ASME Section IV Pressure Relief Valves and Devices
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Questions and Answers

What type of safety valves are required for each steam boiler according to ASME Section IV?

  • Diaphragm type
  • Piston type
  • Spring pop type (correct)
  • Pilot operated type
  • What is the maximum pressure at which the safety valves are sealed to discharge in a steam boiler, as per ASME Section IV?

  • 20 psi
  • 25 psi
  • 30 psi
  • 15 psi (correct)
  • According to ASME Section IV, what is the minimum allowed size for a safety valve for a steam boiler?

  • NPS ½ (DN 15) (correct)
  • NPS 1 (DN 25)
  • NPS ¼ (DN 10)
  • NPS ⅜ (DN 9)
  • What is the maximum allowable working pressure increase when the fuel burning equipment is installed and operated at maximum capacity, as per ASME Section IV?

    <p>5 psi (35 kPa)</p> Signup and view all the answers

    What requirement does ASME Section IV have for body drain connections of safety valves and safety relief valves in steam boilers?

    <p>A body drain below seat level shall be provided by the Manufacturer</p> Signup and view all the answers

    What is the purpose of the body drain connection provided by the Manufacturer for safety valves and safety relief valves in steam boilers?

    <p>To prevent the collection of condensate around the valve and seat</p> Signup and view all the answers

    Where must safety valves and safety relief valves be installed?

    <p>With their spindles vertical</p> Signup and view all the answers

    What must safety valves be connected directly to?

    <p>A tapped or flanged opening in the boiler</p> Signup and view all the answers

    Where must safety valves and safety relief valves be located?

    <p>In the highest practicable part of the boiler proper</p> Signup and view all the answers

    What must not be placed between the safety or safety relief valve and the boiler, or on discharge pipes between these valves and the atmosphere?

    <p>No shut-off valve of any description</p> Signup and view all the answers

    What is a requirement for the discharge pipe of the safety valve?

    <p>It must be as short and straight as possible</p> Signup and view all the answers

    What is the maximum allowable working pressure for a hot water heating or supply boiler, as per ASME BPVC IV, Part HG-400.2?

    <p>Specified by ASME</p> Signup and view all the answers

    What is a key difference between safety relief valves and safety valves?

    <p>Safety relief valves have adjustable blowdown rings, while safety valves do not.</p> Signup and view all the answers

    What causes frequent operation or water leakage from safety relief valves?

    <p>Presence of scale or chemical residue on the valve seat</p> Signup and view all the answers

    What should never be done to the outlet of a pressure relief valve?

    <p>It should never be plugged</p> Signup and view all the answers

    What can cause frequent safety relief valve operation in hot water heating systems?

    <p>A waterlogged heating system</p> Signup and view all the answers

    What should happen if safety relief valves open frequently during normal plant operation?

    <p>The cause should be found and remedied</p> Signup and view all the answers

    What is the requirement for the location of safety valves and safety relief valves in heating boilers?

    <p>They must be located with their spindles vertical.</p> Signup and view all the answers

    What is a specific requirement for the discharge pipe of a safety valve?

    <p>It must be properly drained to prevent collection of water.</p> Signup and view all the answers

    What should never be placed between the safety or safety relief valve and the boiler, or on discharge pipes between these valves and the atmosphere?

    <p>A shut-off valve</p> Signup and view all the answers

    What is the requirement for the internal cross-sectional area of the discharge pipe of a safety valve?

    <p>It must be greater than the full area of the valve outlet.</p> Signup and view all the answers

    What is a key difference between safety relief valves and safety valves?

    <p>Safety relief valves do not have bottom guides for the disc.</p> Signup and view all the answers

    What is a requirement for safety relief valves in terms of normal operating water level in steam boilers?

    <p>They should be located above the normal operating water level.</p> Signup and view all the answers

    What could cause frequent operation or water leakage from safety relief valves in hot water heating systems?

    <p>Corrosion products on the valve seat</p> Signup and view all the answers

    What is the maximum allowable pressure at which the safety valves must discharge in a steam boiler, according to ASME Section IV?

    <p>15 psi</p> Signup and view all the answers

    What is the minimum allowed size for a safety valve in a steam boiler, as per ASME Section IV?

    <p>NPS ½ (DN 15)</p> Signup and view all the answers

    What is the purpose of the body drain connection provided by the Manufacturer for all safety valves and safety relief valves in steam boilers, according to ASME Section IV?

    <p>To prevent the collection of condensate around the valve and seat</p> Signup and view all the answers

    According to ASME Section IV, what should not be plugged during or after field installation in relation to body drain connections of safety valves and safety relief valves in steam boilers?

    <p>Body drain connection</p> Signup and view all the answers

    In a steam boiler, what safety valve capacity is required when the fuel burning equipment is installed and operated at maximum capacity, as per ASME Section IV?

    <p>To keep the pressure rise not more than 5 psi above the maximum allowable working pressure</p> Signup and view all the answers

    What type of safety valves are mandated for each steam boiler as per ASME Section IV?

    <p>Spring pop type</p> Signup and view all the answers

    Study Notes

    Safety Valves in Steam Boilers

    • Each steam boiler requires two or more safety valves according to ASME Section IV.
    • Safety valves are sealed to discharge at a maximum pressure of 3% above the maximum allowable working pressure.
    • The minimum allowed size for a safety valve in a steam boiler is 1/2 inch (12.7 mm) according to ASME Section IV.
    • The maximum allowable working pressure increase when the fuel burning equipment is installed and operated at maximum capacity is 6% according to ASME Section IV.
    • ASME Section IV requires body drain connections of safety valves and safety relief valves to be full-size, and never plugged during or after field installation.
    • The body drain connection provided by the Manufacturer for safety valves and safety relief valves is to ensure the valve seat and disk are free from sediment and debris.

    Installation and Location of Safety Valves

    • Safety valves and safety relief valves must be installed directly on the boiler, or on the piping connected to the boiler, with no shut-off valves between them.
    • They must be located on the highest part of the boiler, and the discharge pipe must be full-size and unobstructed.
    • No obstruction or valve should be placed between the safety or safety relief valve and the boiler, or on discharge pipes between these valves and the atmosphere.

    Discharge Pipe Requirements

    • The discharge pipe of a safety valve must be full-size and unobstructed.
    • The internal cross-sectional area of the discharge pipe must be at least equal to the full-area of the valve outlet.

    Key Differences and Requirements

    • Safety relief valves are used for liquid systems, while safety valves are used for gas systems.
    • Frequent operation or water leakage from safety relief valves can be caused by improper installation, inadequate overflow, or faulty design.
    • The outlet of a pressure relief valve should never be throttled or restricted.
    • In heating boilers, safety valves and safety relief valves must be located on the highest part of the boiler, and the discharge pipe must be full-size and unobstructed.
    • Safety relief valves must be capable of lifting at a pressure not exceeding the maximum allowable working pressure, and must be set to open at a pressure not exceeding 10% of the maximum allowable working pressure in steam boilers.
    • In hot water heating systems, frequent safety relief valve operation can be caused by excessive water pressure, or inadequate or faulty pressure regulation.

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    Description

    Test your knowledge of ASME Section IV Pressure Relief Valves and Devices, including the code requirements, construction, and operation. This quiz covers the rules for safety valves and safety relief valves installed on heating boilers as per ASME BPVC, Section IV.

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