Safety Valve Operation

[Brian HParticipant @brianh50089]

Manually letting off steam

[Brian HParticipant @brianh50089]

I have bought a pair of safety valves to the Gordon Smith design and was surprised that there is no facility to operate them manually to check operation with the boiler in steam.

Is this OK under the regs(used to be the Green Book) and has anyone modified their valves to allow operation manually?

Brian

[Robert Atkinson 2Participant @robertatkinson2]

The boiler test code 2018 volume 2 section 13.1.5 says

"It is considered good practice that every time steam is raised in a
boiler that if possible the safety valve is tested by lifting the spigot
to allow steam to escape. This action reduces
sticking of balls etc."

so sounds like it's not mandatory but I think you would need a good reason not to use a testable valve. Maybe boiler inspector can comment.

[Jon LawesParticipant @jonlawes51698]

I bet I'd scald myself.

[Paul KempParticipant @paulkemp46892]

'Testing' them at anything other than operating pressure proves nothing other than there is a free passage of steam so I don't see any real value in the practice. Few full size safety valves have that facility. For myself I am far more interested in that the valve lifts at the set pressure in normal operation. When lighting up a boiler the first thing I want to know is its operating pressure indicated by the red line on the gauge, no line no lighty, do not pass this point. Then I want to verify the water level and that the gauge glass passages are clear, with both these conditions satisfied plus an external visual inspection I proceed to raise steam, to the indicated operating pressure and confirm the safties lift – if not then either the pressure gauge is out of whack or the valves defective – further investigation required and until resolved the boiler is not fit for service. Lifting the valve manually at less than its operating pressure is far less important than a full pressure test and as Jon says not easy to do safely especially on a large or full size boiler,

Paul.

[John RuddParticipant @johnrudd16576]

Safety or relief valves are designed so no manual intervention is required….

I have worked on high pressure systems ( gas/steam/air/freon) where relief valve operation is a HSE demonstrable requirement….

[Brian HParticipant @brianh50089]

I think that Robert Atkinson2 has the right idea and I would prefer to lift the valve just to make sure it hasn't stuck through no being used etc.

Brian

[Paul LousickParticipant @paullousick59116]

As stated, it is good practice to ease the safety valve at every startup to ensure that is not stuck. Also good practice to raise the pressure to maximum while monitoring the pressure to see if the valves are set correctly and releases pressure. We do this all the time on full size steam engines.

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