Safety instrumentation systems recommendations

Increasingly, newer fired process heater installations are adding more fuel-air combustion controls and safety instrumentation systems. However, the decision on the extent of fired heater combustion controls, instrumentation, and safety systems to employ is fundamentally a loss prevention and risk tolerance issue, rather than a fire protection one. The following recommended practices, codes and standards apply to fired heater and dryer controls and instrumentation ... 

The following process is recommended for all changes to programmable safety instrumented systems ... 

Solution Many manufacturers recommend proof test procedures for low demand safety instrumented system applications. The information is found in the safety manual. That document may be part of another manual or may be a separate document. Referring to the safety manual section of a pressure transmitter (Ref. 4), proof test options with associated coverage factors are given (Figure 7-2). The test titled Five Year Proof Test has a manual proof test coverage of 65%. The test titled Ten Year Proof Test has a manual proof test coverage of 99%. 

Innal, F. et al. 2006. An attempt to understand better and apply some recommendations of lEC 61508 standard. In Langseth, H. Cojazzi, G. (eds). 30 ES R D4 seminar Proc., Trondheim, 7-8 June 2006. Ispra ESReDA International Electrotechnical Commission [lEC] (1 ) 2004. lEC 61511, Functional safety - Safety instrumented systems for the process industry sector-All parts. Geneva lEC... 

Recommendation 4 - The entire system and all components of the storage tank overfill prevention system are to be engineered, operated, and maintained to achieve and preserve an appropriate level of safety integrity in accordance with the requirements of industry standards for safety instrumented systems . Part 1 of BSEN 61511 [9]. 

Procedures shall be implemented to ensure prompt follow-up and satisfactory resolution of recommendations pertaining to the safety instrumented system arising from... 

The validation activities including validation of the safety instrumented system(s) with respect to the safety requirements specification including implementation and resolution of resulting recommendations. 

PHA methods. Even from each of the PHA types there could be variety of results that is dependent on the outcome. These results could be just a list of hazards or accidents they could be a detailed list with priority of action or input for a further study of safety instrumentation systems with alternatives or input for a QRA. As all methods are not capable of providing all kinds of results it will be the responsibility of team leader and the team to decide on the issue. From the discussions in Clause 1.2 almost all PHA is capable of giving a list of hazards and recommendations for mitigation. If, however, further detailing such as prioritization of risk or quantitative analysis is necessary then the team needs to opt for ETA, ETA, etc. 

Safety instrumented system (SIS) SIS is meant to prevent, control, or mitigate hazardous events and take the process to a safe state when predetermined conditions are violated. An SIS can be one or more SIFs, which is composed of a combination of sensors, logic solvers, and final elements. Other common terms for SISs are safety interlock systems, emergency shutdown (ESD) systems, and safety shutdown systems (SSDs). So, SIS is used as a protection layer between the hazards of the process and the public. SIS or SIF is extremely important when there is no other non-instrumented way of adequately eliminating or mitigating process risks. As per recommendations of standards lEC 61511 2003 (or ANSI/ ISA-84.00.01-2004), a multi-disciplinary team approach following the safety life cycle, conducts hazard analysis, develops layers of protections, and implements an SIS when hazardous events cannot be controlled, prevented, or mitigated adequately by non-instrumented means. 

Chapter 5 is devoted to safety in offshore oil and gas industry. Some of the topics covered in this chapter are offshore industrial sector risk picture, offshore worker situation awareness concept, offshore industry accident reporting approach, and offshore industry accidents case studies. Chapter 6 is devoted to case studies of oil tanker spill-related accidents, oil tanker spill analysis, and oil spill causes. Chapter 7 presents various important aspects of human factors contribution to accidents in the oil and gas industry and fatalities in the industry. Some of the topics covered in this chapter are human factors that affect safety in general, categorization of accident-related human factors in the industrial sector, categories of human factors accident causation in the oil industry, and recommendations to reduce fatal oil and gas industry incidents. Chapter 8 is devoted to case studies of maintenance influence on major accidents in the oil and gas industry and safety-instrumented systems and their spurious activation in the oil and gas industry. 

A two-out-of-three safety circuit system should be Installed at all reactors. Safety circuits should be powered from station batteries. All Primary Critical or Continuity Sensitive Instrumentation should be supplied from these same batteries. Static inverters are recommended for conversion of D. C. to A. C. for instrument use. (System details are referenced to Figure 5, sheets 1 and 2). 

Other Safety Guides present recommendations relating to the earthquake scenario, but in the framework of the design of specific plant systems Ref. [5] deals with the reactor coolant system. Ref. [6] with the containment system. Ref. [7] with the emergency power system, and Ref. [8] with instrumentation and control systems. 

Make sure that lessons learned and corrective actions and recommendations are plugged back into the safety management system, this also includes new training, new procedures, and maybe new equipment or instrumentation. 

Eagle Richer recommend their active lithium-thionyl chloride cells for micropower sources in advanced application areas, e.g. airborne instrumentation, undersea communications, mineral exploration, remote site monitoring safety controls, security, and space and/or defence systems. 

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