Blind Valve

The line-blind valve is used where an absolute positive line shut-off is required upstream and 

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Multielevation piperacks are usually needed to handle all the required services for piping, electrical, utilities, and instmmentation. The two-level rack is one of the most common but three-level ones are also used. The utility lines are usually mn in the upper level and the process lines in the lower levels. The larger-diameter lines are located to the outside of the rack to be closest to the column supports. Access platforms are required at the battery limit to provide operators access to the block valves and blinds. If long mns of hot pipe are required, a portion of the pipe rack needs to be dedicated to an expansion loop. A horizontal space in the piperack is provided for a set of lines to be flat-turned into a set of expansion loops with the large pipes located on the outside. AH of the pipe turns are in the same horizontal plane, which is an exception to normal piping practice. A flat turn takes up and blocks space for other pipes. Flat turns are generally only made from the outside of the rack to minimize this blockage. 

P IDs (piping and instrumentation diagrams) should identify instruments, sample locations, the presence of sample valves, nozzle blinding, and control points. Of particular importance are the bypasses and alternate feed locations. The isolation valves in these hues may leak and can distort the interpretation of the measurements. 

Sampling locations for the unit test should be readily and safely accessible. The sample gatherer should be able to easily access the sample point. An isolation valve should be installed at the location. If a blind is installed, this should be modified in advance of the test. The sample locations shown on the P IDs must be compared against the actual locations on the equipment. Experienced operators may provide insight into the suitability of the location in question. 

Transfer path is Verify open and clear transfer path before initi-blocked due to ating transfer closed valve, blind, Utilize pressure and flow sensors etc. Pressure is built up in system and leaks in piping occur. CCPS G-29... 

The smaller framed hot gas expanders are often equipped with two control valves, each controlling a segment of 30% and 20%, respectively, of the total inlet. It is possible to vary the inlet cross-sectional area of these segments, within limits, by later replacing individual nozzles with blind fillers or vice-versa. Other machines may feature full arc admission without control valves. 

Unit checkout Check that required mechanical work has been completed, tags and blinds pulled, and temporary piping disconnected. Plant supervision must certify completion of work. Cancel all entry and work permits. Utility system has been commissioned. Check blind list and inspect lines close bleed, drain and sample valves. 

A further hazard exists when eompressed air jets are used to elean maehine eomponents in workplaees flying partieles have eaused injury and blindness. Cylinders may fail if over-pressurized or weakened by the applieation of heat. Liquefied gases, e.g. butane or propane, respond more rapidly to heat than the permanent gases sueh as nitrogen or oxygen. Cylinders are normally proteeted by pressure relief valves, fusible plugs or bursting dises. 

Routing of Flare Header through Process Areas - Flare headers in process areas should be routed to avoid locations of particularly high fire risk, such as over pumps, near furnaces, etc. The headers and subheaders should also be laid out and provided with isolating CSO valves and spectacle blinds, unless prohibited by local codes, such that it is not necessary for flare lines to remain in service in units which are shut down separately. Blowdown and water disengaging drums should be spaced from process areas. 

The recommendations described in this Chapter go further than some companies consider necessary. For example, companies may put Do Not Operate notices on valves instead of locks, or to save time, they may turn a blind eye to occasional shortcuts. Nevertheless, bitter experience has convinced me that the reconamendations are necessary. 

Reflux drum Mixer or stirrer Breathing apparatus (BA) Slip-plate Refrigeration plant Knock-on (or domino effects) Nonreturn valve Blinded... 

AS—Air Supply BD—Blowdown BF—Blind Flange CBD—Continuous Blowdown CD—Closed Drain CH-O—Chain Operated CSO—Car Seal Open CSC—Car Seal Closed DC—Drain Connection EBD—Emerg. Blowdown Valve ESD—Emerg. Shutdown FC—Fail Closed FO—Fail Open HC—Hose Connection IBD—Intermittent Blowdown LO—Lock Open ML—Manual Loading NC—Normally Closed NO—Normally Open OD—Open Drain... 

Process flowsheets do not normally show companion flanges for valves unless these serve as blinds or for orifice plates. This detail is sometimes shown on the piping flow-... 

Colors in a laboratory should be coordinated, just as in a home. If pre-finished work benches are to be installed, they might set the color scheme. While they are available in several colors or combination of colors, the choice is not unlimited. In one case, the laboratory operator was color blind, so his wife took over the job as decorator. First, she selected a two-color scheme for the work benches. Color chips in hand, she then chose a floor covering from a number of samples submitted. For the wall paint, she found a standard color of the recommended quality that harmonized with the cabinets. A few appropriate charts and a colorful cloth wall-hanging of pipes and valves completed the decor. The result received many favorable comments from visitors to the facility. 

To achieve the more detailed improvements suggested above, it may be necessary to add a few questions to those asked during a normal HAZOP. For example, what types of valve, gasket, blind, etc. will be used ... 

Equipment that will not be tested shall be either disconnected from the piping or isolated by blinds or other means during the test. A valve may be used, provided the valve (including its closure mechanism) is suitable for the test pressure. 

Errors that resulted in the component being unavailable when needed—For example, equipment not restored to full operability following maintenance, testing, or inspection. Valves left closed, actuation or protective systems not reconnected, slip-blinds left in the line, or failing to return pump selector switches to the standby auto-start position are common examples. 

Consider adding a vapor line valve in place of a blind... 

Add A flanged drain connection with valve and blind at least 2" in size shall be included... 

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