Pipes heat treatment

Extrusion Resins. Extmsion of VDC—VC copolymers is the main fabrication technique for filaments, films, rods, and tubing or pipe, and involves the same concerns for thermal degradation, streamlined flow, and noncatalytic materials of constmction as described for injection-molding resins (84,122). The plastic leaves the extmsion die in a completely amorphous condition and is maintained in this state by quenching in a water bath to about 10°C, thereby inhibiting recrystallization. In this state, the plastic is soft, weak, and pHable. If it is allowed to remain at room temperature, it hardens gradually and recrystallizes partially at a slow rate with a random crystal arrangement. Heat treatment can be used to recrystallize at controlled rates. 

All subsequent green coke operations were made in a second coker, which was fashioned from steel pipe approximately 18 cm in diameter and 25 cm in length. A metal plate was welded to one end and a metal collar was welded to the other end such that a steel lid could be bolted to the system. Typically, about 250 to 500 g of pitch were sealed imder nitrogen in the coker reactor and the system placed in a large temperature-programmable furnace. The heat treatment process was as follows. The temperature was raised 5°C/min to 350 °C and then l°C/min to 425°C and the temperature held at 425°C for 90 minutes. Finally the temperature was raised further at 3°C/min to between 500 and 600°C, and held there for 3 hours. The coker was cooled to room temperature and the material recovered to determine green coke yield. 

This type of cast iron is made by high-temperature heat treatment of white iron castings. The mechanical properties of malleable cast irons are given in Table 3.1 usually they are applied to the fabrication of conveyor chain links, pipe fittings and gears. 

In addition, a surprisingly large number of stress-corrosion cracking failures have resulted from the welding of small attachments to vessels and piping after stress-relief heat treatment has been carried out. 

B. Effluent line, pipe and heat-affected zone, isolated areas damaged no postweld heat treatment. 

K. Catalytic reformer combined feed piping welds and base metal postweld heat treatment. 

A-4 One required for each welding procedure, for each type of filler metal (i.e., AWS E-XXXX classification), and for each flux to be used. Test pieces shall be subjected to essentially the same heat treatment (including time at temperature or temperatures and cooling rate) as the erected piping will have received. 

If a weldment is allowed to cool prior to heat treatment, the rate of cooling shall be controlled, or other means shall be used to prevent detrimental effects in the piping. 

Post heat treatment, when required for pipe components after bending or forming, shall be performed in accordance with para. GR-3.6, including Table GR-3.6.1. 

Material used for reinforcement may differ from that of the run pipe, provided it is compatible with run and branch pipes with respect to weldability, heat treatment requirements, galvanic corrosion, thermal expansion, etc. 

Inspections by owner include inspections, verifications, and audits of the construction of piping systems, which include fabrication, welding, heat treatment, assembly, erection, examination, and testing, in addition to the construction organization s documented procedures, personnel qualifications, and quality control records. 

For use under this Code, the heat treatment requirements for pipe manufactured to A 671, A 672, and A 691 shall be as required by para. GR-3.6 for the particular material being used. 

When heat treatment is required, piping welds shall be made before the component is heat treated. 

For any activated carbon system, the capital costs will be dependent on contaminant types and concentration as well as treatment goals. Capital costs will also increase in cold-weather climates, since systems may require buried piping, heating, and housing units. The major contributors to operations and maintenance (O M) costs are treatment/replacement of spent carbon, disposal of residuals, and monitoring effluent concentrations (D11022L, p. 11-100). Also, activated carbon systems are usually part of a treatment train. Treatment costs will be highly dependent on the other systems used to deliver the contaminants to the activated carbon unit. 

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