Document KRjOwZp5eo2br6ndGbExbLoBX

More PLANT PROBLEMS. Anolltei Answtr to Jan Question, "How Can We Convert Our Heating Plant r Pr* ornj types3 i-" /gravity ntum from trap vtrtf la otmotpbtf* " -'-1 Still `------ Men y vacuum rttum from trap ASSUMING several conditions, I can give reasonable answers to LW' quesIlona. But before making changes, he may ovoid expensive headaches by con* suiting his local boiler inspector. He map bo o oily, state or insuranee-company man. LW does not say why his boilers mutt run at IS pti. If he Is converting for operoling convenience or economy and his controls are suitable for the lower preaaure, original safety-valve capacity is sufficient. If pressure rises above the control setting, safeties will relieve at their present setting without harm. If pressure is reduced because of boiler's condition, he mutt chonge safety-valve capacity and pop preaaure. Remember, steam at 125 psig bos a specific volume of 3.2 eu ft per lb; at 15 psig (it volume is 13.8 cu ft per lb. This is an increase of sbout 4.3 times. Besides the increased volume, pressure available te force steam through the volve Is less. With a amsller preeture differential, valve capacity Is lest. Steam flow through a safety valve ap* proximate* flow through on orifice. Gy applying roles for orifice flow the lower pressure differential becomes obvious. Also, maximum flow eon be computed. LW has two courses. He can have boilers reclassified as low-pressure units to operate at IS psig. New safety valves will have to be fitted. Or, second, he can keep boilers In their present classificatlon (boiler inspector permitting) end run at 15 psig. Safety valves to relieve at slightly higher than IS psig are advisable. Clessilying the boilers os l*p heating units introduces several economic ad vantages other than fuel savings. Local codes usually permit a reduction in num ber of operators, and there should be a substantiel decrease in insurance premiums. This may be os much as 50%. Cost to convert boilers to run end be classified ns l.p healing units is less than convening for 15-psig operation while remaining power boilers. Coda for Power Boileri applies to any unit operating at a pressure above IS psig. If safety volve is set above this pressure, unit is classified as a power boiler. He can base safety-valve capacity on some pressure above de sired operating pressure. Selling then becomes allowable working pressure. To conform to Code without rceleasl* ficnllon, relieving capocily for stokerfired firetubc boilers must bo at least 7 lb per hr per sq ft heating surfsce. As* turning this boiler has about 1450 sq ft of heating surface and runs at 15 psig with safeties set at 16 psig, output would bo 10,150 lb pe, h, the minimum allowable rci!c ilj, Minimum area of boile, afely-valw connection, bj requirement,, Is 45.0 aq ^ existing 3Win. Mlety ,,|' total opening area ol 19.8 ,, necled to a 3 Win pipe. To lurnieh additional , j ' Code permits InslallaUon ol ain, on the steam lino between bojj. main atop ttal.e axeept wkeo beSi a Buperheater. Aasutnlng steam outlet an boi earnc also aa nonreturn relre, or o additional area can bo pro-lded M aerling o let at boiler outlet end. necting safety to ll. If , Me.' ^ uaed, area obtained Is mars tlun.i quste when area ol two existing ,1 is added to ll. Code requirements be met. If the two existing safeties mj type ordinarily fitted on ftretube bd 1 estimate their capacity as about lb per hr at 125 psig. Theta two can probably be used at 15 psig (f ufacturer changes the springs and vides Increased lift off scat. Napier's equation, eoch valve's should ho at least 2,10 sq fa. to^p! one-third the steam generated, or I* lb per hr. Ask manufacturer H rcqul effective discharge area can be ebt ' New valve must have capacity each of the others. At 16 psig, catalog data show imum capacity of 3%-in. valve U tl 1500 lb per hr. So if existing raj cannot be converted, a new valve; a capacity of 7150 lb per hr is oe , A 6-in. valve on the tee would be able. Computing relieving capacity ece if boilers are reclassified as l*p hesjO units, we find It is 72S0 lb per hr, bsT on Code requirements. Existing tifed could be replaced with two valves ot for heating boilers, each rated 4$$C^j per hr. Though LW may agree with alN t suggestions he should consult boiler V valve manufacturers and the local jj epector before going ahead. I Change of nonreturn valve depenjj on whether boiler Is reclassified. 1*3 is classified a 1-p unit, nonreturn rtT should bo replaced with get# the outeide-screw-and-yoke rlsIni'Wfl die type. I don't think 6-in. valve will operote at the 15-P*'S Tjj sure. See valve monufacturer r* taking valve out of the line. Check pressure-reducing valve to It has sufficient copacity to baniM j| (Continued on page 2*) NANT OPERATION AN0 MAINTENANCE SECTION j*MT 1953 EXTRA MARGIN OF SAFETY The tremendous seal ing power of the Flexitallic Spiral-Wound Gasket is sometimes taken for granted in this age of Jet propulsion and atomic energy. Yet, It is the extra margin of safety built Into each Flexitollic Splrsl-Wound Gasket that has made possible many of the great developments in aviation, atomic research and development, process Industries, power plants, ships of the Navy end merchant marine... Each Flexitallic Gasket (a engineered to meet specific conditions of thermal and physical shock, corrosion, vibration, weaving and unpredictable Joint stresses. Spirally wound V-crlmped plies of required metal with alternating plies of proper filler results In a resilient gasket having characteristics of a calibrated spring. Flexitollic Gaskets are at highest efficiency when bolted up cold ot o predeter mined load. For all preaaure/temperature ranges from vacuum to 4000 lbs., from extreme sub-sero to 2000 F. For all standard Joint assemblies. In four thicknesses for special requirements: .125', .175', .250', .285". With Teflon filler for corrosive chemical conditions. Write us your requirements . .. Flexitallic Gasket Compan/, 8th ft Bailey Streets, Camden 2, New Jersey. Representatives In princlral^des. Consult classified telephone directory. f ANNIVERSARY SPIRAl-WOUND GASKETS ffPB FLANGES, PRESSURE VESSELS AND PROCESS EQUIPMENT ,Mai >11 p]r*l .wound iiiInD or* FUdtoIlle, Loot tor Iho nomo OLEXITALLtC Mompod Into tho mot* ol iptrol o**ry (rnuinr FltillilUt Ootfett. Look for Xlotllo/X* Bio* In (oaboU with oibostoi 81i*r.