Re: [foxboro] Locking / Disabling equipment

We do the physical things you mentioned as part of a "clearance".  I am =
using the word clearance, as lockout can be a part of a clearance.  In =
addition to the physical measures we "hang" on the DCS display.  This =
means we ask a visual block be placed over the Motor start controls (ie. =
a pump start stop) display.  This red block has an input to reference a =
clearance number. We have rules that insure the motor is in a safe =
condition prior to being able to place the red box over the start stop =
control on screens.   We make the start stop buttons non accessible.
Bryan Wiggins=20
Xcel Energy
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx
[mailto:foxboro-bounce@xxxxxxxxxxxxx]On Behalf Of
brad.s.wilson@xxxxxxxxxxxxxx
Sent: Wednesday, August 24, 2005 12:12 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Locking / Disabling equipment


We're wrestling with the best way to lockout equipment operated by the =
DCS.
Our policy states that the technician doing the work must ultimately be =
in
sole control of the locking "device".  The obvious (and advertised) =
method
to prevent operation of a DCS-controlled device is via the block DISABLE
parameter.  However, anyone with access to SELECT (or any other way to =
get
block default display) also has access to the DISABLE parameter.  Our =
past
practice has been to physically lock a motor starter, disconnect a valve
air supply, remove a valve acruator, etc, rather than rely on the DCS =
for a
secure lockout.

I'd like to know how other users manage lock/tag/try for DCS-controlled
equipment.

Brad Wilson
ExxonMobil Chemical Co
Edison Synthetics Plant
732-321-6115
732-321-6177 fax
Brad.S.Wilson@xxxxxxxxxxxxxx

=20
=20
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