Metals company explosion blamed on reading of sensor

The Associated Press 10/01/99 12:47 PM Eastern

ALBANY, Ore. (AP) -- A Sept. 7 explosion that injured five employees at the Ormet-Wah Chang metals plant has been traced to a sensor that employees thought was sending a false signal.

Jim Denham, a spokesman for the metals company, said the computer control system sounded a warning to employees about three hours before the blasts as they tried to fire up a furnace.

The signal meant a water jacket surrounding a copper crucible in which titanium was melted lacked sufficient flows to cool the crucible.

Denham said adequate water flow is critical because copper has a lower melting point than titanium.

He said employees checked and found water in the jacket but did not realize the outlet valve to the cooling system was closed so the water could not cool the heat.

Employees adjusted the water flow sensor until the low-flow alarm was cleared, he said. The furnace eventually overheated, softening the copper and breaching the containment jacket.

When the water came in contact with the molten titanium it broke down into hydrogen and oxygen, Denham said.

A steam explosion was likely followed by exploding hydrogen, he said.

Four workers who suffered minor injuries are back on the job. William Edwards, 37, of Lebanon, has been released from the burn unit of Legacy Emanuel Hospital in Portland and is recuperating at home. He had second-degree burns to his back, arm, abdomen and face. He is expected to return to work.

Denham said the plant is operating at about 80 percent capacity.

Questions? Comments? Suggestions? We welcome your feedback.

)1999 Oregon Live LLC

http://flash.oregonlive.com/cgi-bin/or_nview.pl?/home1/wire/AP/Stream-Parsed/OREGON_NEWS/o0347_PM_OR--OrmetBlast

-- Homer Beanfang (Bats@inbellfry.com), October 01, 1999

Answers

Employees adjusted the water flow sensor until the low-flow alarm was cleared, he said. The furnace eventually overheated, softening the copper and breaching the containment jacket.

A MAGNIFICENT example of 'fix on failure' and the results!!!

-- Billy-Boy (Rakkasn@Yahoo.com), October 01, 1999.

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This accident is a good example of how a fix on failure method, when used in a dangerous working environment, can be fatal.

See my post below, titled: "Fix On Failure Probably Won't Work"

http://greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=001VHY

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-- no talking please (breadlines@soupkitchen.gov), October 01, 1999.

The explanation is not consistant with common methods.

If the water return valve was closed, the furnace would be protected with a high limit switch in addition to a flow alarm and a flow switch.

This story is no more believable than the Mars probe story. At least I have some first hand experience with boilers and this is fiction that doesn't pass the smell test, IMO.

I could be wrong.

-- Tom Beckner (tbeckner@xout.erols.com), October 01, 1999.