Repairs, temporary

Chemical plants must also have a method to review temporaiy repairs, temporary connections, or deviations from standard operations (see Fig. 13.1). 

Sticky waxes are used as thermoplastic cements. The broken pieces of a plaster impression are reassembled and held in position with sticky wax. Broken denture bases may be held in proper alignment for repair. Orthodontic apphances may be assembled with a sticky wax prior to investing and soldering. Plaster splints may be sealed to stone models in the production of porcelain or resin facings. Thus, sticky wax is useflil in almost any operation where it is desired to position and hold several small pieces in a temporary relationship. 

Reduce Head on Liner and/or in Leachate Collection System Inspect Leachate Collection/Removal System or French Drain Repair Leachate Collection/Removal System or French Drain Temporary Cap... 

Temporary Pipe Section Fig. 7.1-6 Temporary Repair ai Flixborough... 

Unfortunately, the water contained nitrates, which caused stress corrosion cracking of the mild steel reactor. The reactor was removed for repair, and the temporary pipe that replaced it later failed and caused the explosion (see Section 2.4). 

The severity of consequences of damage to property (temporary, repairable, permanent). 

If a chain breaks or fails due to broken pins, sidebars, or rollers, temporary emergency repairs may be required to prevent a lengthy shutdown. Please note, however, the entire replacement of the chain is preferred for the following reasons ... 

Since continuity of the process and safety are prime considerations, plant security will require duplication of all items of apparatus so that a temporary shut-down for repair or maintenance will not reduce the cooling capacity. 

Identification of the Equipment Many accidents have occurred because maintenance workers opened up the wrong equipment. Equipment that is under repair should be numbered or labeled unambiguously. Temporary labels should be used if there are no permanent ones. Pointing out the correct equipment is not sufficient. The pump you repaired last week is leaking again is a recipe for an accident. 

Cytotoxicity is the general term used to describe toxicity at the level of the cell. It can be brought about in many ways, usually by a chemical interaction between the toxic agent and one or more components of the cell. Interactions can be permanently damaging or may lead to temporary injury that the cell is capable of repairing. Perhaps the most important sites of intracellular injury are cell membranes, the cell nucleus (home of DNA), mitochondria (home of energy production), and endoplasmic reticulum (home of the biosynthesis of the all-important protein molecules, essential for cell structure and, as enzymes, for the catalysis of all cellular reactions and for the metabolism of foreign chemicals). 

Poor housekeeping may also be a symptom of other fundamental problems, such as careless operation, frequent temporary repairs, and generally inadequate maintenance. These conditions can result in process leaks, releases, and spills, missing or open covers on equipment and electrical panels, unpainted rusting metal, and nonfunctional gauges and instruments. 

When a fire protection impairment is planned or occurs accidentally, precautionary measures are necessary to minimize the risk. These may include arranging temporary protection, reducing hazards, and ensuring continual and speedy progress on repair and restoration efforts. 

Although it is generally considered that response to a toxicant is determined by the availance J Cdt, it must clearly also be expected that there is some threshold of concentration below which the toxicant can be tolerated indefinitely the toxicant arrives so slowly that replacement and repair reactions can compensate for any damage. At the other extreme if the pulse is too rapid the temporary disruption of the vital process may be too short to produce irreversible effects. There is thus likely to be only a defined range of pulse forms producing the specified biological response for any applied dose and since pulse form depends so strongly on P. an optimum value for the partition coefficient within a series of related compounds. 

Figure 5.13 A control chart showing two consecutive days in which the measurement or analysis result was outside the action limit. An example of a cause is a distilled water line that was repaired, causing temporary contamination.

If a pinhole appears whilst the vacuum line is in use and cannot be opened, a temporary repair can be made with black wax (Apiezon or similar) as follows The wax is warmed and worked into a short rod about the diameter of a match-stick and about 1 cm long. The region of the pinhole is warmed with a very small flame, the black wax is applied to the pinhole as a spot not more than 2 mm in diameter, and then warmed with a very small flame just sufficiently to flow and wet the glass. Before a pinhole patched up in this way is repaired properly, all traces of the wax must be removed with a solvent, otherwise the charred remains and ash from the wax will spoil the glass and make a proper fusion repair that much more difficult. 

The second step is to agree on an approach. This is easy to say. The plan must cover defining roles and responsibilities. Also, there must be provisions for temporary repairs or installations, emergency changes, and variance policy. Also decide if it seems best to unite the Management of Change and the Pre-startup Safety Review in the same procedure. 

Once a system is (temporarily) repaired, there is a good chance that the need for a permanent repair will drop ( out of sight, out of mind ). Temporary repairs are, at best, temporary and should not be relied on for future needs. 

Glyptol, or other temporary leak repair material, can be very difficult to properly remove from a glass surface. Total removal of any temporary sealant must be done before any glassworking can be done. 

Obviously there will be times when the temporary repair of a leak is essential, but otherwise it is best to make all repairs permanent. 

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