Lessons Learned Database



Title:

Pressurization of Drain Trap

Identifier:

L-2002-OR-BJCX10-0301

Date:

2002-03-05

Lesson Learned Statement:

Whenever performing a design or design change on any vessel configuration, assure inadvertent pressurization of the vessel is considered in the design.

Discussion:

As part of the installation of a permanent pumping system on a hot off gas drain trap at ORNL, a level indicator which utilizes a bubbler was installed for level indication. This bubbler adds a small amount of air (0.6 cubic ft. per hour) to the vessel through a small tube which extends to the bottom of the vessel. Over a long period of time, this addition of air caused the vessel to pressurize, thus preventing the off gas piping system to drain properly into the trap. This caused a low point in the piping to become full of water preventing off gas flow, resulting in a loss of off gas ventilation to the facilities served by this system. A vent equipped with HEPA filtration was added to the trap, thus relieving any pressure and the system operates properly.

Analysis:

Included in discussion above.

Recommended Actions:

When designing or installing any systems that can possibly add pressure to a closed system assure that the operation of the system cannot be detrimentally affected.

Originator:

Bechtel Jacobs Company LLC; Merl Lauterbach; 865-241-5343

Validator:

James Oravits

Contact:

Joanne E. Schutt, (865) 483-0554

Name Of Authorized Derivative Classifier:

C. B. Scott

Name Of Reviewing Official:

D. D. Holt

Priority Descriptor:

Blue / Information

Keywords:

pressurization, drain trap

References:

None
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DOE Function / Work Categories:

Construction
Engineering Design and Construction - Non-Nuclear

ISM Category:

Develop / Implement Controls

Hazard:

Pressurized Systems

End of Lesson!

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