Operations and Maintenance

ANSI/ISA 84.00.01-2004 (IEC 61511 modified) requires that the operation, maintenance, and testing procedures for the Safety Instrumented System (SIS) contain the following:

  • Set points and actions.
  • Hazard that you are trying to prevent.
  • When to use bypasses.
  • Response to diagnostic alarms – Compensating measures.
  • When to execute a safe shutdown.

As with the design and construction phases of a project SIS-TECH has the maintenance and operations experience to generate the required step by step procedures covering the essential activities and any data that should be collected during the activity. Since we also understand the potential failure modes of SIS devices, the procedures take these modes into account ensuring that the functional tests accurately identify hidden faults while minimizing the chances of a spurious trip during testing. Once the procedures are complete, we provide training or training packages. Our extensive field experience makes our training programs interesting, focused and effective resulting in well trained operations and maintenance staff ready to take ownership to ensure long term lifecycle reliability.



Call SIS-TECH for assistance with any of the following:

Hot Cut-over Procedures

Detailed procedures are used to cut-over the process unit from the existing SIS to the new SIS, while the process is on-line and operating. These procedures are intended to minimize unplanned outages of the operating process unit.

SIS-TECH generates step-by-step procedures that guide the cut-over team through critical steps of the SIS cut-over. The procedures have sufficient detail to allow verification of the following:

  • SIS devices are inspected and tested,
  • SIS is fully functional, and
  • The SIS is on-line and protecting the process.

The procedure outlines the communication required between the cut-over team and the control room operator. SIS-TECH procedures include the following information:

  • Safety Functional Description
  • Operator Assistance Requirements
  • Bypasses
  • Alarms
  • Cut-over Team
  • Cut-over package (procedure and drawings)
  • Inspection
  • Testing
  • Return process to normal service

Operator Training

SIS-TECH can provide operator training for a specified Safety Instrumented System (SIS). This training is typically specific to the following:

  • Unit Startup/Normal Shutdown
  • Safety System Permissives
  • Automatic Shutdown/Recovery
  • System Bypassing
  • Response to Critical Alarms

Development of training material requires a multi-disciplinary team that has experience with the process unit. The team typically consists of representatives from the operations, process, and maintenance departments. Effective training materials enhance operator understanding of the SIS and its potential effect on the process unit. The training course material contains step-by-step procedures with sufficient detail to cover the safe operation of the SIS during startup, operation, and shutdown of the process unit.

Proof Test Supervision

Proof testing is performed to expose dangerous failures that would otherwise remain undetected until a demand occurred, potentially resulting in a process hazard. If off-line testing is performed, a well-planned and executed test program can reduce the time required for testing, thereby minimizing the potential for a start-up delay. As plant reliability programs enable plants to reach longer turnaround intervals, off-line testing opportunities are becoming fewer. In many cases, testing the SIS devices at turnaround is insufficient to meet the integrity requirements. On-line testing presents the potential for spurious trips during the test. SIS-TECH can minimize this risk by providing personnel experienced in procedure development, manpower planning, site supervision, training, and auditing.

Proof Test Procedures

Effective proof test procedures demonstrate the functionality of the SIS devices. SIS-TECH generates step-by-step procedures incorporating sign-off spaces for critical steps. These  procedures have sufficient detail to address testing of the critical device functionality as well as providing verification that the technician has returned the device to service after testing. In addition, the procedure establishes the appropriate communications between the operator and the proof test technician. SIS-TECH procedures contain the following information:

  • Safety function description
  • Safety function drawings
  • Trip values
  • Instrument ranges
  • Testing tolerances
  • Communications to occur between technician and control room
  • Bypass initiation, if required
  • Alarms
  • Indications
  • Back in service notification
  • Test approval