De-rating Maximum Allowable Working Pressure (MAWP) on unfired pressure vessels

To eliminate confusion for inservice inspectors, the practice of de-rating the maximum allowable working pressure (MAWP) for unfired pressure vessels will no longer be allowed or used. This practice was never part of our state boiler law, and guidelines and procedures for de-rating were never uniform or consistent. A "de-rated" unfired pressure vessel could be reinstalled at another location and operated at the original MAWP, causing a serious safety hazard. The inservice inspection guidelines in the NBIC adopted by the state does not address de-rating.

L&I cannot, and will not, accept responsibility for authorizing owners/users to operate unfired pressure vessels in a corroded, deteriorated, unsafe condition. Any thinning in the unfired pressure vessel shell or heads below the Code-calculated minimum thickness would be considered unsafe. Any unfired pressure vessel found in this condition shall be "Red Tagged" VIOLATION-DO NOT USE, by the inservice inspector. The unfired pressure vessel must be immediately removed from service until the following conditions are met:

• A qualified person determines the ASME Code-calculated minimum thickness required (tm) based on UT thickness readings by a qualified NDE Company to the original code of construction.
• The calculations and UT thickness readings are submitted to the Chief Boiler Inspector for review and approval. A record of the results will be entered into the "Jurisdiction Online" database.
• The unfired pressure vessel is subjected to an internal inspection or other required inspections necessary to satisfy the inservice inspector.
• Repairs are done by a qualified "R" stamp certificate holder if weld repairs are necessary to restore the unfired pressure vessel to it's original condition.
• The completed "R-Form" and Traveler is sent to the Chief Inspector for review and filing.

If repairs are not possible, the unfired pressure vessel must be replaced.

Next Board of Boiler Rules meeting

November 15-16 , 2004

Room 3, L&I Service Location, Tacoma

For questions about boiler regulations, fees and forms, please call:

Tony Oda, Technical Specialist

Phone: 360-902-4983

E-mail: odaa235@LNI.wa.gov

Eldolyne Gibson, Secretary Administration

Phone: 360-902-5271

E-mail: gibe235@LNI.wa.gov

Karol Conly, Customer Service Specialist (Supervisor)
Phone: 360-902-5273
E-mail: conk235@LNI.wa.gov

Kay Piesch, Customer Service Specialist
Phone: 360-902-5272
E-mail: piek235@LNI.wa.gov

Annabel Schmidt, Customer Service Specialist
Phone: 360-902-5267
E-mail: schc235@LNI.wa.gov

Q: How does the State of Washington determine the cubic foot volume (?) of a jacketed kettle under its jurisdiction?

A: L&I, with concurrence of the Washington State Board of Boiler Rules, measures a jacketed kettle by multiplying the outside diameter by the overall length to get the cubic foot volume.  That is, the volume of the jacket
including the volume of the contents of the kettle is used as the appropriate measurement.


Q: What are the requirements for pool heaters within the state's jurisdiction?

A: The state of Washington does not use the term pool heater. We consider these units to be water heaters or boilers.
For units sized from 0 – 200,000 Btu, L&I requires them to be built to a
nationally recognized standard like AGA, ANSI, or UL.

Units sized more than 200,000 Btu must be ASME Code-stamped and National Board registered.

Units under 400,000 Btu are not required to meet the requirements of ASME CSD-1 part CF.

Fall 2004
Edition 1

Labor and Industries, Dept. of
Boiler Program
Office: 360-902-5270
Fax: 360-902-4292

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