Fillets

Polymer systems have been classified according to glass-transition temperature (T), melting poiat (T ), and polymer molecular weight (12) as elastomers, plastics, and fibers. Fillers play an important role as reinforcement for elastomers. They are used extensively ia all subclasses of plastics, ie, geaeral-purpose, specialty, and engineering plastics (qv). Fillets are not, however, a significant factor ia fibers (qv). 

Static friction decreases with an increase in load, and the static coefficient of friction is lower than the dynamic coefficient. The tendency to creep must be considered carefliUy in FEP products designed for service under continuous stresses. Creep can be minimized by suitable fillers. Fillets are also used to improve wear resistance and stiffness. Compositions such as 30% bronze-fiUed FEP, 20% graphite-filled FEP, and 10% glass-fiber-filled FEP offer high PV values ( 400(kPa-m)/s) and are suitable for beatings. 

Butt-welded joint, reducer, or weld-neck flange Double-welded slip-on flange Fillet welded joint or pocket-weld flange... 

Imperfection f When required examination is Girth and miter-joint hutt welds Longitudinal hutt welds Fillet, socket, seal, and reinforcement attachment welds Welded branch connections and fabricated laps... 

Head attachment. UW-13. Fig. UW-13.1 Fillet welds. UW-18. UW-36 Table UW-12 Knuckle radius. UG 32. UCS-79 Torispherical head. Pressures. 

Tooth fillet working depth Whole depth... 

A fillet is a stagnant deposit of solids commonly found at the outside periphery of the bottom where it joins the tank. However, it could occur anywhere in the tank where the flow pattern is stagnant. Filleting is permitted, but no progressive fillet buildup is allowed. The reason is that it costs less to allow some solids to settle into fillets than to provide additional mixer horsepower to eliminate fillets. 

In continuous flow operations, a slurry is continuously added and withdrawn from a single-stage mixer. Progressive buildup must not occur in fillets, and the discharge composition to the mixer must equal the inlet composition. Discharge from the tank occurs at a particular draw-off point, the only point in the tank that requires the mixture to have the same composition as the inlet. 

Fig. 6. Adhesive fillet on honeycomb core. Reproduced by permission of the Boeing Company.

Adhesives for sandwich bonding progressed similarly. Early low-flow adhesives were used with plastic foam cores and end-grain balsa to manufacture sandwich as.semblies. The development of less dense honeycomb cores necessitated a change in adhesive. Development of good bond strength to honeycomb core requires relatively high flow so that an adhesive fillet forms on the core walls (Fig. 6). 

Adhesive bonding is an integral part of virtually all composite structure. Early composite matrix resins could in some cases act as an adhesive, such as with self-filleting systems used for honeycomb sandwich fabrication. As composite systems became more optimized for minimum resin content and limited flow, supplementary adhesives became more common. Modern-day composite structure relies on adhesives almost as much as bonded metallic structure. 

Table 2 contains the honeycomb sandwich bonding property requirements for the same adhesive. Note that 0.005" thick adhesive has no sandwich bond requirements because it does not contain enough adhesive to form effective fillets and so is not used for sandwich bonding. 

Single full fillet lap joints without plug welds. 

For the attachment of heads convex to pressure to shells not over A-in. required thickness, only with use of fillet weld on inside of shell or For attachment of heads having pressure on either side to shells not over 24-in. inside diameter and not over 11-in. required thickness with fillet weld on outside of head flange only. 

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