Middleton Firm Has Big Steel Bridging Contract

Press, Volume XCV, Issue 28223, 11 March 1957, Page 14

Middleton Firm Has Big Steel Bridging Contract

The largest steel bridge con-1 struction contract ever let in New Zealand is being carried out for the Ministry of Works at the Middleton factory of C. W. F. Hamilton and Company. Ltd. To offset the lag in its bridging programme, the Ministry has I adopted a standard form of steel girders. The Christchurch firm and another firm in Auckland are between them fabricating 2806! tons of steel. The girders will be stockpiled and. when piers are ready at the 1 , bridge sites, will be transported) to them and placed in position. All that will have to be done; after will be the pouring of the; decks. The quantity of steel being fabricated at Middleton under] the contract is 1840 tons, which, suggests that the South Island and the southern end of the: North Island have pressing needs) for bridging to be met. The; steel will provide one mile oi bridging. The whole area of more than one acre of factory site could be carpeted with the stock of j-inch steel imported, from England. On Thursday, the steelwork for tlie first bridge left Middleton. It was railed to the Invercargill district. As bridges are finished, the steel will be transported to the stockpile of the Ministry of Works’s yard in Blenheim road. Under the standardisation programme. Hamilton and Company is making girders of varying lengths. They are: five with 60fl spans. 13 with 70ft. 32 of 80ft. three of 90ft and 13 of 100 ft. Girders Interchangeable The girders are interchangeable so that when bridges have to be constructed of different lengths the Ministry can draw the spans from stock and fit them up. So that they can be easily transported. the 100 ft spans are broken into three sections—two of 30ft and one of 40ft —with splice places between the sections. The heaviest girder weighs 10 tons, the heaviest section being four tons. But no girder has to be handled in one piece uutil it is on the bridge site.

Sixty thousand high tensile bolts and 100.000 specially hardened washers will be used in the assembly of the bridges. After fabrication, all the steel is shot-blasted and painted with a rich zinc paint to form a cold galvanising. The blasting plant is a new one of English make and delivers 200 cubic feet of air a minute. * Hopes for Speeding Up Every day, an 80ft span is being built. The company hopes that the production will speed up as the technicians get into the swing of the job. The making of components began last August but the main steel supplies did not arrive till Christmas, and the main work was begun at the end of February. The expectation is that all the steel will be fabricated by early in 1958; as technique improves, the end of

1 this year may be a closer target ! date. The steel is being automatically welded at the rate of two and a half feet a minute. A great saving In time has been obtained at Middleton by I the development and setting up I of the first multi-head gas cutter to operate in New Zealand. The cutter operates up to six heads, cutting through 40ft of one-inch plate every hour: a similar cut by a hand cutter takes four to five hours. The biggest plates to be cut measure 40ft by sft 6|m and have to be cut into four plates each 16in wide. The imported plate is set up on the table, lined up. and the cutting into four parts is done in the | one run.