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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22347
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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What is the range of a safety valve settings for a boiler operation

Customer Question

What is the range of a safety valve settings for a boiler operation at 1000 psi
Submitted: 7 years ago.
Category: HVAC
Expert:  BillyHvac replied 7 years ago.
For each boiler, one (1) or more safety valves on the boiler shall be set at or below the maximum allowable working pressure. If additional valves are used, the highest pressure setting shall not exceed the maximum allowable working pressure by more than three (3) percent. The complete range of pressure settings of all of the saturated steam safety valves on a boiler shall not exceed ten (10) percent of the highest pressure to which any valve is set. If two (2) or more boilers operating at different pressures and safety valve settings are interconnected, the lower pressure boilers or interconnected piping shall be equipped with safety valves of sufficient capacity to prevent overpressure considering the generating capacity of all boilers. If the boiler is supplied with feed water directly from pressure mains without the use of feeding apparatus (not to include return taps), safety valve shall not be set at a pressure greater than ninety- four (94) percent of the lowest pressure obtained in the supply main feeding the boiler.
Customer: replied 7 years ago.
so you are saying that for a safety valve for a boiler operation at 1000 psi. the safety valve range is plus or minus 10 percent
Expert:  BillyHvac replied 7 years ago.

If you have a moment I will pull my code book and verify.

 

Billy

Customer: replied 7 years ago.
i will be online but have to leave my office for 10minutes or so. thanks.
Expert:  BillyHvac replied 7 years ago.

5.2 When two or more PSVs are used to protect one piece of equipment and the

required capacity is provided by one PSV only one device need be set at or

below the MAWP. In no case shall a PSV be set at a pressure greater then

105% of the MAWP for ASME VIII vessels. For ASME I Power Boilers the

maximum set pressure of additional PSVs shall not exceed the MAWP by

more than 3%.

The complete pressure range of all saturated steam valves

shall not exceed 10% of the highest pressure to which any valve is set.

For

ASME IV Heating Boilers additional valves may have a set range not to

exceed 6 PSI above the MAWP of a boiler up to and including 60 PSI and 5%

for those having a MAWP exceeding 60 PSI. The set pressure shall include

the effects of static head and constant back pressure.

 

Billy

 

 

Customer: replied 7 years ago.
<p>thanks for looking that up. but i'm still not sure that answer the question because they are not saying the MAWP is 1000. They are asking for the range of SV settings for the boiler operation at 1000 psi. Do you follow what i'm saying. The boiler could Have a MAWP of 1500 so that would be the setting for the SV to pop. Sorry to make this hard.</p>