Steam Boiler Check Valve

[sacra]

We have six 9.5 bhp 80# steam boilers tied to a common 10"dia. header. Each boiler has a check valve and shutoff on the steam supply line between the boiler and overhead header (header is only 4 ft up and 2ft over). Is there a potential for condensate accummulation on an idle boiler downstream of the checkvalve? If so, will there be a problem when the idle boiler fires and finally lifts the check valve and condensate column?

 

[ApC2Kp]

sacra,
Good observation of the piping configuration. There will be condensate that accumulates in low pockets and dead legs of steam piping. Either add a small drain valve with or without a steam trap at each low point, or provide some administrative control to slowly bleed steam through a small bypass valve for warmup of a steam line before opening the boiler's main shutoff valve.

 

[quark]

What type of a boiler it is and where is the check vavle placed? If the check valve is in the verticle pipe then there are likely chances of condensate build up.

If your steam pressure is 80psi gauge then specific volume of steam is 4.66694cu.ft/lb and with a very conservative line size of 2" for a 9.5bhp boiler, the steam accumulation will be around 0.00467lb/running foot of pipe after check valve. This will be around 2.1 grams of condensate/linear foot of piping.

Regards,

 

[TBP]

Introducing steam to a line full of condensate can lead to some "interesting" water hammer events.

 

[cme]

Since they're 80# steam, they're ASME Sec1 boilers. You need a stop/check, free-blowing drain valve and stop valve on each boiler.

 

[TBP]

cme - I believe that you only require that arrangement if there's a manhole allowing access to the water side of the boiler. It's not the wrong thing to do, however.

 

[GenB]

If the pipe arrangement does not show any pockets, there will be no water condensate because it has drained back to the boiler, also the pipe arrangement upstreem has to be w/o pockets so the water will drain to the header. Finally the piping has to be so arranged that water will not stay in the pipes.
some to drain to the header and some back to the boiler.
ER