Posted by Carl on June 04, 2000 at 12:02:05:
In Reply to: Safety/Relief Valves posted by Jack on June 03, 2000 at 21:41:58:
: So tell me what you think about hand lifting safety or relief valves on a periodic basis while under pressure to ensure a positive flow path.
: I have a State Safety Engineer in California telling us we should be doing this "frequently",but wouldn't define this what frequently was. He hinted that shiftly or daily would sufice. We have two 150 BHP scotch marine fire tube boilers.
: Now I'm not saying he's wrong, bcause I know what his intentions are, but there are negative consequences to this which may only compound the problem and or create problems for you.
: The code isn't necessarily clear on this, it suggests you should do it, but could cause wire drawing across the seats.
: In the 10 years I was in the Navy I never heard of this nor had this done in any plant that I was in.
I agree the testing is necesary too. However, I do not have a current Title 8 California Law to refer to by which I could see California specific law regarding testing.
You do not say what pressure the boilers are under. I will assum, as I have never seen a CB boiler above 400 psig, that they are typical 150 psig boilers. The National
Board of Boiler and Pressure Vessel Inspectors indicates at pressures below 400 psig to manualy check them every 2 months. Annually they should be pressure tested. This
either can be on the boiler or sending them to a VR qualified repair facility. Some insurance companies require monthly tests still. It also depends on your experience
with the valves, i.e., if they have failed to lift or close properly, more frequent tests may be good practice. My thoughts there would be the cost of replacement is fairly
reasonable so just change them out if they are in bad condition, judgement call. Go to the National Boards web site at www.nationalboard.org and review a few of their "Classic"
articles on safety valves. Hope this helps.
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