Equipment and Piping Isolation

It is common practice in the chemical process industries to provide isolation devices for stopping flame fronts, deflagration pressures, pressure piling, and flame-jet ignition between process equipment interconnected by pipes or ducts. There are several devices for providing this isolation as follows  

This type of isolation device (also called a chemical barrier) is similar to deflagration suppression systems used on process equipment. This barrier system consists of an optical sensor, installed in the pipeline or duct between two items of equipment, that detects an oncoming deflagration 

Snppressant harrier systems have the same shortcomings as cited in Section 3.6. In addition, the location of the sensor is critical to the snccessfnl isolation of a deflagration flame in a piping system. Bartknecht (1981) states that the flame sensor is installed at a distance of 1 meter from the ignition sonrce, and the extingnisher nozzles at a distance of 10 meters from the ignition sonrce. 

Fignre 3-13 is a schematic of a deflagration snppressant harrier system for pipelines. 

Fnrther information on snppressant harriers can he fonnd in NFPA 69 (1997), and the hooks hy Bartknecht (1981 and 1989) and Eckhoff (1997). 

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It should be possible to easily isolate fluids in equipment and piping when potentially dangerous situations occur. This can be done using emergency block valves (EBVs). An EBV is a manually or remotely actuated protective device that should be used to provide manual or remote shutoff of uncontrolled gas or liquid flow releases. EBVs can be used to isolate a vessel or other equipment, or an entire unit operation. Manual valves are often used on piping at block limits where it is unlikely that there would be a hazard to personnel if an accident occurs. Remotely controlled EBVs are recommended on tanks and on piping in areas where it may be hazardous for personnel in the case of an accident, or where a quick response may be necessary. 

It should be possible to easily isolate fluids in equipment and piping when potentially dangerous situations occur. This can be done using emergency block valves (EBVs). An EBV is a manual or remotely-actuated protective device that should be used to provide manual or remote shut-off of... 

It should be possible to easily isolate fluids in equipment and piping when potentially... 

Uses. In architectural and industrial appHcations vibrational isolators are used to reduce transmission of vibration into building stmctures from rotating or reciprocating machinery, such as ventilating fans, pumps, chillers, industrial machinery, and the piping and ductwork coimected to this equipment (6). Vibration isolators also can be used to isolate vibration-sensitive equipment or noise-sensitive areas from sources of vibration. Examples are special pneumatic isolators to protect electron microscopes, and isolators used to support floating concrete floors in recording studios. 

The 1997 edition of the API RP 521 extends the two-thirds rule to include the upstream and downstream system. At a minimum, the inlet and outlet piping up to and including isolation valves must be designed for the two-thirds rule to be able to block in the exchanger. If the upstream and downstream equipment is not designed for the two-thirds rule, relief devices may be required on both the inlet and outlet piping to protect the piping and adjaeent equipment. 

Deflagration Isolation A method employing equipment and procedures that interrupts the propagation of a deflagration flame front past a point (usually in a pipe). 

It can be concluded that selection of proper material or lining for seawater application is important and depends on the criticality of the system, availability of standby system/equipment and availability of isolation devices for maintenance. For process piping in seawater application the success of proper lining or coating material depends on the suitability for in-situ/field application and the proper corrosion monitoring plan. 

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

Provisions for safe and rapid isolation of piping systems and equipment Use piping, gaskets, and valves that take advantage of modern technology Use strong vessels to withstand maximum pressure of process upsets Avoid inherently unsafe equipment Use pumps suitable for hazardous service... 

Safe and Rapid Isolation of Piping Systems and Equipment... 

Estabhshing a turnover procedure, which documents flow isolation and electrical lockout locations and protective equipment requirements, if the equipment or piping is to remain open for more than one shift. 

NFPA 30,5.9.4 29CFR1910.106(e)(6)(ii) 4.4.2.3 All equipment (such as tanks, machinery, and piping) where an ignitable mixture could be present shall be bonded or connected to a ground. The bond or ground or both shall be physically applied or shall be inherently present by the nature of the installation. Electrically isolated sections of metallic piping or equipment shall be bonded to the other portions of the system or shall be individually grounded. 

Leady oxide manufacture is potentially very hazardous. It is therefore vital to take adequate measures to minimise, or even eliminate altogether, possible lead dust emissions out to the working environment and thus exposure of the personnel which would cause health problems. This is achieved by the use of a closed (isolated) leady oxide production equipment and transport pipes from the storage silos to the paste mixing unit. Special attention should be paid to file manufacture of tubular battery plates. Until recently, tubular plates were filled with a dry mixture of leady oxide and red lead powders. 

Process technician—inspects area and ensures good housekeeping, blinds, isolates and clears equipment, vessels, tanks and piping, immobilizes power driven equipment (lockout/tagout), determines PPE required, fills out the permit, and posts it at the job site. 

Another form of redundancy is the excess capacity often built into plants with more than one processing line. If two sets of drying towers are used, for example, the capacity of each may be more than 50% of the plant design capacity. The primary justification for multiple trains usually is to enhance turndown capability or to allow continued operation even when one train must be shut down. The same approach may be taken with the cooling section. Given the sizes of chlorine gas headers, valves would be expensive and probably ineffective as shutoff devices. Many plants therefore use U- or J-shaped traps in the piping. These can be filled with water or acid to stop the gas flow and to isolate equipment for maintenance. 

There should be specific written procedures for routine maintenance of process equipment and instruments. There should also be specific written instructions for isolation (piping and electrical) and decontamination of process equipment before maintenance, with particular consideration to procedures for vessel entry. 

Will adequate design provisions exist for cleanup and preparation of equipment for maintenance of equipment/piping/control systems (including lockout of all energy sources and double isolation where required) ... 

The annex/auxiliary buildings nonradioactive HVAC system serves the nonradioactive personnel and equipment areas, electrical equipment rooms, clean corridors, the ancillary diesel generator room and demineralised water deoxygenating room in the annex building, and the main steam isolation valve eompartments, reactor trip switchgear rooms, and piping and electrical penetration areas in the auxiliary building. 

The containment air filtration system consists of two 100 percent capacity supply air handling units, a ducted supply and exhaust air system with containment isolation valves and piping, registers, exhaust fans, filtration units, automatic controls and accessories. The supply air handling units are located in the south air handling equipment room of the annex building. 

Particular attention was paid to fire safety for the primary and secondary sodium equipment and pipelines. Technical measures are provided to limit the scope of sodium leaks and fires. Thus all reactor-related auxiliary sodium system pipes leaving the reactor vessel are jacketed up to a second isolation valve (including the valve casings) and are located in partially leak-tight rooms. 

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