Valves specification

Valve Application Technology Functional requirements and the properties of the controlled fluid determine which valve and actuator types are best for a specific apphcation. If demands are modest and no unique valve features are required, the valve-design style selection may be determined solely by cost. If so, general-purpose globe or angle valves provide exceptional value, especially in sizes less than 3-inch NFS and hence are very popular. Beyond type selection, there are many other valve specifications that must be determined properly in order to ultimately yield-improved process control. 

Pressure Rehef Valve Specification - Standard calculation procedures are applied to determine the size of the pressure rehef valve required for the maximum reheving rate, together with other information necessary to specify the valve. 

Table 4 provides an example of a typical Pressure Relief Valve specification sheet. The following notes indicate the basis for the times which are required in the Design Specification. 

Figure 7-33. Safety relief valve specification for process overpressure example.

Many of these lockout devices are not specifically designed for use in the chemical industry (e.g., chains, padlocks) and are available from a local hardware store or manufacturer specializing in safety equipment. Other lockout devices (for example, valve-specific lockouts or valve box-locks) are more specialized and must be purchased from safety or valve-related equipment vendors. 

A major difference between valve-specific lockout devices and the padlocked chain or cable lockouts discussed earlier is that valve-specific lockouts do not need to be secured to an anchoring device in the floor or the piping system. In addition, valve-specific lockouts eliminate potential tripping or access hazards that maybe caused by chains or cable lockouts applied to valves located near walkways or frequently maintained equipment. 

Individual safety relief valve specifications shall be communicated on API 526 specification sheets or equivalent substitute provided by the end user. When the relieving contingency is vapour and liquid, rates and properties for each at the allowable overpressure shall be provided. 

SPRING-LOADED PRESSURE RELIEF VALVE SPECIFICATION SHEET... 

Replacement of gate valves with ball valves (within the plant valve specifications or within regular usage for that service). (Depending on the level of maturity of your organization, and your written program, this valve substitution and the two examples that follow could require an MOC for this type of situation.)... 

All cylinders come equipped with a valve specific to the gas in the cylinder, and a cylinder cap. The cylinder cap prevents damage to the cylinder valve while it is in transport, or when it is not in service. If a cylinder were to be tipped over and dropped, damage to the valve at worst could create a dangerous projectile, and a serious fire and explosion hazard. All cylinders in service should be secured by straps or chains, and set on a untippable base, or holding cage, or gas cabinet so that they can not fall or be knocked over. 

The model allows to express dependencies not only between document types but also between versions of documents. As it is shown in Fig. 2.8, the aforementioned dependencies between documents of types LineList, Instru-mentSpecification, and SafetyValveSpecification (cf. Subsect. 2.3.2) can now be represented explicitly through the isBasedOn relation F First, the Instrument Specification vl.O is created, based on which the Line List vl.O can be established. Next, the Safety Valve Specification vl.O can be prepared, which in turn is the basis for the generation of the Instrument Specification v2.0. 

The following items should be included in any valve specification ... 

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