Building production capacity at Russia's largest steel and steel-related mining companies doesn’t happen without planning, staging, careful product selection and execution. PAO Severstal announced their plans to add a third blast furnace to the company’s Cherepovets Steel Mill in the Vologda Region, Russia. Corresponding with the install was construction of a wet cleaning scrubber and demister.
Construction planning in most manufacturing settings includes work performed by engineers, pipefitters, welders, electricians, blasters and painters. Their ability to work simultaneously and nearby each other was vital to meet the firm deadlines. Effectively staging abrasive blasting with only 20-days to work, was critical to project success.
The project called for fabricated and welded steel to be blasted to ISO 8501-1 Sa 2.5 cleanliness level, at a minimum ±75μm(±3mil) profile. Most of the blasting and painting was in the scrubber, but also included the demister. The scrubber measured 30m(98ft) tall and 6m(19ft) wide. Exit and entry into the scrubber was through a number of narrow manways. Total blasted area of both sections was 940m² (10,200 ft²).
Facility personnel considered two abrasive types - copper slag and Sponge Media. Of special interest to management were aspects that would compliment the overall construction plan. Among the decision points were...
- Achieving the specification and doing it quickly.... copper slag as tested was unable to meet profile requirements (producing a ±50μm(±2mil); Sponge-Jet blasting with Silver 16 Sponge Media™ could satisfy both the profile and required cleanliness.
- Trades working concurrently to nearby active blasters... Sponge Media (with built-in dust and rebound suppression) is more easily contained, and as a result would provide an edge over copper slag with less likelihood of disturbing nearby trades and installers.
- Efficient media collection and handling (reduced complexity of blasting)... for the same volume, the weight of copper slag is four times more than Sponge Media - 1600kg/mᶟ(100lb/ftᶟ) versus (432kg/mᶟ(27lb/ftᶟ) respectively. Heavier copper slag presented collection and removal challenges after blasting. If slag was used, it would fall to the scrubber floor, be collected, and then transported via one manway. Falling copper slag would create safty hazards for the tradesmen working below.
For lighter Sponge Media, scaffolding sections could become collection floors. Each floor with a manway would use a construction funnel leading from the scrubber outside and down to a media recycling area. From recycling areas, media would be fed back into the pressure vessel for blasting.
The final choice to use Silver 16 Sponge Media was made because it could quickly achieve the specification while controlling abrasive blasting operations. “Its value to facility personnel was how easily abrasive blasting and painting could fit into the larger plan,” offered the Sponge-Jet Distributor PASSATSTAL RUS, Ltd who was onsite.
By day twenty, blasters and painters were finished. A contributing factor was that painting could be done just meters from the blasters. “Management was impressed," said Timofei Timofeev, Director, PASSATSTAL RUS, Ltd. He continued, "the top portion of the scrubber was able to be coated at the same time while the bottom portion was blasted with Sponge-Jet.”
Abrasive consumption was 25 times less than copper slag; efficient media collection and recycling lead to use of less than two tons of Silver 16 Sponge Media compared to the estimated 50 tons of copper slag. Average production was comparable to ordinary blasting at 8m²(86ft²) per hour.