Part 43 (1/2)

For pressures above 160 pounds, where superheated steah pressure steam lines 4 inches and over should have solid rolled steel flanges and special upset lapped joints In the manufacture of such joints, the ends of the pipe are heated and upset against the face of a holding e, the lapped portion of the pipe being flattened out against the face of thethe desired thickness of the lap When cool, both sides of the lap are faced to fore and gasket The joint, therefore, is a strictlythe lapped ends of the pipe against the gasket

A special grade of soft flanging pipe is selected to prevent breaking

The bending action is a severe test of the pipe and if it withstands the bending process and the pressure tests, the reliability of the joint is assured Such a joint is called a Van Stone joint, though many modifications and iinally introduced

The diaes should be special extra heavy Such flanges should be turned to diameter, their fronts faced and the backs iven for pressures over 150 pounds, all flanges for wrought-iron pipe should be threaded All threaded flanges for high pressure superheated lines 3 inches and under should be ”sees for other than steam lines should be es are frequently used in place of those described with satisfactory results

Fittings--For saturated steas 3 inches and under should be screwed Fittings 4 inches and over should have flanged ends Fittings for this pressure should be of cast iron and should have heavy leads and full taper threads flanged fittings in high pressure lines should be extra heavy, and in low pressure lines standard weight Where possible in high pressure flanges and fittings, bolt surfaces should be spot faced to provide suitable bearing for bolt heads and nuts

Fittings for superheated stearees at pressures above 160 pounds are sorees such fittings should be ”steel castings” and in general these fittings are recos for other than high pressure work may be of cast iron, except where superheated steaht steel” or ”hard s 3 inches and under should be screwed, 4 inches and over flanged

flanges for pressures up to 160 pounds in pipes and fittings for low pressure lines, and any fittings for high pressure lines should have plain faces, saskets High pressure line flanges should have raised faces, projecting the full available diameter inside the bolt holes These faces should be siround joint unions suitable for the pressure required Pipe inch and over should have cast-iron flanged unions Unions are to be preferred to wrought-iron couplings wherever possible to facilitate dis pressure, saturated steam, all valves 2 inches and under ed All high pressure steam valves 6 inches and over should have suitable by-passes All valves for use with superheated steam should be of special construction For pressures above 160 pounds, where the superheat does not exceed 70 degrees, valve bodies, caps and yokes are soive better satisfaction The spindles of such valves should be of bronze and there should be special necks with condensing chah the packing For pressures over 160 pounds and degrees of superheat above 70, all valves 3 inches and over should have valve bodies, caps and yokes of steel castings

Spindles should be of sos should be removable of the sa faces

All salt water valves should have bronze spindles, sleeves and packing seats

The suggestions as to flanges for different classes of service es, except that such flanges are not scored

Autoeneral use with boilers and such use is coulations of certain communities Where used, they should be preferably placed directly on the boiler nozzle Where two or more boilers are on one line, in addition to the valve at the boiler, whether this be an autoate valve on each boiler branch at the main steam header

Relief valves should be furnished at the discharge side of each feed pue side of each feed heater of the closed type

Feed Lines--Feed lines should in all instances bepipe due to the corrosive action of hot feed water While it has been suggested above that cast-iron threaded flanges should be used in such lines, due to the sudden expansion of such pipe in certain instances cast-iron threaded flanges crack before they becohly heated and expand, and for this reason cast-steel threaded flanges will give ht-steel and Van Stone joints have been used in feed lines and this undoubtedly is better practice than the use of cast-steel threaded work, though the additional cost is not warranted in all stations

Feed valves should always be of the globe pattern A gate valve cannot be closely regulated and often clatters owing to the pulsations of the feed pump

Gaskets--For steam and water lines where the pressure does not exceed 160 pounds, wire insertion rubber gaskets 1/16 inch thick will be found to give good service For low pressure lines, canvas insertion black rubber gaskets are ordinarily used For oil lines special gaskets are necessary

For pressure above 160 pounds carrying superheated stea the full available diah pressure water lines wire inserted rubber gaskets are used, and for low pressure flanged joints canvas inserted rubber gaskets

Size of Stea the proper size of steam lines are the radiation from such lines and the velocity of steam within them As the size of the steam line increases, there will be an increase in the radiation[79] As the size decreases, the steaiven quantity of steam naturally increases

There is a her steam velocities, particularly in the case of superheated steaood practice to liure is to-day considered low

In practice the li factor in the velocity advisable is the allowable pressure drop In the description of the action of the throttling calorimeter, it has been de a drop in pressure, the difference in energy between the higher and lower pressures appearing as heat, which, in the case of steah a pipe, may evaporate any condensation present or may be radiated fro surface of the pipe and thus the possible condensation As the heat liberated by the pressure drop is utilized in overco the tendency toward condensation and the heat loss through radiation, the steahly superheated where high steah excess pressure is carried at the boilers to maintain the desired pressure at the pri rather than a loss The whole is analogous to standard practice in electrical distributing systee is adjusted to suit the loss in the feeder lines

In modern practice, with superheated steam, velocities of 15,000 feet per ure is very frequently exceeded

Piping Systen--With the proper size of pipe to be used determined, the most important factor is the provision for the removal of water of condensation that will occur in any system Such condensation cannot be wholly overcome and if the water of condensation is carried to the prime mover, difficulties will invariably result

Water is practically incoh velocities differs little froainst elbows, valves or other obstructions, is the equivalent of a heavy hammer blow that may result in the fracture of the pipe If there is not sufficient water in the syste and vibration in the pipe, resulting eventually in leaky joints Where the water reaches the pri to disruption

Too frequently when there are disastrous results fro wet steam when, as adesign, theof the water in certain parts of the piping fros by the steam The action is particularly severe if stea water, as the waterthe steah the pipes producing a characteristic sharpof the pipe or fittings The ah condensation may be appreciated when it is considered that uncovered 6-inch pipe 150 feet long carrying 3600 pounds of high pressure steam per hour will condense approxih radiation It follows that efficientcondensation water are absolutely iestions as to such means may be of service: