Pipes brazing

Heat pipe tubes The absorbed heat is transferred by using the heat pipe principle without direct contact to the heat transfer fluid of the solar loop. In this case, there are two different ways of connection (1) the dry connection, where the heat has to be transferred from the condenser through the material of the header tube. This way the installation and removal of the tubes is much easier than with direct flow pipes brazed to the header. On the other hand, heat-conductive paste often has to be used, thus requiring that the pipes be installed professionally and (2) the wet connection, where the fluid of the solar loop directly flows around the condenser of the heat pipes. In this case, no heat-conductive paste is needed, but the exchange of tubes is more difficult. 

Ak ammonia piping should be standard (Schedule 40) or extra heavy (Schedule 80) steel having welded or screwed joints, respectively. Galvanized piping or brazed joints should never be used. Ammonia accepted for pipeline transportation must meet the fokowing specifications NH, 99.5 vol % min dissolved inerts, 0.16% max, ok, 5 ppm max and water, in the form of steam condensate, 0.2% min, or distiked water, 0.5% max. 

Branch Welds These welds eliminate the purchase of tees and require no more weld metal than tees (Fig. 10-127). If the branch approaches the size of the run, careful end preparation of the branch pipe is required and the run pipe is weakened by the branch weld. See subsection Pressure Design of Metallic Components Wall Thickness for rules for reinforcement. Reinforcing pads and fittings are commercially available. Use of the fittings facilitates visual inspection of the branch weld. See subsection Welding, Brazing, or Soldering for rules for welded joints. 

Flexible Metal Hose Deeply corrugated thin brass, bronze, Monel, aluminum, and steel tubes are covered with flexible braided-wire jackets to form flexible metal hose. Both tube and braid are brazed or welded to pipe-thread, union, or flanged ends. Failures are often the result of corrosion of the braided-wire jacket or of a poor... 

Provide permanent brazed or welded pipelines from the cylinders to near the points of gas use. Select pipe materials suitable for the gas and its application. Any flexible piping used should be protected against physical damage. Never use rubber or plastic connections from cylinders containing toxic gases. 

Flanged Bolted flange connectors. Figure 40.35, are suitable for most pressures now in use. The flanges are attached to the piping by welding, brazing, tapered threads... 

Brazed Silver-brazed connectors are commonly used for joining non-ferrous piping in the pressure and temperature range where their use is practical. Use of this type of connector is limited to installations in which the piping temperature will not exceed 425°F and the pressure in cold lines will not exceed 3000 psi. Heating the joint with an oxyacetylene torch melts the alloy. This causes the alloy insert to melt and fill the few thousandths of an inch annular space between the pipe and fitting. 

Brazements included in a piping system that is subjected to a temperature 1,000°F (538°C) and greater shall require tests in addition to those of ASME BPV Code Section IX. These tests shall be considered a part of the qualification procedure for such design temperatures. Two tension tests on production type joints are required, one at the design temperature and one at 1.05T (where T is the design temperature in degrees Fahrenheit). Neither of these production-type joints shall fail in the braze metal. 

All couplings (fittings) for newly constructed and repair brazements shall be manufactured with internal stops. The stops shall control the internal gap between the pipe component ends. For requirements of brazed joint pressure fittings, see ASME B16.50. 

The testing methods shall apply to the construction of pipe components and qualification of welding and brazing procedures in accordance with the requirements of ASME BPV Code Section IX, Parts IP and PL, and the engineering design as follows ... 

Hardness testing shall be conducted for welding and brazing procedure qualification tests, hot and cold bent formed piping, pipe components, production weldments, and brazements. 

When required by design, material specifications, and qualifications for welding and brazing, one or more of the tests maybe required, in addition to the test required for the construction of the piping system. 

The extmders were monitored using a pair of custom-made transmission probes inserted into the extruder die just downstream from the screws. Each probe consisted of a sapphire window brazed into a metal body a quartz rod behind the window piped the light to the end of the probe low-OH silica fiber-optic bundles connected the probe to the NIR analyzer, an LT Quantum 12001. Optical path lengths were typically between 0.3 and 2.0 cm. 

A brazing burner (Fig. 9) is used to obtain a flame with a higher temperature. It differs from a conventional burner in that its bottom part has two tubes with cocks. Air is fed into the burner via tube 7, and gas via tube 2. Air is supplied into the burner by a motor-driven blower, or it is fed in via a special air pipe from a central compressor plant. By regulating the supply of air and gas, you can obtain a flame of a various height and temperature. 

Brazing is widely used in assembling heat exchangers, piping systems, electrical products, cutting tools, bicycles, and control instruments, among many other applications. 

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