Drill and tap a fitting?

[kntx]

I need to inject some chemicals into my boiler and have found an existing nozzle on the lower waterwall header. The nozzle is a dead leg with a "grayloc" blind hub on it which we use for cleaning the boiler. There are no valves between the header and the grayloc.

The chemicals will be injected with the boiler online.

To make my connection for the chemical feed, can I drill and tap the blind hub and run stainless steel tubing from the connection to the chemical feed pump; or do I need to use welded pipe all the way? Is there any point at which I can use SS tubing and compression fittings?

If I drill and tap the grayloc, do I have to "recertify" it in anyway?

Thanks in advance for your suggestions.

 

[Xce]

Depends on the pressure of the boiler and your jurisdictions thoughts on modifying fittings.

If your boiler is over 15psi (IE Power Boiler) then the rules in ASME Sec I apply. It says in there that u must have a stop valve between the steam and any instumentation/tubing line attached.

Chances are if they allow you to modify the fitting, they will require u to ensure that there is sufficent reinforment left in the original fitting. Just find out what it was designed to orginally and rerun the numbers.

 

[deanc]

Do you have a feedwater line you could tie into? Makes for a better mix.

 

[kntx]

deanc:

Good suggestion, however the plant chemist only wants this chemical in the boiler, not in the feedwater.

Xce:

The unit is a 2950 psig utility boiler. I was going to use two isolation valves between the boiler and the chemical pump, but I don't think it could be considered an "instrumentation line" since I am using it to inject chemicals. Thanks for the suggestions.

 

[GenB]

You can probably drill and tap a small line 1/2in or less at the feed line right before the first check valve (nearest the boiler)
that way you get off the BEP jurisdiction,
there you can attach instrumentation ss:
valve and checks as required genb