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6112 Appendix T1 Interlock Bypass Procedure |
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1.0
Purpose
Jefferson
Lab’s Interlock Bypass Policy requires that bypasses be identified by an
applied Interlock Bypassed tag and/or electronic entry in the Accelerator
Bypassed-Interlocks Log (ABIL).
Jefferson Lab employs the fail-safe practice of identifying bypasses
before being installed and uninstalling bypasses before removing the associated
identification.
This procedure outlines the
administrative requirements for the identification, installation, and tracking
of bypassed interlocks on equipment at Jefferson Lab.
NOTE: This policy does not apply to equipment
associated with the Personnel
Safety System (PSS), which is governed by the Jefferson Lab Personnel Safety System Configuration Control Policy. Any maintenance or service work associated with hazardous energy
sources is subject to Lock,
Tag, and Try (LTT) as described in ES&H
Manual Chapter 6110 Lock, Tag, Try (LTT) Program. |
It can be difficult to determine if a specific item is an
interlock. For example, a water valve is not an interlock, but an associated
sensor that detects water flow, temperature, pressure, or valve position and
constrains the operation is part of
an interlock.
Bypassing
interlocks can be accomplished by installing a physical wire or jumper,
modifying software, or changing process variables or setpoints. The specific steps to
be used when bypassing system interlocks are determined by the status of the
equipment (i.e., whether the equipment is “in-service” or “out-of-service”).
This appendix provides the
process steps for safely installing and removing system interlock bypasses according
to the status of the equipment.
This appendix is written in
coordination with ES&H Manual Chapter 6112 Interlock Bypass Policy. All
applicable content within the chapter applies to the procedure outlined in this
appendix.
·
Determine the status of equipment
for which the bypass is to be installed and follow the applicable process steps.
·
Before installing
bypass on equipment, ensure completed Interlock Bypassed tag is attached to equipment
and/or an ABIL entry is made.
·
After removing
bypass on equipment, ensure Interlock Bypassed tag is removed and/or ABIL entry
is updated.
Equipment is “in-service” when
the physical, critical connections remain in place, even if a switch is thrown
or a fuse is removed. Only actions like
physically removing the equipment or disconnecting critical cabling change the
status to “out-of-service”.
An Interlock Bypassed tag and
ABIL entry are required for each bypass installed on “in-service” equipment,
with exceptions outlined in Table 1.
Table 1 - Exceptions
IF |
THEN |
Changing
a software process variable (e.g., masking a fast shutdown (FSD)
node or bypassing an ODH head through software) |
·
ABIL entry is required. ·
Interlock Bypassed tag is not required. |
Immediate maintenance
(i.e., bypasses made during repairs to correct conditions that impede the
scheduled program) |
·
Interlock
Bypassed tag
is required. ·
ABIL entry is
not required. |
Conclusion
of immediate maintenance event
occurs when time needed for repairs must be extended for a significant amount
of time (short breaks during maintenance do not apply, but large breaks in
maintenance, such as leaving for a meeting, do apply) |
·
Interlock
Bypassed tag
is required. ·
ABIL entry is required. |
Step 1:
Add
new entry in ABIL (see 4.2.2).
o
If
this is immediate maintenance, ABIL entry is not
required; go to Step 2.
Step 2:
Apply
Interlock Bypassed tag (see 4.2.1).
o
If
changing a software process variable, ABIL entry is required, but Interlock
Bypassed tag is not required; go
to Step 3.
Step 3:
Install
bypass.
Step 4:
If
equipment is still “in-service” at conclusion of immediate maintenance event:
·
Add
new entry in ABIL (see 4.2.2).
·
Record
serial number on applied tag.
4.1.2
Out-of-Service
Equipment
Equipment is “out-of-service”
when the physical, critical connections have been removed. Equipment that
remains in place, but critical cabling removed, or equipment that has never been installed, is considered to
be “out-of-service”.
An Interlock Bypassed tag is
required for each bypass installed on “out-of-service” equipment. An ABIL entry
is not required, unless the equipment is placed in service while the bypass is
still in place.
Step 1:
Apply
Interlock Bypassed tag (see 4.2.1).
Step 2:
Install
bypass.
Step 3:
If
equipment is placed in service while bypass is still in place:
·
Add
new entry in ABIL (see 4.2.2).
·
Record
serial number on applied tag.
4.2.1
Interlock Bypassed Tag (Figure 1)
Step 1:
Complete Interlock
Bypassed tag for each bypass:
· Serial number generated by ABIL, if applicable
·
Name of person
installing bypass
· Date
· Purpose
· Location of the jumper
· Comments as appropriate
Step 2: Apply Interlock Bypassed tag in a location obvious to anyone who would be removing the bypass. This location may be on a larger piece of equipment that includes the equipment for which the bypass is installed.
Figure 1 - Interlock Bypassed Tag
Front Back
4.2.2
ABIL
Entry (Figure 2)
Step 1:
Hover mouse over gray
tabs near top of webpage for description/examples of fields.
Step 2:
Click “Add New” in the Accelerator
Bypassed-Interlocks Log (ABIL).
Step 3:
Enter requested information,
and be sure function and purpose are clear. “Function” describes what the
interlock does; “Purpose” describes the reason for leaving bypass installed.
Step 4:
Record serial number
generated by ABIL on associated Interlock Bypassed tag, if applicable.
When a
system interlock bypass is removed from the equipment, perform the applicable
step(s):
Step 1:
Uninstall bypass
Step 2: Remove applied Interlock Bypassed tag from equipment
Step 3:
Update appropriate ABIL entry
5.0
Revision Summary
Revision 0.2 – 10/13/16 –
Periodic Review; updated
TPOC from R.Lauze to K.Baggett
Revision 0.1 – 12/17/13 – Added invisible links to “Martha”
program in subparagraphs per MJ.Bailey
Revision 0.0 – 08/05/13 – New content written to reflect
current laboratory operations
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ISSUING
AUTHORITY |
TECHNICAL POINT-OF-CONTACT |
APPROVAL
DATE |
REVIEW
REQUIRED DATE |
REV. |
|
|
ES&H Division |
10/13/16 |
10/13/21 |
0.2 |
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