BOILER SAFETY VALVES

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BOILER SAFETY VALVES

• 62B-206

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DEFINITIONS

• LIFT OR POP - REFERS TO THE OPENING OF THE SAFETY
  VALVE
• BLOWDOWN - THE PRESSURE DROP BETWEEN LIFT AND
  RESEATING OF THE SAFETY VALVE
• RESEAT - CLOSING OF THE SAFETY VALVE WITHOUT
  CHATTERING

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DEFINITIONS CONT

• SIMMERING - STEAM THAT LEAKS BY THE SEAT AND DISK
  PRIOR TO THE LIFTING OF THE SAFETY VALVE.
  ACCEPTABLE CONDITION WITHIN 1 OF LIFTING
  PRESSURE.
• CHATTERING - THE RAPID POPPING AND RESEATING OF
  THE SAFETY VALVE

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DEFINITIONS CONT

• GAG - A MECHANICAL DEVICE PLACED ON THE SAFETY TO
  PREVENT THE SAFETY FROM LIFTING DURING TESTING
  AND BOILER HYDROSTATIC TESTS

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REQUIRED TESTING

• IAW PMS
• WHEN REMOVED OR REWORKED
• AFTER BEING GAGGED FOR HYDRO
• IF LIFTED BY WATER DURING HYDRO WHEN NOT GAGGED
• ANY SIGNS OF TAMPERING

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TESTING HOW ITS DONE

• LIGHT OFF THE BOILER
• PLACE GAGS ON TOP OF BOILER TO WARM AND EXPAND
• PLACE THE BOILER ONLINE WITH EQUIPMENT NECESSARY
  TO SUPPORT SETTING SAFETIES

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ONLINE
ECONO- MZER
MAIN STEAM STOP
OPEN
BOILER
LOCKED OPEN
AUX STEAM STOP
OPEN
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TESTING CONT

• ENSURE BOILER WATER CHEMISTRY IS WITHIN STANDARDS
  
• WHEN STEAM PRESSURE 100 -200 PSI BELOW LOWEST
  SAFETY VALVE PLACE GAGS ON SAFETIES. (EXCEPTIONS
  DO NOT GAG HIGHEST DRUM SAFETY)

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TESTING CONT

• TEST/SET HIGHEST SET DRUM VALVE
• REMOVE GAG NEXT LOWER SET VALVE AND TEST/SET.
• REMOVE GAG FROM SUPERHEATER SAFETY TEST/SET
  SUPERHEATER SAFETY.
• ONCE PILOT VAVLE SET, TEST PILOT SUPHERHEATER
  COMBO.

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MLOCS

• HAND EASING GEAR - CHECK CLEANLINESS,
  LUBRICATION, CABLES PULLEYS AND GEARBOXES FREE TO
  MOVE
• FORK LEVER - CHECK CLEARANCE USUALLY 1/16 SET
  IAW MANUFACTURES TECHNICAL MANUAL

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MLOCS

• LOCKS AND SEALS - CHECK FOR SIGNS OF TAMPERING
• VISUAL

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BOILER SAFETY VALVES

• 62B-206