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Safety Instrumented Systems
ANSI/ISA S84.00.01-2003, Application
of Safety Instrumented Systems for the Process Industries, 2003, (called
S84 here) addresses the application of Safety Instrumented Systems (SIS)
to take a process to a safe state when predetermined conditions are
violated, such as set points for pressure, temperature, level, etc. Its
objective is to define requirements for SIS. SIS are also called
Emergency Shutdown Systems, Safety Shutdown Systems, and Safety
Interlock Systems. SIS provide safety control functions and complement
the Basic Process Control System (BPCS) which provides normal process
control.
OSHA has endorsed S84 as a
"national consensus standard" in a March 23, 2000 OSHA letter
to ISA. This letter states that S84 is considered "a recognized and
generally accepted good engineering practice" for SIS. Paragraph
(d)(3)(ii) of the Process Safety Management (PSM) standard specifies:
"The employer shall document that equipment complies with
recognized and generally accepted good engineering practices". The
letter states that in evaluating whether an employer's engineering
practices with respect to SIS comply with PSM, OSHA would consider,
among other factors, whether the employer meets the requirements of S84.
In the letter, OSHA states that it is
also important to note that there is a large percentage of processes
which are not covered by PSM which may include SIS covered by S84. OSHA
states that the employer may be in violation of the General Duty Clause,
Section 5(a)(1) of the OSH Act, if SIS are utilized which do not conform
with S84, and hazards exist related to the SIS which could seriously
harm employees. Consequently, this means that companies must comply with
S84, not only for PSM-covered processes, but also for other processes
that use SIS where hazards to personnel may be present.
Services Offered
Primatech helps clients modify their PSM programs to
address SIS, such as additions to process safety information, PHA,
operating procedures, and mechanical integrity. We also help to
establish SIS Safety Requirements Specifications and assist in
developing procedures for SIS installation, commissioning, testing,
operation, maintenance and change reviews. Primatech also facilitates
the performance of LOPA studies by a team of facility personnel to help
determine what safety integrity levels (SIL) are needed for SIS.
Primatech offers the training courses
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