BIC Magazine November 2015 : Page 68

INSIDE INDUSTRY By: DOUG WRIGHT, Director of Research and Development, Engineering StoneAge Inc. Refractory removal by high-pressure waterjet T he removal of refractory from lines and vessels in the petrochemical industry is necessary for inspection, repair, maintenance and replacement. Refractory materials are installed in vessels, boilers and process lines to provide insulation and erosion resistance. The primary components are alumina and silica, and the lining may be cast in place, gunned or manually applied. Small spaces and difficulty of access have otherwise lim-ited methods of removal to manual labor with handheld chipping hammers. Refractory materials can be safely removed through the proper application of high-pressure waterjets and mechanization, from localized repairs to complete clean-ing. Moreover, the removal of refractory by high-pressure waterjet has been proven to be more than 10 times faster than manual chipping, resulting in the elimination of over 500 hours of worker exposure to silica dust, noise and vibration within a confined space on a typical refractory replacement. The application of water for the sup-pression of silica is a well-known control, dating to the early use of pneumatic rock drills in underground mining. These drill-ing operations were performed dry, with operators breathing the dust produced. This resulted in an average life expectancy of four years for the miners due to silicosis, leading to the “widow maker” name for these first drills. The addition of water through the drill steel to the bit completely eliminated the dust and saved many lives going forward. A demonstration of manual chipping with a 15-pound pneumatic hammer was conducted in Type 1 refractory, 5-inch thickness, installed within a 40-inch diam-eter section. The operator of the hammer worked for one hour within a 12-inch square. The result was an estimated remov-al rate of 0.1 cubic feet per hour, illustrated in Figure 1. Figure 2 shows the effect of one hour with high-pressure water, operating at 18,000 psi and 73 gallons per minute, resulting in a removal rate of 9.5 cubic feet per hour. The waterjet removal rate was 100 times faster than manual chipping in this application. Operating pressure and flow rate are dependent on the refractory type and thick-ness, the expected standoff distance from the surface that can be achieved, the rate of production desired and the type of equip-ment to be used. As with most other mate-rials, the most efficient pressure is around two to three times the minimum effective pressure. The complex geometry of some internal structures may require a support system for the waterjet tooling to maintain effective standoff distances. High-pressure waterjetting, when prop-erly applied, has proven to be an effective method of removing refractory. The use of high-pressure water allows the transmission of hundreds of times the power of handheld chippers, with resulting refractory removal rates on the order of days to weeks faster, while removing these workers from expo-sure to the hazards of silica dust, extreme noise, vibration and physically exhausting labor in a confined space. For more detailed information, test results and estimations of remov-al rates, download the complete white paper at www.stoneagetools. com/engineering-papers or call (866) 795-1586. Figure 1. Results of manual chipping in Type 1 refractory, one-hour duration. • Figure 2. Results of waterjet removal in Type 1 refractory, one-hour duration. Replacement Trays/Tower Internals Sieve, Round & Rectangular Valve, Bubble Cap Trays Support Rings, Beams, Weld-ins Packing Support & Hold Downs Separation Equipment Mist Eliminators, Chevron Vanes, Coalescers Stop throwing your money down the tubes. Why replace the entire tube when only the fi rst few inches need repair? CTI Shield/Seals™ — Thin-walled tube inserts made of highly durable alloys Eliminate the need to replace heat exchanger tubes Precisely sized to fi t damaged tube ends • Expanded mechanically / hydraulically in-situ into parent tubes • • All Packing Types Random (Rings), Structured, Grid Type Air coolers, steam condensers, feedwater heaters, waste heat boilers and more • Over 6 million installed worldwide • What if the whole tube is damaged? HARDWARE & TOWER INTERNALS Our customers are #1 1424 Sens Rd -Suite 4 -La Porte, TX 77571 281-867-9325 | sales@responsesupply.com www.responsesupply.com COMPETITION IS GOOD…GO GREEN! CTI’s Full-Length Tube Liners™ — A cost effective and time saving solution for extending the life of new or damaged air coolers and heat exchangers while avoiding costly component replacement. Leaking heat exchanger tubes that have been plugged can be restored to service! Save money and increase reliability. (203) 795-0070 • (800) 446-0060 www.cti-ind.com • ctius@cti-ind.com 68 November 2015 Read BIC Magazine online at BICMagazine.com

Refractory Removal By High-Pressure Waterjet

Doug Wright

The removal of refractory from lines and vessels in the petrochemical industry is necessary for inspection, repair, maintenance and replacement. Refractory materials are installed in vessels, boilers and process lines to provide insulation and erosion resistance. The primary components are alumina and silica, and the lining may be cast in place, gunned or manually applied. Small spaces and difficulty of access have otherwise limited methods of removal to manual labor with handheld chipping hammers.

Refractory materials can be safely removed through the proper application of high-pressure waterjets and mechanization, from localized repairs to complete cleaning. Moreover, the removal of refractory by high-pressure waterjet has been proven to be more than 10 times faster than manual chipping, resulting in the elimination of over 500 hours of worker exposure to silica dust, noise and vibration within a confined space on a typical refractory replacement.

The application of water for the suppression of silica is a well-known control, dating to the early use of pneumatic rock drills in underground mining. These drilling operations were performed dry, with operators breathing the dust produced. This resulted in an average life expectancy of four years for the miners due to silicosis, leading to the “widow maker” name for these first drills. The addition of water through the drill steel to the bit completely eliminated the dust and saved many lives going forward.

A demonstration of manual chipping with a 15-pound pneumatic hammer was conducted in Type 1 refractory, 5-inch thickness, installed within a 40-inch diameter section. The operator of the hammer worked for one hour within a 12-inch square. The result was an estimated removal rate of 0.1 cubic feet per hour, illustrated in Figure 1.

Figure 2 shows the effect of one hour with high-pressure water, operating at 18,000 psi and 73 gallons per minute, resulting in a removal rate of 9.5 cubic feet per hour. The waterjet removal rate was 100 times faster than manual chipping in this application.

Operating pressure and flow rate are dependent on the refractory type and thickness, the expected standoff distance from the surface that can be achieved, the rate of production desired and the type of equipment to be used. As with most other materials, the most efficient pressure is around two to three times the minimum effective pressure. The complex geometry of some internal structures may require a support system for the waterjet tooling to maintain effective standoff distances.

High-pressure waterjetting, when properly applied, has proven to be an effective method of removing refractory. The use of high-pressure water allows the transmission of hundreds of times the power of handheld chippers, with resulting refractory removal rates on the order of days to weeks faster, while removing these workers from exposure to the hazards of silica dust, extreme noise, vibration and physically exhausting labor in a confined space.

For more detailed information, test results and estimations of removal rates, download the complete white paper at www.stoneagetools. com/engineering-papers or call (866) 795-1586.

Read the full article at http://trendmag.trendoffset.com/article/Refractory+Removal+By+High-Pressure+Waterjet/2303268/277555/article.html.

Response Supply Inc.

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