[Hallb-engineering] Fwd: Lesson Learned "Heat from Brazing on Copper Air Line Causes Soft-Soldered LO Valve to Come Loose on 100 Psi Air Line - Los Alamos National Laboratory"
tilles at jlab.org
Tue Jul 16 09:36:56 EDT 2013
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From: mbailey at jlab.org
To: mbailey at jlab.org
Cc: robertl at jlab.org
Sent: Tuesday, July 16, 2013 9:00:16 AM
Subject: Lesson Learned "Heat from Brazing on Copper Air Line Causes Soft-Soldered LO Valve to Come Loose on 100 Psi Air Line - Los Alamos National Laboratory"
Heat from Brazing on Copper Air Line Causes Soft-Soldered LO Valve to Come Loose on 100 Psi Air Line - Los Alamos National Laboratory
Statement of Lessons Learned
For a copy of the full report and pictures, see Attachments on Lessons Learned page.
There is no formal industry requirement on what distance should be between connections when soldering copper tubing/piping, careful consideration should be taken to ensure that heat applied to one joint being soldered does not impact another upstream. The high temperature required to melt filler metal during the hard solder process can cause failure of soft-solder joints upstream. Discussion of Activity
On March 28, 2013, LANL workers were brazing a copper process air line for a construction tie-in to an existing facility system at Technical Area 55. The process air was isolated with a lockout/tagout (LOTO) for personnel protection. The heat from the brazing softened the soft solder on the valve with the LOTO. The valve came off the existing facility piping, allowing process air to escape into the room. The process air was isolated after the event by utilizing another isolation valve. Work was paused and management was informed. The valve was replaced the same day with a three-way silver brazed valve. Radiological surveys were completed and the continuous air monitors (CAMs) were reviewed for any indication of radiological contamination; there was none. There were no injuries to personnel. Analysis
The apparent direct cause of this event was "defective or failed material" in that the soft solder at the gate valve joint failed, allowing compressed air into the room. The apparent root cause was that the special circumstances and/or conditions associated with the soldering/brazing were not identified in the job scope process and incorporated into the work package. It was also noted that the workspace had limited lighting and scaffolding in the area made for cramped conditions. Recommended Action
None for Jefferson Lab at this time.
The corrective action in this event required the implementation of adequate LOTO point selection criteria during work package planning and execution to ensure LOTO integrity remained intact during work. Although there is no formal industry requirement or guidance on what distance should be between connections when soldering, careful consideration should be taken to ensure that heat applied to one joint being soldered does not impact another upstream.
The following actions can be taken to avoid impacting other joints in the system when soldering or brazing:
-- Inspect joints near the one being soldered and determine if a soft solder or hard solder technique was used.
-- Consider using wet rags to minimize heat travel upstream
-- Consider alternatives to soldering joints on copper and instrument piping/tubing, such as employing brazed, flanged, compression, or threaded joints that meet institutional requirements.
7/16/2013 8:37:29 AM by Bailey, Mary Jo
Submitted to those current in �SAF150: WELDING SAFETY training
Summary Lesson ID: 446
Doc ID: 2013-JLAB-446
Priority: Best Practice
Safety Related: YES
Originator: Bailey, Mary Jo
Issued: 7/16/2013 8:35:48 AM
Approved By: Bailey, Mary Jo
Approved On: 7/16/2013 8:37:29 AM
Contact: Robert B. Stuewe, rstuewe at lanl.gov, 505-665-1392
Queued Emails: 0
Sent Emails: 0
Viewings: 1 times Attachments
* DOE Lessons Learned - WeldingPic1.pdf
* DOE Lessons Learned - Welding1.pdf
* Hot Work
* Welding, Cutting, Brazing & Grinding
* SAF150: WELDING SAFETY
* *Division Safety Officers (DSOs)
* *Safety Wardens
* *ESH&Q Liaisons
* *DOE Notification
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