Line B Mechanical Safety Devices Flashcards
Referring to Figure 1, What is this is the ASME symbol for?
Power boiler safety valve
Referring to Figure 2, What is this is the ASME symbol for?
Heating boiler relief valve
Referring to Figure 3, What is this is the ASME symbol for?
Unfired pressure vessel safety valve
Referring to Figure 4, What is this is the ASME symbol for?
Unfired pressure vessel rupture disc
Who can repair and set pressure relief devices?
Organizations authorized by the regulatory authority
What three things must be done to a safety valve to show it has been reserviced by an authorized service organization?
a. Affix a dated service nameplate to the reclosing pressure relief device
b. Use a uniquely embossed seal to seal all adjustable parts
c. Ensure the manufacturer’s nameplate remains on the relief device
What is the recommended time interval for a pressure relief device to be tested?
12 months
What is the recommended time interval for a pressure relief device to be serviced?
3 to 5 years
What type of opening characteristics does a Safety Valve have?
Pop opening from pressure
What type of opening characteristics does a Relief Valve have?
Gradual opening from pressure
Where is the Rupture Disk commonly installed on a boiler?
Upstream in series with a relief valve
The set point on a safety valve can be greater than the Maximum Operating Working Pressure (MAWP) of the vessel or piping.
TRUE / FALSE
FALSE
Referring to Figure 5, What type of vessel would you find this mechanical safety valve on?
High pressure steam boiler
Referring to Figure 6, What type of vessel would you find this mechanical safety valve on?
Unfired steam vessel
A 150 Psig 8,000 MBH boiler has a safety valve with a relief capacity of 8,350 lbs/hr. Can this safety valve safely relieve the boiler?
8000000/970 = 8274Lbs YES
What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 4,600 MBH steam boiler with an efficiency of 82%?
4600X33475/970 3888 lbs/h
What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 400 Horse Power steam boiler with an efficiency of 79%?
400bhpX33475btu/970btu/lb 13,801-4 lbs/h
A 150 Psig, 500 HP, 82% efficient steam boiler has two safety valves, one with a relief capacity of 6,576 lbs/hr and the other at 6,303 lbs/hr. Do the combined relief valves have enough capacity to relieve this boiler safely?
NO 500bhpX33475btu/970 btu per lbs = 17255 6576+6303=12879
A safety relief valve inlet can be smaller than the boiler outlet it serves.
TRUE / FLASE
True
The piping connected to the outlet of a relief valve can be reduced by what size?
The size cannot be reduced
On a steam system, the safety valve must be installed in what orientation?
Vertically
All attached discharge piping for a steam safety valve must be supported___________.
Independently supported
What is best practice when the relief discharge piping from a safety valve is installed vertically to outdoors?
Install a drip pan elbow to allow moisture to drain away form the valve
How many inches should the center-to-center distance from the drip pan elbow to the safety valve not exceed?
24 inches
Referring to Figure 7, the slash in the discharge pipe should be cut at what angle?
45 degrees
Referring to Figure 8, if the safety valve is 3 Inches in size, what must the bet he minimum size of the drain-open to waste pipe be?
3/8 inch
What is the set relief pressure for a propane tank installed on a premise?
250 psi
What is the set relief pressure for a propane tank installed on a vehicle?
312 psi
What is the set relief pressure for a propane cylinder?
375 psi
Where is the primary relief valve installed for a vehicle’s LNG tank?
To the top fill line
Where is the secondary relief valve installed for a vehicle’s LNG tank?
To the vapour withdrawal line
What is the primary relief valve discharge setting set to for a vehicle’s LNG tank?
Set at the MAWP of the tank
What is the secondary relief valve discharge setting set to for a vehicle’s LNG tank?
1.5 times the MAWP of the tank
Referring to the figure below, what must be done to the discharge of this relief valve?
Nothing
