Document npKG4wgbojXO77KRNZqoLe0kG

PRACTICAL IDEAS ...here's the trading pest for year operating and maintenance short cuts _ snvc flONtGA, Amdole Editor of insulating cement and a coat af fi. ishing cement. Standard 12x36-in. block sections cut to fit three sides of sheet-meul enclosure over damper and eipas^ joint. While mineral-wool blocks ire also secured with bands on veriiea)^. closure surface, smaller insulation see- lions on enclosure aides are held |n place by wire mesh. Enclosure Insult- lion is finished same as regular duet surfaces. Photo shows Insulating blocks cut around the damper-control lever <m the left side of the duct. H W Smith NewYork, N. Y. Mussels Die Yeung Now Preheating eastings to right tempera* luro before welding on a hard overlay makes difference between success and failure. This photo shows fast, acourate tem perature Indicator with attachment (or this purpose. Just place hand pyro meter's thermocouple tip on heated cast ing, and one quick gtanco at instrument tells welder when to start laying on the expensivo electrode for best results. H Mali* Schenectady, N. Y. Insulate Duct Expansion-Joint, Damper as Unit W* aemtcRO both installation time ond materials cost in duct insulation by lo cating expansion joints and dampers side by side. Then we covered both as a unit Sketch shows adjacent V-typc expansion joints and damper flanges In eirculor air ducts covered in this men.ner. Single sheet-metal enclosure and banded mineral-wool block insulation does job. Photo shows damper ond expansion joint, located on one of three vertical ducts at intersections. They receive pre heated air at about 620 F. Hot air is then delivered down through fans to pul verisers. Surfaces of both vertical and overhead duets are insulated with one layer of S-in.-lhick mineral-wool blocks in 12x36-in. sections. Blocks are se cured to the ducts with 94-in. bands on about 9-in. centers, covered with wire mesh, and finished with e %-in. layer At Loa Anccles, horbor water U brought in through duplicate conduits, either o! which can carry almost entire cooling-water load, while other it emptied when mechanical cleaning U needed. Station has operated since 1943. Un til 1946, there was no conduit-fouling problem. Petroleum and manufacturing industries emptied high sulfides into the harbor waters. Sulfides killed miriee life and corroded the aluminum-brass condenser tubes. In 1946, harbor pollution was r dueed. There was less hydrogen sulfide concentration. As oxygen in the waters increased, marine life began to thrive. Conduits, pumps and suction sirsiners clogged. Among offenders were bay mussel, a rock-boring clam, barnacles and vegetative matter, end other mariae organisms. II T Duplice read a paper on all this recently at die Los Angeles meeting of A5ME. He told how ho and C Alex ander determined to kill marine life while it was still young. Reason was that shells would be small enough to pass through the entire cooling system to the discharge conduit. A continuous chlorination system was first thought of, but this wss too costly. After testing various possible methods, these men sealed off one circulatingwater conduit at both ends to prevent water passage. This was done for five to seven days every (our weeks during bsy-mussel-spawning period. Mussels consumed oxygen in cloed-ofl water ond died when there was no more. After 6rat teat, when tunnels stop-log was raised, over 45 tons of dead msrios life were washed out of conduit sad into discharge basin- Method has been successful since June 1952. pown130 PUNT OPERATION AND MAINTENANCE SECTION ptUr Copper bonding -strip | |b Steam Condenser Care ' i Idle Condensers: Keep water side ol : condenser either completely filled or i entirely empty. If filled, circulate water 1 often. If empty, dry tubes inside by ' blowing with air lance; drain steam side. \ Water Side: Clean inside of tubes * end waterhoxeo at frequent intervals, ^ depending on deposits like slime, scale, taud, oil, greaso, sea growths. For xsnal cleaning, flush waterboxes with warm fresh water; wirebrush lightly. - Clean tubea with air or water lance, wire-brush, or blow tube plugs through. Flogs are rubber, metal, rubber and 'einvaa, or inetal and canvas. When cleaning tubes and waterboxea, . tlean and examine tine plates. Renew oecs if more than half deteriorated. When reinstalling xlnc, make good me tallic contact to condenser. Corrosion: Wasting sway or thinning down of tube. Tube inside Is evenly wrroded without formation of pita or :|dttincificd spots. Cure here is to in* ` Ull tubes of cupro-nicke) alloy. Cause ' b acid in circulating medium. Detind/ieotien: Zinc is taken out of tube, leaving a spongy and brittle cop* per behind. It takes place irregularly, Sects tube only io spots. Counteract by installing sine plates in waterboxes. Water flow through condenser acts as k electrolyte for fior of current between doc plates and lubes. Deposit Attack or Pitting: Small, wind pits or pinholes beneath green ult and euprite. Foreign deposits often ecompsny this type of corrosion. Low ' circulating-water velocity end stray electric currents intensify this corrosion. Binding copper wire around wolerbox Old Auto Brake Opens Window, Holds in Place Plakt windows often open on a hinge at frame center as shown in photo. Windows are controlled and set with fist steel bar, fastened to bottom end notched so edge engages stationery member at till bottom. Trouble is a slight jer that ean upset bar closet win dow with sudden bang. Or notches in bar may be spaced so you can't get the right ventilation without tho drafts. To solve our problems, engineers of Park St Bridge, Alameda, Calif, in- 'stalled an eld automobile hand brake for the desired controls in operating lower. Now each notch on pawl opens window about one inch, holds it easily without danger of accidental tripping. C Burnley Alameda, Cali}. flange bolls and grounding to earth usually nullifies stray electric current*. Taiied-Type Pitting: Pits formed by scale removal have deep seeiion st up stream side and shallow trail at down stream side. Condition is front water flow through tubes. Only way to com bat is to keep water flow as slow as pos sible. Keep xino plates in condition. Tube Erosion: Tube is worn away by action of solids in oirculating water, often accompanied by corrosion. Low circulating-water velocity keeps this at tack to a minimum. /npiitfenteni Attack: Corrosion caused by air bubbles, and generally confined to tube's Inlet end. This is uni form thinning or appears at grooving. Control circulating water so a slight discharge of water from wolerbox vents mlnlmltes this attack. Scale Thinning: Scale kept thin by chemical action, resulting in corrosion and isolated pits. Zine plates, causing scale formation through galvanic action, ore effective here. Solution: Scale absence due to pres- once of acids, etc, resulting In general thinning. Proper care o( sine plates will minimise this attack. Splitting, Season Cracking: Split tins in a longitudinal plane. This is from improper annealing of tubes during making. Reject or roploco such tubea. Graphite Corrosion: Salt-water action on cast iron, in which cast iron becomes very soft and spongy. Best protection is to paint wolerbox with coaling of as phalt or cement paint. Paint acta as an insulator between -waterbos and water. Electrolysis: Ceased by electrical ac tion in tubea. Minimised by bonding all metal together, grounding to earth. A D Collin Washington, D. C. Watch These Leads When tou put-your ohrameter on tho shelf, pul] out the leads or turn tho selector switch to Orr or some ether position then Ohms. Then, if ihe-leada accidentally become shorted, the bat tery will not be discharged. Eo Eockrt New York. N. Y.. (Continued on page 132) - fcCEMSER 1933 RIANT OPERATION AND MAINTENANCE SECTION