Feed water pumps

[johnp]

Is it ok to have all three boiler feed pumps going into the same inlet? (hand pump, steam injector, and cross head driven pump.

[preaton]

OK but 2 separate inlets is better. Redundancy is always good for safety.

If I was plumbing into a single inlet, I would probably have an immediate stop valve then a T to separate stop +check valves for each separate source. This gives you the maximum redundancy. If one check valve hangs up then you can still feed through the other source while you are sorting it out.

Cheers

Paul

[fredrosse]

The ASME Boiler and Pressure Vessel Code requires an isolation valve, with a check valve immediately upstream for a feedwater connection. This single check valve is independent of any check valves on pumps or pump discharge headers.

The Code shows no examples where more than one feedwater connection is provided. I would guess more than one is permitted, although I see no real reason for more than one. When speaking of redundancy, how could this single feedwater connection fail, in such a way that an alternate feedwater connection would be used?

[johnp]

So i should have a check valve after of each pump

[fredrosse]

The rules say you must have an isolation valve and check valve on the pipe to the boiler, and is silent as to the valve arrangement upstream of these two valves.

For reciprocating pumps with their own internal check valves extra check valves between the pump and feedwater header would be redundant, and can be installed.

For an Injector (or other type of pump), an internal check valve may be in place, if one is not, then a check valve on the discharge to the feedwater header would be a good idea.

Isolation valves on the discharge of individual feedwater pumps is also generally a good idea, although optional for many installations.

Remember to provide pressure relief protection if the pump discharge can be isolated, and the pump can produce pressures that exceed the design pressure of the piping. A small reciprocating pump that is engine driven can often produce enormous pressures, the one on the Margaret S. can easily produce way more than 2000 PSI if isolated. I have a relief on that pump. My manual feed pump can only produce about 500 PSI with me standing on the pump lever, so I don't need a relief valve on that one.

The attached picture shows a small steamboat feedwater heater that was isolated, and had no relief protection. The engine driven pump pressurized the feedwater side so high that it ruptured the tube inside the heater. The exhaust steam connections were also isolated, so the shell of the heater was then pressurized until it ruptured.

[johnp]

is this ok?

[87gn@tahoe]

I would put a valve at all* (see below)* connections to the boiler (feed, gauge glass, main steam, etc), right at the boiler in case of a plumbing or check valve failure.

EXCEPT for the safety valve, DO NOT put any valve between the safety and the boiler.

[farmerden]

In this video you can clearly see how water is placed in my boiler. On the left side there is a vertical black pipe coming from the hand pump [not shown] ,it then turns left,thru a check valve,then thru a stop valve and into the boiler.In front of that black pipe is the injector,then another check valve and into a T,then up to a stop valve and into the boiler.This setup allows me to put water into the boiler or the hotwell. On the left side of the engine is the water coming up from my boiler feed pump ,thru a check valve,then thru a stop valve and into the boiler[/url