Relief plugging

If there is a hole in the ean, process liquid can get into the stator compartment. A pressure relief plug is therefore fitted to the compartment and should be used before the compartment is opened for work on the stator. Warning plates, reminding us to do this, are often fitted to the pumps. 

In canned pumps the rotor (the moving part of the electric motor) is immersed in the process liquid the stator (the fixed part of the electric motor) is separated from the rotor by a stainless steel can. If there is a hole in the can, process liquid can get into the stator compartment. A pressure relief plug is therefore fitted to the compartment and should be used before the compartment is opened for work on the stator. One day, an operator opened the pump without using the pressure relief plug. There was a hole in the can which had caused a pressure build-up in the stator compartment. When the cover was unbolted, it was blown off and hit a scaffold 6 feet above. On the way up it hit a man on the knee and the escaping vapor caused eye irritation. The worker was not familiar with canned pumps and did not realize that the pressure relief plug should be used before opening the compartment. 

Fixed power cords are common to machinery and household appliances, but care must be taken to ensure that the cord, strain relief, plug, and terminal block are type-approved and that the proper termination methods and makings are utilized. lEC-type terminal blocks (touch safe) are the preferred method for termination of the incoming power wiring. Other methods of termination are possible, such as for connection directly to circuit breakers, mains disconnect switch, PCBs and tabs/ screws on filters. Refer to the product standard for the alternative methods of input terminations. Solder connections shall not be the only method of fixing and in some cases are not allowed for high current connections. 

The lubrication system consists of a grease inlet on the motor bracket with capped grease fitting. The grease relief plug is 180° from the inlet to provide complete... 

In styrene service, vapor may condense in flame arresters, and the liquid formed is low in inhibitor. Liquid may polymerize and plug off the arrester. Possible solutions include cleaning the arrester frequently or using a PVRV (pressure-vacuum relief valve). 

Defective pressure gauge. 10. Plugged oil sump strainer. 11. Defective oil relief valve. PACKING OVERHEATING 1. Lubrication failure. 2. Improper lube oil and/or insufficient lube rate. 3. Insufficient cooling. 

External relief valves should be of the full-flow, non-chattering (modulating) style. In oil systems with relatively low pressure levels, the hydraulic-type relief valve becomes attractive because the plug lift is smooth, and instability during lifting is eliminated. The valves should be located as close to the pump as possible to provide fast reaction time. 

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. 

Pressure Relief Valve for Polymer Plugging Service... 

All pressure vessels should be equipped with one or more pressure safety valves (PSVs) to prevent overpressure. This is a requirement of both the ASME Code and API RP 14C (refer to Chapter 14). The PSV should be located upstream of the mist extractor. If the PSV is located downstream of the mist extractor, an overpressure situation could occur when the mist extractor becomes plugged isolating the PSV from the high pressure, or the mist extractor could be damaged when the relief... 

Balanced bellows type valves are normally used where the relief valves are piped to a closed flare system and the back-pressure exceeds 10% of the set pressure, where conventional valves can t be used because back-pressure is too high. They are also used in flow lines, multiphase lines, or for ptu affinic or asphaltic crude, where pilot-operated valves can t be used due to possible plugging of the pilot line. An advantage of this type of relief valve is, for corrosive or dirty service, the bellows protects the spring from process fluid. A disadvantage is that the bellows can fatigue, which will allow process fluid to escape through the bonnet. For HjS service, the bonnet vent must be piped to a safe area. 

Another example a solvent was put into a small reactor to remove some polymer, which was stuck to the walls. Some monomer, which was trapped behind the polymer, reacted with the solvent, and the pressure rose. Bits of polymer plugged the relief valve, and the pressure broke a glass connecting line [8]. 

The alternate concept which has been in use for many years is to fabricate or purchase a Tee connection upon w hich the two safety relief valves can be mounted on top of their full-port plug or gate valve with required locking lugs. 

A simple manifold is illustrated in Figure 40.41. This manifold contains one pressure inlet port and several pressure outlet ports that can be blocked off with threaded plugs. This type of manifold can be adapted to systems containing various numbers of subsystems. A thermal relief valve may be incorporated in this manifold. In this case, the port labeled T is connected to the return line to provide a passage for the relieved fluid to flow to the reservoir. 

More formal inspections also verily the operation of safety and other controls such as low water and fuel cutoffs, level controls, fusible plugs, pressure gauges, water glasses, gage cocks, stop valves, safety/relief valves, and BD valves and lines. Also, FW pumps, flue and damper arrangements, combustion safeguards, name plate specifications, set pressures, boiler connections, floats, mercury switches, bellows, and other components may be inspected. 

Flame arrestors required on vent lines 5. Relief valves protected from plugging ... 

I found today that stiff wires from the battery will break off the card supply plug pins as shown - use better connector or drill the card tie in place. Have been letting it flap in the wind, pins are too tender to do much of that need the solder joints expoxied for strain relief. Is idiot resistant in case you get the plug in backwards -fried a chip at 3 a.m. once. 

Fusible plug A safety relief device that will melt at a predetermined temperature. 

As a purge medium, to prevent pressure taps and other instrument connections and relief valves, from plugging... 

Often, relief valves do not open because their piping connection to the vessel is plugged with corrosion products, salts, or coke. Even if this connection is only partially plugged, the effective capacity of the relief valve is greatly diminished. 

A rupture disk is a thin sheet of metal installed below the valve, intended to protect the relief valve from plugging. The rupture disk ruptures at the relief-valve-set pressure. A better approach to retard this plugging problem is to maintain a steam purge, or inert-gas bleed, below the relief valve to prevent the accumulation of solids below the valve. 

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