Maintenance or testing design requirements

1 The design shall allow for testing of the SIS either end-to-end or in parts. Where the interval between scheduled process downtime is greater than the proof test interval, then on-line testing facilities are required. 

NOTE The term end-to-end means from process fluid at sensor end to process fluid at actuation end. 

2 When on-line proof testing is required, test facilities shall be an integral part of the SIS 

3 When test and/or bypass facilities are included in the SIS, they shall conform with 

4 Forcing of inputs and outputs in PE SIS shall not be used as a part of 

It is important to define how a SIS is going to be maintained while the process is running. For example, if a transmitter or valve needs to be worked on, consideration needs to be given on how the maintenance department will work on these instruments without causing a nuisance trip while maintaining the safety of the process. 

It should be noted that any limit on the testing period of final elements should be taken into account in the calculation of the PFDgvg of the SIF. 

3 The installation of bypasses may reduce the level of security in a SIS. This reduction in security may be overcome by  

For example, for a 1oo2 sensor configuration, some users like to bypass both sensors at one time but others like to have a separate bypass for each sensor. If both sensors are bypassed, it will be necessary to put measures in place to ensure that risk remains tolerable. Either can be possible, but this should be addressed early in the design. 

No reproduction or n woridng permitted without license from IHS 

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Some records must be retained for specified periods by law. In any case, records should be reviewed periodically to identify repetitive failures which might suggest the need for revised maintenance or design, or more frequent inspections and tests. Conversely, continuously satisfactory results might justify increasing the interval between inspections and tests, subject to statutory requirements. Reliability-based maintenance techniques are valuable tools in this area. 

The short description of all pavement material testing procedures, required by European and American standards, as well as pavement design and maintenance procedures covered, does not, by any means, substitute or replace the standards and procedures developed by the... 

The enterprise assesses the testability of design alternatives to determine built-in test (BIT) and/or fault-isolation test (FIT) requirements to support operational or maintenance considerations. BIT-FIT mechanisms should be provided for those elements that are normally maintained by the operators, customer, or field support engineers. BIT-FIT can be used for diagnostic operations to support lower-level maintenance actions. 

Atmospheric testing techniques and standards described in Chapter 11 are applicable to the splash/spray and atmospheric zones. As indicated previously, these tests give useful information for the design of mcurine structures but in many cases, additional information on the performance of components and component interactions is needed. Full-scale or subscale testing usually is required for the adequate assessment of techniques and materials for maintenance and repair of marine structures. This testing is required not only to determine the performance of the systems but also to derive cost information applicable to the specific application. 

An effective procurement process to ensure that the proper parts, materials, and services are available when needed must be in place for restart. Policies should be established for the procurement of parts, materials, and services that are used in maintenance activities on important-to-safety and safety-related systems. Quality assurance procurement records need to be controlled and maintained to provide documentation for qualified parts and materials and ensure traceability of parts and materials. Deficient or nonconforming items should be resolved in an effective and timely manner. A process should be provided to qualify non-qualified material, A process of acceptable substitution should be provided to obtain parts that are no longer available. Design requirements should be reviewed by appropriate personnel to ensure the upgraded or substitute parts are consistent with the application of the part and component. Retrievable documentation should exist to support the identification of inspection and testing requirements necessary to ensure the qualification and acceptability of the part. Personnel must understand their responsibilities in regard to the implementation of the requirements of the procurement program and policies. 

For many years the usual procedure in plant design was to identify the hazards, by one of the systematic techniques described later or by waiting until an accident occurred, and then add on protec tive equipment to control future accidents or protect people from their consequences. This protective equipment is often complex and expensive and requires regular testing and maintenance. It often interferes with the smooth operation of the plant and is sometimes bypassed. Gradually the industry came to resize that, whenever possible, one should design user-friendly plants which can withstand human error and equipment failure without serious effects on safety (and output and emciency). When we handle flammable, explosive, toxic, or corrosive materials we can tolerate only very low failure rates, of people and equipment—rates which it may be impossible or impracticable to achieve consistently for long periods of time. 

This part considers reactive power control with the use of shunt and series capacitors. The controls may be manual or automatic through electromagnetic or static devices. Protection of capacitors and capacitor banks as well as design, manufacturing and test requirements, installation and maintenance are also covered, the main thrust being on the application of power capacitors. 

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