Boiler Code

Common Header-Boiler Rule

When two or more boilers are connected to a common header, the connection from each boiler having a manhole opening shall be fitted with two stop valves having an ample free-blow drain between them

Boiler

a closed vessel in which water under pressure is transformed into steam by the application of heat

Pressure Vessel

a closed vessel in which the source of pressure is external to itself. Any pressure vessel not identified as a boiler

Inspection

boiler must be HP, externally steaming, and a 6-month extension can be requested for internal inspections

Compressed Air Tanks

inspected every 2 years if over 50 psi

Refrigeration Equipment

inspected every year if over 20 tons

Pressure Gauge

- siphon or u-shaped tube (Bourbon Tube)

- within 2% accurate while reading 1 1/2 times the MAWP

Pigtail (Siphon)

- condensate within protects gauge from high temps while the pressure is still sensed

- test connection on side for inspector

Bourbon tube

most accurate gauge when in the middle of range (fluctuations are easier to notice)

- hydrostatic test at 1 1/2 x MAWP

Inspector Testing

inspector test connection must be with a 1/4 '' or 1/2'' NPT mounting stem

Bodyweight Test

use a known weight and use it to set the pressure gauge properly

Boiler Vent Material

1/2'' or 1'' steel pipe

Boiler Vent

open for startup and shutdown

- keep closed for shutdown if you plan to turn it back on soon, followed by nitrogen to maintain drum pressure

Superheater Vent

close once clear steam, superheater outlet header, and open for startup/steam stop valve is close

Main Steam Stop Valves

located at steam outlets, must be gate or globe

- chain or motor-operated

- non-return

OS&Y

outside screw and yoke valve

Free Blow Drain

trough installed underneath so it can terminate there

- drain must be visible

Stop/Non-Return Valve

when 2 stop valves are used and 1 is a non-return, the NON-RETURN is placed as close to the boiler as possible

Pipe Fittings

flanged

threaded

socket welded (insert pipe)

Butt welded (weld touching ends)

Pressurtrol

package boilers

- pressure adjustment for max cut off pressure (maintains right below if no differential adjustment)

- differential adjustment determines the range of operation above and below the pressure adjustment

-bellows move the mercury switch

Water Column Connections

connects to the gauge glass via a steam/water connection

Empty Guage Glass

blowdown it as well as the water column to check first - shut down boiler if clogging isn't the issue

Surface Blow

found at/lowers water level and reduces foaming

Water Measurement (under 400 psig)

at least 1 direct reading gauge

Water Measurement (above 400 psig)

2 direct or 1 direct and 2 remote (out in plant)

Water Column

a pipe behind gauge glass

1. reservoir for gauge glass so the level can be read without disturbances

2. traps sediment

3. allows steam/water connection to be high/low

4. high + low water level alarm

Water Column Material (under 250 psi)

cast iron

Water Column Material (250 psi-350 psi)

malleable iron

Water Column Material (above 300 psi)

steel

Water Column Shut-Off Valves

through flow construction so you can look in (connection to gauge glass)

Water Column Pipe Connections

readily accessible

Tubular Gauge Glass

glass between valve - held by a nut, washer, + packing ring

- lowest water level is 3" above top tube row or 2" above LPWL (lowest permissible water level)

Gauge Glass - Boiler Connections

rear, ends, sides

Flat Guage Glass

Mica, 2 flat glass plates bolted to steel housing, and over 400 psi

Mica

thin cut rock that prevents steam from etching glass in gauge

Try (Gauge) Cocks

located at water column

Water Level Blowdown (IMPORTANT)

1. close low gauge glass valve

2. open drain cock (steam connection is open during it)

3. close drain cock and open low valve

4. closed upper gauge glass valve and open drain (water connection is open and water comes out)

5. close drain and open top (water returns)

Tubular Gauge Glass Replacement

1. shut off water/steam isolation valves

2. Ensure there's a secondary way to check water level

3. open drain valve

4. remove glass then cut some to install

5. slowly heat glass via the steam connection and drain

Safety Considerations

- steam/water etches glass if there's a leak at connections

- gauge glass steam/water valves open for operation

- don't tighten nuts under pressure for leaking glands

Feedwater Regulator

water returning=steam leaving

Single Element Feedwater Regulator

drum level/pressure measure with a single control loop

- utilize thermoexpansion or thermohydraulic

Thermohydraulic

feedwater regulator using bellows

Thermoexpansion

thermostatic at drum NOWL

- connects the steam drum to the feedwater pipe

- a dropping water level causes steam to fill the thermostatic, causing it to pull an actuated valve in order to bring in more feedwater

Two Element Feedwater Regulator

-type Bailey or Copes

- measure water level + steam flow

- control loop regulates feed flow based on steam flow changes WHILE the 2nd loop corrects the feed flow

Three Element Feedwater Regulator

steam/feed flow AND drum level

- regulates based on the ratio of feed input to steam output

- multiple control valves and feed pumps