Pipework

Unlike reactor vessels where both hot- and cold-shell designs are extant, all CRU transfer pipework operates in hot service in a temperature range of approximately 400-530 °C. Parent material is generally of l-lV4CrV2Mo 

15 Quantification of creep damage variation through reactor wal (outer surface = 1 mm, inner surface = 100 mm). 

16 Removing damaged weld metal and HAZ from inlet nozzle weldment. 

17 Nozzle weld profile after damage removal. 

78 Examples of reheat cracking (left-hand) and Type IV cracking (right-hand) in butt welds. 

---

Material transfer requires pipework, valves, pumps, and compressors. Fugitive emissions occur from pipe flanges, valve glands, and pump and compressor seals. 

Filtration of viscose is not a straightforward chemical engineering process. The solution of cellulose xanthate contains some easy-to-deal-with undissolved pulp fibers, but also some gel-like material which is retarded rather than removed by the filters. The viscose is unstable and tends to form more gel as it ages. Its flow characteristics make the material close to the walls of any vessel or pipe move more slowly, get older, and gel more than the mainstream viscose. So while filtration can hold back gels arising from incomplete mixing, new gels can form in the pipework after the filters. 

Many initiators attack steels of the AISI 4300 series and the barrels of the intensifiers, which are usually of compound constmction to resist fatigue, have an inner liner of AISI 410 or austenitic stainless steel. The associated small bore pipework and fittings used to transfer the initiator to the sparger are usually made of cold worked austenitic stainless steel. The required pumping capacity varies considerably from one process to another, but an initiator flow rate 0.5 L / min is more than sufficient to supply a single injection point in a reactor nominally rated for 40 t/d of polyethylene. 

Tolerance Whenever possible, equipment should tolerate poor installation or operation without failure. Expansion loops in pipework are more tolerant of poor installation than bellows are. Fixed pipes, or articulated arms, if rlexibihty is necessary, are fiiendher than noses. For most apphcations, metal is friendlier than glass or plastic. 

Cryogenic -273 to -20°C Copper alloys Austenitic (stainless) steels Aluminium alloys Superconduction Rocket casings, pipework, etc. Liquid O2 or N2 equipment... 

The protection station must be carefully maintained (see Section 10.5). The function of the rectifier should be monitored at monthly intervals. The pipe/soil potentials of the pipelines should be measured at least once a year. The IR-free potentials should be determined as far as possible by the switching method, especially when new pipework is installed and connected to the protection system. 

The electrolysis protection process using impressed current aluminum anodes allows uncoated and hot-dipped galvanized ferrous materials in domestic installations to be protected from corrosion. If impressed current aluminum anodes are installed in water tanks, the pipework is protected by the formation of a film without affecting the potability of the water. With domestic galvanized steel pipes, a marked retardation of the cathodic partial reaction occurs [15]. Electrolytic treatment alters the electrolytic characteristics of the water, as well as internal cathodic protection of the tank and its inserts (e.g., heating elements). The pipe protection relies on colloidal chemical processes and is applied only to new installations and not to old ones already attacked by corrosion. 

Information on the costs of cathodic and anodic internal protection of tanks varies very widely since the costs depend not only on the material costs but also on the special installation costs and these in turn depend on the internal geometric layout of the tank and its pipework. 

PRESSURE SYSTEM Defined in the Pressure System Safety Regulations 2000 as a system containing one or more pressure vessels of rigid construction, any associated pipework and protective devices the pipework with its protective devices to which a transportable gas container is, or is intended to be, connected or a pipeline and its protective devices which contains or is liable to contain a relevant fluid, but does not include a transportable gas container. Here relevant fluid is steam any fluid or mixture of fluids which is at a pressure of >0.5 bar above atmospheric pressure, and which fluid or a mixture of fluids is a gas, or a liquid which would have a vapour pressure of >0.5 bar above atmospheric pressure when in equilibrium with its vapour at either tlie actual temperature of the liquid or 17.5°C or a gas dissolved under pressure in a solvent contained in a porous substance at ambient temperamre and which could be released from the solvent with the application of heat. 

Pressure rupture of even a small pieee of equipment may result in a serious explosion generating missiles travelling at high veloeity. This is an important eonsideration when using laboratory glassware or industrial glass equipment and pipework. 

Liquids can also exert pressure due to thermal expansion. Table 4.15 provides an indication of pressure increases due to temperature increases for selected common liquids in full containers or pipes. Serious accidents can arise unless the design of rigid plant items such as pipework takes into account the changes in volume of liquids with temperature fluctuation by the following or combinations thereof ... 

Ensure that pipework and eontrol systems are adequate to eope with the pressures assoeiated with storage and eonveyanee of earbon dioxide, whieh are higher than those eneountered with most other eryogenie liquids. 

High pressure work in heavy black iron pipework. High pressure Monel or aluminium iron bronze valves... 

Ensure that equipment, e.g. pipework for oxygen serviee, is kept elean and free from oil, grease or dust. 

Table 12.10 Design measures to reduce leaks from pipework...

Provide flexibility to allow for thermal expansion, or contraction, of pipework and connected equipment. 

Provide walkways, ladders, etc. to avoid pipework being clambered over. 

Have a suitable written scheme drawn up or certified by a competent person for the examination at appropriate intervals of most pressure vessels and all safety devices, and any pipework which is potentially dangerous. Advice may be sought from any competent person when deciding what vessels and parts of the pipework need to be included. 

At the completion of the transfer of dangerous liquids the berth operator should render pipework, valves and associated equipment safe valves and tanks should be closed and shore pipeline blanked off. 

Cover means of communicating health and safety information m all workplaces. Include illuminated signs, alarms, verbal communication, fire safety signs, marking of pipework, etc. 

Minimum number of mass exchanger units. Combinatorics determines the minimum number of mass exchanger units required in the network. This objective attempts to minimize indirectly the fixed cost of the network, since the cost of each mass exchanger is usually a concave function of the unit size. FuithetTnore, in a practical context it is desirable to minimize the number of separators so as to reduce pipework, foundations, maintenance, and instrumentation. Normally, the minimum number of units is related to the total number of streams by the following expression (El-Halwagi and Manousiouthakis, 1989). 

A basic distinction is made between confined unconfined explosions. Confined ex occur within some sort of containment such as a vessel pipework, or a building. Explosio open air are unconfined explosions. 

---