Rolled threads

The rotor studs (Figure 5-20) shall be ground of the same material as the disk and have rolled threads. The studs shall have provisions for positive loeking to prevent unserewing of the studs during operation. 

Figure 12-7. Piston rods. Precision-manufactured rolled threads and induction hardening provide high fatigue strength and long life in heavy duty service. Standard rod material is AISI 4142 carbon steel other materials are available as required. Tungsten carbide coatings are also available for maximum surface hardness. Pistons are locked securely onto the rods. For higher pressure, smaller bore cylinders, the piston may be integral with the rod. (Used by permission Bui. 85084, 1992. Dresser-Rand Company.)...

Laps and seams (discontinuities due to dies during rolling) Processing Ferrous and nonferrous rolled threads Fluorescent liquid penetrant method Magnetic particle method with care for anomalous indications... 

Stage 2 Wrong manufacturing technique, e.g., rolled threads vs. machined threads... 

COC s can be issued for all materials. In the case of fasteners, COC s would state that the original rod met the referenced specification and the manufacturing process complied with the purchase order (e.g., rolled threads vs. machined). A COC contains no test reports (e.g., if a gasket was made from Teflon the COC should state it was made of Teflon and that it is being supplied). No tests were made to determine that it was Teflon it only states that the records indicate the supplier is confident that no substitutions have been made. 

Grade 7 bolts and screws are roll threaded after heat treatment. 

Rolled Threads Rolled threads are formed from a piece of round bar stock by die rolling or... 

Ground rods come in many sizes and lengths. The more popular sizes are %y%-> and 1 in. The y2-in. size is available in steel with stainless-clad, galvanized, or copper-clad rods. All-stainless-steel rods also are available. Ground rods can be purchased in unthreaded or threaded (sectional) lengths. The sectional sizes are typically %6,-in. or y2>-in- rolled threads. Couplers are made from the same materials as the rods. 

Rolled threads are often smoother because of the burnishing effect of the rolling operation. 

Rolled threads cannot be used for anchors having a minimum tensile strength of 150 ksi (1,030 MPa) or greater... 

Rolled threads on bolts and screws are preferred over machined threads due to improved strength and surface integrity. 

Tape may be made by a similar process. In this case the lubricant selected is a non-volatile oil. The preform is placed in the extruder and a rod extruded. The rod is then passed between a pair of calender rolls at about 60-80°C. The unsintered tape is often used for lapping wire and for making lapped tube. Sintering is carried out after fabrication. The current most important application of unsintered tape is in pipe-thread sealing. 

Calendering A process by which fabric or wire is passed through a pair of heavy rolls to reduce thickness, to flatten the intersections of the threads/wires and to control air permeability. Rolls are heated when calendering synthetic materials. Carbonized threads Nylon or polyester therads that have been treated to include varrying degrees of carbon. 

Place clean protectors on the field end of the pipe so that the thread will not be damaged while rolling the pipe onto the rack and pulling it into the derrick. 

When rolling down skids, roll pipe parallel to the stack. Do not let the pipe gather any momentum and strike the ends. This can damage threads even when the protectors are in place. 

Gold is the most ductile element. An amount of 1 g of gold can be stretched into a 24-km-long fine wire (actually, a thread). It can also be rolled (or beaten) into 100-nm-thick gold leaf. It then looks blue green in color, and red when light is shone through it. 

Transition joints are used to join dissimilar metals where flanged, screwed, or threaded connections are not practical. They are used when fusion welding of two dissimilar metals forms interfaces that are deficient in mechanical strength and the ability to keep the system leak-tight. Transition joints consist of a bimetallic composite, a stainless steel, and a particular kind of aluminum bonded together by some proprietary process. Some of the types in use throughout the cryogenic industry are friction- or inertia-welded bond, roll-bonded joint, explosion-bonded joint, and braze-bonded joint. 

A further problem of the size press operation is that of films splitting. At the exit of the nip, the film sometimes splits into two layers with one part following the paper and the other remaining on the roll surface. The problem manifests itself as small scale nonuniformities on the paper surface caused by threads of the size solution being drawn out and deposited unevenly on the surface to give a kind of orange peel effect. 

Fig. 7.11 Wake configurations for drops in water (highly purified systems), reproduced from Winnikow and Chao (W8) with permission, (a) nonoscillating nitrobenzene drop = 0.280 cm, Re = 515 steady thread-like laminar wake (b) nonoscillating m-nitrotoluene drop 4 = 0.380 cm. Re = 688 steady thread accompanied by attached toroidal vortex wake (c) oscillating nitrobenzene drop 4 = 0.380 cm. Re = 686 central thread plus axisymmetric outer vortex sheet rolled inward to give inverted bottle shape of wake (d) oscillating nitrobenzene drop = 0.454 cm. Re = 775 vortex sheet in c has broken down to form vortex rings (e) oscillating nitrobenzene drop d = 0.490 cm. Re = 804 vortex rings in d now shed asymmetrically and the drop exhibits a rocking motion.

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