Lining Failure

During some mol ding and extmsion operations, knit line failures, incomplete mold fill, die drag, and excessive heat buildup, ie, scorch, are problems. Many of these problems are reduced or eliminated by the addition of internal lubricants such as low mol wt polyethylene or Vanfre AP-2 Special, a product of R. T. Vanderbilt. 

Line failure due to vibration induced metal fatigue released hot oil under high pressure which ignited and spread to other portions the plant. 

Where a loading system s emergency shutdown system closes a valve on gravity or pipeline fed transfer systems, care should be taken to ensure the line is protected against pressure surges or hydraulic hammers which may cause gasket blowout or line failure (NFPA 30). 

One report stated thickness measurement a short distance away from the rupture showed the line was a nearly full design thickness. Investigators concluded the line failure was the result of the thinning of the Schedule 120 carbon steel 90-degree elbow due to long-term erosion/corrosion. [21] Another story stated the piping was originally or nominally 0.625 inches thick, but had worn down to 0.085 inches. [27] That represents an 86-percent wall loss. 

This velocity should never be exceeded for acid gas service because of the increased potential for a line failure due to erosion. 

May J, Murchan P, MacFie J, Sedman P, Donat R, Pahner D, Mitchell CJ. Prospective study of the aetiology of infusion phlebitis and line failure during peripheral parenteral nutrition. Br J Surg 1996 83(8) 1091. ... 

Even though the gases entering a stack may be above the acid dewpoint and safe from a corrosion point of view, if the stack is tall (>200 ft), the temperature may drop below the dewpoint once it reaches the top. This presents a familiar problem to many lining materials. The wet condition at the top of the stack causes lining failure and forces frequent maintenance. With the borosilicate glass block from bottom to top, the stack designer need not try to determine the transition point and then specify different materials for each section of the stack. 

The relatively severe conditions in an acid sulfite digester dictate the use of a multiple layer acid brick lining. The lining must be carefully selected and specified since these units operate at elevated temperatures and pressures with very acidic chemicals. Improper selection, design, specification, or installation can result in an unacceptably short lining life, lining failure, or vessel failure. 

Although the inherent chemical resistance of the rubber chosen is quite suitable for the given duty conditions, many a times the bond or adhesion failure is the cause of lining failure. Therefore much care is taken while applying the lining especially at joints, seam, corners and flanges. 

Refractory lining failure Acid piping and cooler leakages Corrosion of demister pads/failure of candle demisters Heat exchanger tube leakages Loss of catalyst activity... 

A Radiological Consequences of Main Steam Line Failures Outside Containment of a PWR... 

The total failure duration also shows a decreasing trend. The failure duration during forced outage to enable removal of line failures (unrecoverable by multiple switching of the lines on and off), however, these can never can affected positively by remote-controlled systems. 

Vacuum apparatus should be assembled so as to avoid strain. Joints must be assembled so as to allow various sections of the apparatus to be moved if necessary without transmitting strain to the necks of the flasks. Heavy apparatus should be supported from below as well as by the neck. The assembler should avoid putting pressure on a vacuum line. Failure to keep the pressure below 1 atmosphere could lead to the stopcocks popping out at high velocity or to an explosion of the glass apparatus. Such increased pressure could result from warming of the contents of the trap due to failure to maintain low tempa-atures. 

A line drawn along the centre of the proximal radius should intersect the capitellum (the radiocapitellar line). Failure to do so suggests dislocation of the radial head. This rule is always valid on a true lateral image, in all stages of flexion (Storen 1959). 

Weld Lines. In unreinforced polymers, smooth fracture surfaces may be a sign of weld-line failure (Fig. 13a). This is a case of adhesive failure the melt fronts were imable to join together in such a way that cohesive failure and the corresponding deformation in the fracture surface or different fracture planes, shown in Figure 13b, could occur. 

Linings properly selected, installed in a properly designed and prepared shell, and maintained will provide long years of satisfactory service. Despite this there are occasionally reports of lining failures that can be traced to one or more of the following causes, all of which could have been prevented. 

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