SIS modification

NOTE Modifications to the BPCS, other equipment, process or operating conditions shouid be reviewed to determine whether they are such that the nature or frequency of demands on the SiS wiii be affected. Those having an adverse effect shouid be considered further to determine whether the ievei of risk reduction wiii stiii be sufficient. 

1 Prior to carrying out any modification to a safety instrumented system, procedures for authorizing and controlling changes shall be in place. 

2 The procedures shall include a clear method of identifying and requesting the work to be done and the hazards which may be affected. 

3 An analysis shall be carried out to determine the impact on functional safety as a result of the proposed modification. When the analysis shows that the proposed modification will impact safety then there shall be a return to the first phase of the safety life cycle affected by the modification. 

4 Modification activity shall not begin without proper authorization. 

No reproduction or networking permitted without license from IHS 

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Recently, it is reported that the eutectic Si modification is achieved simply by adding Mg+AI2Ca master alloy instead of pure Mg as an alloying element in Al alloys. Moreover, Mg loss by its affinity to O during melting and holding can be controlled by improvement of oxidation resistance. However, it is not clear that Mg+AI2Ca alloy addition has the same mechanism as that of Ca, a common modifier. The Si modification is closely related to... 

POSTER TITLE Partitioning behavior of AI2Ca and eutectic Si modification with varying heat treatment conditions in AI-7Si-0.4Mg alloy with AI2Ca (PAPER ID 8826)... 

SIS modification Corrections or enhancements to SIS so that the required SIL is achieved and maintained Revised SIS safety requirements Results of SIS modification... 

SIS modification To make corrections, enhancements, or adaptations to the SIS, ensuring that the required safety integrity level is achieved and maintained. 17 Apply appropriate safety lifecycle phase during management-of-change activity. 

Even if an existing SIS has been found to meet the intent of the grandfather clause, changes to the SIS or the process to which it is providing protection may trigger the need to formally re-evaluate its grandfather status. Therefore, MOC procedures should specifically address the issue of SIS modification. An MOC review should be conducted whenever the change potentially affects the process risk. 

Is revised, amended, reviewed, and approved under the control of an information control scheme - 19.2.8 The following is maintained as up-to-date documentation -19.2.9 a. Hazard and risk assessment results and related assumptions SIS equipment with its safety requirements Organization responsible for maintaining functional safety Procedures necessary to achieve and maintain functional safety of the SIS Modification information for all changes to the SIS - (MOC)... 

SIS modifications Correcting, enhancing and adaptation of SIS to ensure that require SIL is achieved and maintained. 17... 

Clause 17 SIS modification Modification of any SIS should be planned, reviewed, and approved prior to changes so as to ensure required safety integrity is maintained even any changed made to SIS. 

Achieving and maintaining safe state Armunciation and fault management Capacity and response time requirements Cff/online periodic testing of SIF SIS modification Interface to non-safety functions Maintenance of SIL for all above functions... 

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