New Zealand Engineering 1999 June

IPENZ News

IPENZ Environmental Award 1999
Crest Award for IPENZ member
Change to Galvanizing Standards
April 1999 additions to and changes in the classes of membership

IPENZ Environmental Award 1999

IPENZ president, Sir Ron Carter, recently presented a commemorative bronze plaque to Don Walker of Clearwater Wellington, the winner of the IPENZ Environmental Award for 1999.

The presentation took place, on site, at the Moa Point Treatment Plant. Representatives from IPENZ, Clearwater Wellington (Anglian Water International, Wellington City Council, Opus International Consultants, and Mainzeal Property and Construction) were present.

The IPENZ Environmental Award, established in 1971, recognises engineering work in which care and consideration of environmental values are an outstanding feature of the design.

Crest Award for IPENZ Member

Julian Reweti, IPENZ Wanganui branch, accepted the CREST Industry Award at the CREST ‘Invent Event’, but the award was earned by the membership of IPENZ, Wanganui.

CREST (Creativity in Science & Technology) is a national awards programme for Year 7-13 students which encourages them to take on real-life projects with support from people in industry and the community.

IPENZ engineers, Tony Gordon, Rob Timpany and Julian Reweti, have acted as consultants and assessors for students’ CREST projects in Wanganui secondary school for 10 years.

Julian, civil engineer and manager of Water Services, Wanganui District Council, laughed as he reflected back over some of the projects in which the engineers have been involved. "Some of them don’t have much to do with engineering. However, the students make their own choices and that’s an important aspect of the CREST project they do." While the projects don’t necessarily require the professional expert knowledge of engineers they do require creative, highly flexible consultants and assessors.

They also illustrate the Technology Curriculum particularly well. In 1998 for example Rochelle Harden decided she’d try to make a toilet roll inner that could be conveniently flushed away. Rochelle tried soaking several types of paper in various stiffening agents such as gelatine, cornflour, starch and sugar in various proportions. None worked well; it was sheer inspiration that led her to try hairspray. It worked! The hairspray treatment produced a remarkably effective flushable toilet roll inner. Engineer Michael Darnell of Opus International Consultants Ltd, called in to assess Rochelle’s efforts, had little difficulty in this case. Rochelle had demonstrated the creativity and perseverance required by the CREST Silver Award criteria and had made good use of consultants.

Change to Galvanizing Standards

Two well-known standards for galvanizing have been withdrawn as they have now been replaced by new standards.

BS 729:1971 has been replaced by BS EN ISO 1461:1999 ‘Hot dip galvanized coatings on fabricated iron and steel articles. Specifications and test methods’ This is inapplicable to sheet or wire galvanized by continuous hot dipping, and to tube and pipe hot dip galvanized in automatic plants.

Similarly and of more relevance in our part of the world, NZ/AS 1650-1989 ‘Hot-dipped galvanized coatings on ferrous articles’ has been replaced by the following three new standards.

AS/NZS 4680:1999 ‘Hot-dip galvanized (zinc) coatings on fabricated ferrous articles’. Thiscovers structural and reinforcing steel, fabricated wire and tubes, castings and nails that are galvanized using the conventional batch process, with or without centrifuging, and closely matches the ISO 1461 Standard. Coating thickness is determined by the thickness of the article and is now specified in microns instead of g/m² (eg. sections >6 mm are required to have a minimum average coating thickness of 85 microns (�m) and a local minimum of 70 �m which is equivalent to an average of 600 g/m² of zinc).

AS/NZS 4791:1999 ‘Hot-dip galvanized (zinc) coatings on ferrous open sections, applied by an in-line process’ covers manufactured products such as cold-formed purlins. These are designated by the letters ILG (in-line galvanized) and a two or three digit number representing the specified minimum average zinc coating mass in g/m² on each side (eg. ILG150 has an minimum average thickness of 21 µm. This section would previously have been designated as Z300 which was based on the total weight of coating in g/m² on both sides of the sheet).

AS/NZS 4792:1999 ‘Hot-dip galvanized (zinc) coatings on ferrous hollow sections, applied by a continuous or specialised process’ covers three different manufactured products as follows;

a) Hollow sections coated on both surfaces. RHS with a coating thickness of 300 g/m² (42 µm) would be designated HDG300.

b) Hollow sections produced by welding pre-galvanized strip. A section made from Z275 sheet would be designated ZB135/135. These sections may have a different thickness between external and internal surfaces

c) Hollow sections coated on the external surface only. A tube with an external coating of 100 g/m² would be designated as ILG100.

Notes:

1. Continuously galvanized coatings are different to those formed in the traditional hot-dip galvanizing process. Batch dipped items have a longer time in contact with molten zinc, typically from 2 to 8 minutes. This results in a coating which is less ductile, but is thicker and more abrasion resistant (due to the formation of a thicker iron/zinc alloy layer that is harder than the base steel). Care is therefore required in specifying product for external use, especially in marine or other aggressive environments where the in-line/continuously galvanized coating will require additional protection to give durability.

2. Galvanized wire and welded wire fabric is covered by AS/NZS 4534:1998 ‘Zinc and zinc/aluminium-alloy coatings on steel wire’, and galvanized sheet by AS 1397-1993.

W L Mandeno, Opus International Consultants Ltd. IPENZ representative on the MT/9/8 standards joint technical committee.