% titanium, 0.0008% boron and 0.3% nickel.

Additionally, it is stated that:Alloy-added steel is not supposed to be used in construction. There could be risks involved," a Bangkok steel source said. These alloy-added products are imported under the same codes as alloy steel but are resold in the Thai mild-carbon steel market, he said.


• For various reasons there has been little research available on the effects of Boron on carbon steels, though there have been numerous concerns in some tests and other references noting significant issues in this area

• What is known is that finished alloy steels which have been heat treated (egquench & tempered plate to AS 3597) to activate the beneficial properties (hardenability) offered by Boron, have to be welded to a different part of the welding Standard (ie AS/NZS 1554 Part 4)

• Standards Committees involved in writing product & welding Standards (egAS/NZS 1163:2009 and AS/NZS 1554 Parts 1, 5 & 7) basically had not considered significant (and uncontrolled) Boron additions to carbon steels


Types of steels referred to in the (Australian) product & welding Standards

AS/NZS 1163, AS/NZS 3678, AS/NZS 3679.1, AS/NZS 3679.2 as well as AS/NZS 1554 Parts 1, 5 & 7 have the following Carbon Equivalent (CE) formula (based on the International Institute of Welding (IIW) formula):

It can be rationally argued that unless limits are placed on Boron and/or mandatory statements that Boron shall not be intentionally added, then the current (IIW) CE formula needs to allow for Boron.

“It was obvious to many of us, who understood the boron effect, that the Lloyds (i.e. IIW) CE formula would have to be significantly modified but even after the availability of comprehensive research data certain parties were reluctant to accept the facts. Eventually, as a compromise, the following wording was incorporated in to the relevant standards where it remains largely unaltered to this day. Thus in Annex C of BS EN 1011-2: 2011 at the end of paragraph C2 under the Lloyds CE formula we find the words:

“This carbon equivalent formula may not be suitable for boron containing steels” (Kirkwood, 2014)

Where’s Boron?


The Welding Institute (TWI-UK) FAQ - What is the difference between the various Carbon Equivalent Formulae used in relation to hydrogen cracking?

Various Carbon Equivalent (CE)

formulae developed depending on

chemistry, application and time

period

Used in AS/NZS 1163/3678/3679 AND AS/NZS 1554 Parts 1, 5 & 7 on the basis that Boron was NOT present

Preferred by Cottrell & TWI due to being able to cover a wider range of chemical compositions and welding conditions + improved cracking predictability

Boron’s artificial economic benefit?• A rapidly globalised economy has resulted in perverse outcomes due to a

combination of trade measures (circumvention and countervailing)• How should Australian procurers and fabricators handle this?• Need to understand the relevant Australian structural steel welding

Standards – specifically AS/NZS 1554 Parts 1, 5 & 7 and its concept of pre-qualified welding procedures for each joint preparation: ie welding process,

consumable type, edge preparation, welder qualification, heat input and (indeed) parent material

• These weld pre-qualification tests were done basically on non-Boron bearing steels (AWRA 1960s)

• Consequently, a comprehensive study is required in this area of relatively large and uncontrolled levels of Boron in welding structural steels


• If not done so, the welding Standards should preclude the significant (and uncontrolled) levels of Boron in structural (carbon) steels as being pre-qualified steels to AS/NZS 1554 Parts 1, 5 and 7

• Possible options include:(a) undertake a significant research program to include Boron-bearing

steels(b) exclude Boron from the relevant product & welding Standards(c) remove AS/NZS 1163 from the material list of pre-qualified materials in

the relevant welding Standards• Need to keep to status quo on safety, hence

– (a) is optimal– (b) is pragmatic, and – (c) is least preferred for many reasons


• The 2016 versions of AS/NZS 1163, 3678, 3679.1 & 3679.2 have left it to the specifier, purchaser, asset owner etc to address this issue on weldability

• Two Standards Australia (SA) Technical Specifications (TS) were released on 5 April 2016:

SA TS 103:2016

Standards AustraliaTechnical Specification

Structural steel welding –Limits on boron in parent materials

SA TS 102:2016

Standards AustraliaTechnical Specification

Structural steel – Limits on elements added

Brittle fracture and AS 4100


Brittle fracture

• Steel designers need to consider brittle fracture for various reasons including low fracture toughness of the steel at the service temperature or a service temperature below the transition temperature of the steel.

• The principal method is the selection of a steel that will operate in the notch-ductile temperature range

• For a particular steel product, differences in various material characteristics arise from the steel making process and chemical composition – even though they may comply with the same or similar product Standard

• Gardiner, S., Clifton, G.C. and MacRae, G.A., Performance, damage assessment and repair of a multi-storey eccentrically braced framed building following the Christchurch earthquake series, SESOC NZ Conference 2-3 Christchurch, November 2012. Ref [32].


LODMAT ISOTHERMS


AS 4100 Steel structures: First published in 1990 Work commenced on this in mid-1980’s well before

imported steels were prevalent in Australia Relates to test data and material characteristics in

Australian-made steels at that time Specifically Table 10.4.1 of AS 4100 “Permissible Service

Temperatures According to Steel Type and Thickness” which is based on material statistical data at that time for various steel types

The values in the Table accurately reflect the notch toughness properties of steels produced by Australian manufacturers it does necessarily reflect other products manufactured to an overseas Standard or even if it is manufactured overseas to an Australian product Standard.

Due to increased global trade, the consequent assumption by designers that this is applicable to any Standard’s steels will potentially lead to unsafe designs.


How Australian Standards should address this issue

• The background to this issue indicates that design for brittle fracture is reliant on the material properties of steels referenced in AS 4100 rather than those in the material Standards (eg AS/NZS 3679.1, etc)

• There are two options available:(1) Remove Table 10.4.1 and require designers to use the impact grade

appropriate to the design temperatures without variation for varying thickness of material

(2) Provide additional requirements in the material Standards (such as AS/NZS 3679.1 etc) to ensure that the requirements of AS 4100 Table 10.4.1 are met.

• Option (2) is preferred as it maintains the level of safety required by the NCC whereas Option 1 is likely to increase steelwork costs.


Recommendations – Boron additions in carbon steels• Require Standards Australia to limit Boron levels in the relevant structural steel material

and welding Standards• In the interim, use the recently published complementary Standards Australia Technical

Specifications in conjunction with steelwork specifications – i.e.

Structural steel welding to comply with AS/NZS 1554 Parts 1, 5 or 7 [strike out whichever part is not relevant] and Standards Australia Technical Specification SA TS 103.

Similar wording can be used when referencing the structural steel material Standards.

Recommendations – AS 4100 and Brittle fracture • Require Standards Australia to provide additional requirements in the relevant structural

steel material Standards• If imported material is supplied then verification testing by a NATA registered Laboratory

is recommended for each identified batch of material supplied in accordance with the type testing requirements for impact properties of the relevant Australian materials Standard.

Conclusion• This paper considers some negative aspects of globalisation and structural engineering

Standards• Two situations were highlighted• The drivers, updates and interim solutions were provided• A significant take out from this is that Standards cannot be simply amended (or not be

maintained) with a changing world supply and consequent change in material conditions• An appreciation of the links a specific Australian Standard (e.g. AS 4100) has with other

related (“cascading”) Australian Standards is required with clear explanations provided for incorporating change.

Thank you


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