Safety valves markings

Are safety relief valves marked with "NH3" or "AA", psig valve set to start to discharge, CFM flow at full open, and manufacturer s name and catalog number ... 

On the basis of the flow chart and component list, it can be assumed that seven components are possibly involved in the origin of the undesired incident. They are entered in the upper left field in Table 4.10(a). The complete decision table would have to include 2 = 128 columns. If it is noted, however, that occurrence of the undesired incident UE2 is based on the premise, in every case, that there is excess pressure in the steam network and that the material then fails, this means that only those columns are to be considered which include a 1 (one) in the first two lines. Thus, for the description of the conditions to be observed, the columns entered in the decision table [Table 4.10(a)] remain, with 1 designating the failure of a component, or the undesired behavior of a relevant magnitude and 0 the desired behavior, The system states represented in one column and leading to the undesired event UE2 are marked by an X. This shows that the columns marked X differ in pairs such that in the case of component 9, a 0 or 1 (one) is entered. This means that the component, a safety valve on the tank, has no effect. Then the first 13 columns must be considered, while neglecting component 9. From column 8 it is obvious that the failure" of components W2, Piy. and 31 T already lead to the undesired event, irrespective of whether another component does or does not fail. Therefore columns 1-8 in Table 4.10(a) can be compressed into column 1 (one) in Table 4.10(b). Columns 9 and 10 differ merely in the... 

Solution For each piece of equipment related to the safety instrumented function, one must ask if that equipment is needed to protect against the specified hazard. In this SIF, the hand-switch was added only to meet local regulatory requirements and is not part of the automatic protection so it is excluded. The pump is turned off to protect it from overload so it is not part of this SIF. The inlet valve for the other unit does not have to close to protect against this hazard so it is excluded. Although the need for the inlet valve closure is debatable, it does help reduce downstream pressure and was therefore included in the SIF. The SIF primary equipment is the LT-2025 level sensor, the VI-2002 Inlet Valve and the VI-2003 Outlet Valve. This is marked in the cause and effect diagram with an X. Other equipment is auxiliary. It is marked in the cause and effect diagram with an A. This information must be documented in the Safety Requirements Specification (SRS). 

Equipment that operates under pressure is specially designed to withstand that pressure and is fitted with a safety or pressure release valve or bursting disc to prevent excessive pressure developing inside it. The safe working pressure (S.W.P.) should be clearly marked on the equipment and it is important that this pressure is not exceeded. The gauge pressure must be observed regularly. 

Safety/relief valve quencher load test evaluation for BWR Mark II and III containments, US Nuclear Regulatory Commission, 1982. 

Gases must be clearly identified with legible labels and markings. Do not trust or use color coding for identifying the contents of a gas cylinder. Gas cylinders should be stored in a dry and well-ventilated area. These areas should also be away from mechanical or physically active areas, electrical circuits and panels, and sources of heat. Often these areas are outdoors but covered to keep them out of rain and direct sunlight - heat increases pressure and too much pressure could release gas through safety relief valves. 

All manual valves and valve operators shall be located in areas readily accessible to operating personnel. If valves are installed in areas of high radiation or other hazards they should be provided with extended stems or equivalent devices allowing actuation from a lower radiation area. Handwheels and chain or extension handle operators should be located at a reasonable height above either the floor or a permanently installed platform to allow easy operation. Piping ducts and valves should be located and marked such that the operators can easily identify the flow paths. Pipes or ducts that cross the normal and safety pathways should be at least 2 m above the floor. 

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